# Growing large silver crystals



## peter i

Harold once posted some pictures of very large and beautiful silver crystals.

How were they grown? I'd love to grow some 

(I'm a chemist, I love crystals... can't help it, sorry!)


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## Harold_V

An elderly friend, now long departed, grew them in an enclosed container in which he had a pointed electrode on one end, with a small anode of silver attached to the other end. I never saw his setup----but we discussed it at length. Unfortunately, he died back in '84, so my memory has dimmed considerably. 

Silver will grow crystals if you keep the purity of electrolyte high and limit it's ability to plate out of solution. On rare occasions, a spot in my silver cell would grow a few that were large enough to save, although I don't recall that I saved any of them aside from maybe one. They were not large, perhaps fingernail size at best, but my objective was to purify silver, not to grow large crystals. 

Incidentally, when you operate a silver cell, it becomes obvious that the silver grows as crystals, albeit small ones. It appears to me that if you limit area, you'll get nothing but large crystals, but I don't know that. 

Do use pure silver, no copper. Copper, from my experience, tends to form soft crystals that won't grow large in size. The few relatively large crystals that I grew always came early in the operation, before the copper level of my electrolyte increased. I used silver crystal to make my electrolyte, adding no copper. As the level of copper increased, the nature of the crystal changed considerably, finally growing nothing but long strands of silver threads, very soft. Shortly thereafter, copper would start to co-deposit with the silver. On such occasions, I'd simply place the once refined silver back in the basket and part it a second time, using new electrolyte and an anode that was placed on top to insure good electrical contact. 

Hope some of this helps. 

Harold


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## peter i

Thanks
Even if it’s not a recipe, it certainly points in the right direction.

I’ve made a relatively primitive experiment, just a fine silver wire and a bar of (relatively) fine silver (chloride precipitation, then reduced with zinc) hanging in ½ a litre of silver nitrate solution (dissolving 30 grams of copper cemented silver in 30 mL of nitric acid + 30 mL of water, then diluted to 500 mL with distilled water).
(Some copper must have remained, the solution was light green)

Running at approx 4 amps, the silver precipitates as a relatively fine powder when the solution is cold, changing to long feathery crystals as it warms. I guess they are less than half a millimetre wide, and up to 15 mm long before dropping to the bottom.
High voltage seemed to encourage “strandy” growth.


Guess I’ll have to refine some more, do it carefully, and then try it clean, slow and at only a couple of volts.


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## peter i

Well, I'm going to try it one of these days. (Just have to get my power supply available from another experiment first)

A thin solution of silver nitrate (chemically pure), a bar of fine silver and an isolated silver wire, with just the tip exposed.
Sealed in a flask to avoid loosing water and introducing dirt.

Low temperature, approx 10°C
Low concentration, 0.25M, 0.5M as a reserve if nothing happens.
Low voltage, just 1½-2 Volts 
Loooong time, I guess


Apparatus as shown below.
(I know that this is "playing", but most of us are doing just that anyway)


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## Harold_V

My friend's container was flat, which is conducive to supporting large crystals. Electrodes were on opposing ends, near the bottom. The container was relatively shallow, and made of plastic as I recall. 

The one thing I remember is that the cathode was just a point---so the silver had no option but to form in an isolated place. You might give that some thought. Anode and cathode spacing, along with electrolyte concentration, will play a role in voltage. I agree, low amperage, but do experiment. I'm not convinced you want the concentration particularly low. I used 30 troy ounces of silver in my electrolyte for my parting cell, which held about 8 liters of solution. Hope some of this is helpful. It's been years since I last did any of this stuff. 

Harold


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## peter i

Harold_V said:


> My friend's container was flat, which is conducive to supporting large crystals. Electrodes were on opposing ends, near the bottom. The container was relatively shallow, and made of plastic as I recall.


Great, I'll try that too! (It makes sense, and it will be quite easy to do)




Harold_V said:


> The one thing I remember is that the cathode was just a point---so the silver had no option but to form in an isolated place. You might give that some thought.



So is mine. The L-shaped part is isolated, first by a thick layer (black), then by a thinner (dark green), only at the wery tip is the silver exposed by ½ a millimeter.



Harold_V said:


> I'm not convinced you want the concentration particularly low. I used 30 troy ounces of silver in my electrolyte for my parting cell, which held about 8 liters of solution.
> Harold



Wow, that's 114 grams silver pr. litre :shock: equalling 181 grams of silver nitrate.
The solubility of silver nitrate is 170 g/100 mL at 10 °C and 257 g/100 mL at 25°C. Practically a saturated solution.

My fault, by the way, I used the wrong argument for low concentration.
Crystals will form when a solution is super-saturated. The normal way to control that reaction when growing large crystals, is to just supersaturate it slightly, normally by using a weak solution or changing the temperature.
But here, the supersaturation is caused by current, not concentration.

Thanks, you really are a great help. (Help from people who have "been there, seen it, done it" is very valuable!)

Regards
Peter


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## Harold_V

peter i said:


> The L-shaped part is isolated, first by a thick layer (black), then by a thinner (dark green), only at the wery tip is the silver exposed by ½ a millimeter.


Very good! I couldn't tell that from the pic. You're on the right track, for sure. 



> Wow, that's 114 grams silver pr. litre :shock: equalling 181 grams of silver nitrate.
> The solubility of silver nitrate is 170 g/100 mL at 10 °C and 257 g/100 mL at 25°C. Practically a saturated solution.


Heh! I'd dissolve that 30 ounces in a 4,000 ml beaker, using a liter of nitric and adding enough distilled water to get it going, then apply heat, taking it to boiling. After it had boiled for a prolonged period of time the vast majority of the silver was gone, although if there were traces, they were simply included in the cell with the electrolyte. I used silver crystals from the cell to make new electrolyte, so it made no difference. 

Interestingly, as the solution cooled, unless I added more distilled water, it formed huge crystals of silver nitrate. Yep-it was damned well saturated!  



> Thanks, you really are a great help. (Help from people who have "been there, seen it, done it" is very valuable!)
> 
> Regards
> Peter


I wish I could have provided more guidance. Growing crystals was not my concern, although some grew of their own accord, as I suggested. Had I held greater interest, I'd have learned more from my old friend. Too late now, so I'm relying on you! Please give us all a report on your success, and don't hesitate to show us some pics. They're always welcome. 

By the way, my friend grew a few crystals that bordered on ten troy ounces. He really enjoyed good success. 

Harold


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## peter i

First try:

2 grams of analytical grade silver nitrate dissolved in 15 mL of distilled water.

The tray is a polystyrene "specimen box" (shown without the lid in the photo).

Fine silver wires are pushed through the ends and secured with hot melt glue.

Power supply was a large 1½ Volt Duracell.

It failed misserably. In just one hour, a long strand of crystals grew from one end to the other.
:evil: 


Next try will be from a dilute solution (diluting the present solution with a factor of 5, I guess)


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## lazersteve

Pete,

Looks like you had success to me! GSP once mentioned using motion to keep the crystals from shorting out your rig. Maybe if you just rock the dish every once in a while you can break the strand and form granules of pure silver.

If you want big bulky crystals you may try putting a resistor inline with the positive lead to limit the current so it doesn't make a B-Line to the negative lead. Another possibility would be to put a partition in the cell to stop the progress of the crystals across the cell. 

I think your 'mini-cell' is awesome!  

Steve


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## Anonymous

cut that crystal halfway leaving one end attached, then continue growing,
and cutting out the short, eventually the half your saving would be quite massive. 

I think that could work.


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## Harold_V

I'm of the opinion that your voltage is too high (for conditions). I ran my parting cell at approximately 3 volts, but the spacing, anode to cathode, was about 3". 

A resistor isn't a bad place to start, or achieving a greater space between the two poles might be helpful. It will be interesting to see if a lower concentration will work, too. The electrolyte will likely seek its own level once the cell operates to your satisfaction. Could be a lower concentration would be helpful---it certainly should change conductivity. 

What you accomplished is very pretty! You're on the right track. 

Harold


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## peter i

Thanks guys!

Test number two used a 1:4 dilution of the ”2g @ 15 mL” solution, but yielded the same result.
The crystals grew 20 mm in a little more than an hour. Even if it doesn’t work the way I intended, it’s a nice chemical demonstration. Placed in a Petri dish on an overhead projector, it could grow throughout a lecture (a modern projector with camera would give cool pictures).

You’ve given three suggestions:
-	Pruning, to just keep a single crystal growing
-	Rocking to break up the crystals
-	Changing the power supply

I’ll start with the power. This goes well with the observation, that high voltage gives a strandy growth. 
It’s easy to do, and easy to control (and will need less attention on my part). A variable resistor should do the trick.

But should it be hooked up as a rheostat, limiting the current, or as a potentiometer, limiting the voltage?
If Harold's guess is right, it's the pot-meter solution.
( http://www.kpsec.freeuk.com/components/vres.htm just a a reminder to myself. I'm a chemist, not an electronics guy :shock: )

I recently scrounged a lab power-supply. After restoring it (ie: washing out the chemical deposits inside it, yuck! Beating out the dents in the cabinet and replacing the proken connectors), I’m exited to see if it will work when I plug it in or if I’ll just turn out the light in the neighbourhood :? 
It may come in handy, once the pilot study is done.



This is my ”micro-cell” by the way. My “mini-cell” is a 500 mL cell made from a rectangular glass vase and some Perspex (an excuse for experimenting on the welding of Perspex with chloroform 
It just sits on the workshop table, growing larger crystal than the micro-cell!


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## Harold_V

The reason I suggested voltage control is that's how I managed to run my cell for a prolonged period of time without shorting. It ran 24/7 for weeks on end, until I'd processed all the silver I had at hand. I'd then accumulate again until I needed to refine, then start over. 

It's been years since I ran a cell, but I recall that the recommended amperage per sq. ft. was something like 15 amps. What ever voltage it took to achieve that amperage is what I used at first, having a Variac in my power supply (home built). I simply controlled the voltage fed to the transformer. The first day of operation kept me jumping--so I reduced the voltage, which had a corresponding decrease in the amperage. Seems I ran it at about 12 amps/ft, but I'm not sure. Could be I have the information saved, which I'll check when time allows. 

I screwed with the voltage until I found a place where it produced nicely, producing more coarse crystals than hair or wire, and then I ran it there. I never went back to the higher voltage, finding it was to my benefit to slow it down and produce coarser crystal. I'd have to get up during the night to knock it down (my lab was at home), but only once. I ran it that way constantly, which actually proved to be quite adequate. It allowed me to pursue my other duties, checking on the cell only about every 3 or 4 hours. As slow as it was, I'd still turn about 100 ounces in a day or a little longer. Not as bad as it may sound, at least for a small operation. 

Bottom line----I truly believe that lower voltage will help. Keep us posted! 

Harold


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## peter i

The lab-supply works like a charm! (unbelieveable regarding the punishment it had taken! White crystalline crusts and abominable brown gunk inside. Add to that a couple of good dents in the cabinet, circuitboards dangling loose and a nut that should have secured the cabinet gone AWOL. But she has a good home now 8) )


Experiment #3 is cooking  

15 mL micro-cell
The dilute silver nitrate from #2, 
0,48 Volts,
current limit set at ½ Ampere (just to keep it cool if it shorts out). 

regards
Peter


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## Anonymous

What about a pulsed voltage like from a cell phone charger.


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## peter i

peter i said:


> Experiment #3 is cooking
> 
> 15 mL micro-cell
> The dilute silver nitrate from #2,
> 0,48 Volts,
> current limit set at ½ Ampere (just to keep it cool if it shorts out).



No "discrete single crystal synthesis" yet, but a small dense cluster of larger crystals. The largest is coming close to 5mm. 

It looks promising, and will be allowed to run for another week.


I'm considering using a small single-crystal as a seed for the next run, to have a single well defined crystal lattice to start from.
Experiment #3 just went on in the same substrate as #1 and #2, and there were plenty of small crystals remaining (to act as multiple seeds).


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## austexjwlry

Peter i,

I had 8 filters full to the brim of clean gold from deplated items and some gold already recovered from inquarted jewelry items, approx. 20 grams to a filter dissolving in some AR outside in a coffee pot. After it quit fuming I put it and the plastic bowl it was in inside my storeroom to let it finish working while I did other chores.

My wife of 18 yrs whom I still love very much was putting a couple bags of aluminum cans into the same storeroom but didn't like the smell so she threw the bags of cans onto her pile from the open door! One of them fell into my bowl and coffee pot spilling the contents onto the pressboard floor!

She put on my gloves and started cleaning up the spill with paper towells. she is very mildly asthmatic anyway, so we ended up going to the E.R., 4 days later we were able to come home. Watching her suffer was the most traumatic ordeal I've ever been through!

I cleaned up what I could with paper towels using a spray bottle to squirt water onto floor and soaking up with paper towels until there was no hint of yellow on the paper towels.

I squeezed the about 3 gallons of water containing a little Ar and gold into a bucket. It was quite yellow in color. I tried to precipitate the gold from this mostly water solution using SMB but only a few grams came down. It was still quite yellow. I boiled it down to about a quart and about 20 grams of gold self precipitated. I filtered the gold out of this solution which has turned a yellowish brown color. The remaining solution was sitting in the pyrex pan for almost 4 days when I noticed the crystals had formed. I was waiting to add the AR from dissolving the gold in the paper towell ashes to boiled down solution.

I still have to cut up and burn the deep purple stained pressboard floor and refine the ashes. I just thought you might like to see the crystals!

Best Regards,

Wayne


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## peter i

Nice crystals! And sorry to hear about your wife!

I’ve always thought that “Keep out of reach of children” should be “Keep out of reach of children and spouse”.

Luckily my workshop is a dedicated workshop, so there is no other traffic in there. If something potentially nasty is going on, the door is locked.

My son made his first attempt of “making it go booom” at the age of three. He’s a “creative lad with lots of initiative”

Wonder what those crystals are?
I would separate them from the liquid, dissolve in a minimum of water and test for gold. If it is gold chloride, the resulting gold after a sulphite reduction would be very high quality (recrystallisation is a great way to clean things). If it is not gold, then it’s just nice to get rid of it.

Regards
Peter


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## Lou

Too bad gold chloride crystals are a deep red. Anhydrous AuCl3 will never just crystallize out of solution Peter. Far too good of a Lewis acid, and far too happy to gain a proton 8) 

Anhydrous AuCl3 is made from gold and chlorine, quartz tube and tube furnace. It is transiently stable in aqueous solutions, more so in alcohol and polar solvents if I remember correctly.


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## peter i

quite right... still wonder what it is!

(Asking for you to send a sample to Denmark to let me make a PXRD on it, is a little overkill)


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## Harold_V

Lou & Peter, 

Speaking as the novice I am, I have a question about your statements. Bare in mind, I do not understand chemical terms, so I'll talk in common language, and would appreciate an explanation that will make sense to someone of my level of understanding. 

I'll begin with the fact that I've dissolved a large amount of pure silver in my days. It was used as electrolyte for my silver parting cell, and was usually dissolved, diluted and immediately put to use. On rare occasion, however, that was not the case. I can recall on no less than a couple occasions, I had dissolved all of the 30 troy ounces of silver that I used for the cell, but not diluted the solution, which was roughly two liters in volume. I could rely on a liter of nitric to dissolve the bulk of the silver, but I had a policy of using 50% (distilled) water, which made a huge difference in the dissolution rate, plus, from what I've read, greater service from the nitric (some talk of the hydronium ion, which I do not fully understand). 

At any rate, when this highly concentrated solution was permitted to cool, it, almost immediately, started growing silver nitrate crystals. The entire lot became a solid mass, more or less. 

Armed with the above information, are you folks telling me that if a concentrated solution of gold chloride was permitted to cool to room temperature, that no crystals would form? Seems a bit strange, but then I do not understand chemistry as you two do. I'd certainly appreciate anything you might be able to tell me in that regard. I had long assumed that's all it would take to grow the crystals. 

Harold


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## Lou

What you had occur Harold was saturation of your solution--it couldn't hold any more silver nitrate at that temperature. You did this all while the solution was hot and is it cooled down, the situation got worse: the solubility of silver nitrate in your water decreased and left you with an unstable supersaturated solution, which crashed out your AgNO3. As an aside, by dilution of your concentrated nitric with distilled water, you increased the amount of hydronium ion (H3O+, what makes an acid an acid, at least inorganically). The reason for that lies in equilibrium--more solvent means the acid dissociates more completely. The greater service from the nitric is again due to equilibrium--more water means the NO2 produced can redissolve in water and make more nitric.

Now the difference with the AuCl3 lies in the fact that it is unstable in solution. Pure gold chloride forms red, monoclinic crystals. It is also hygroscopic (loves water), when this water gets into it, it forms a new compound, a hydrated one, with a different crystal structure. So it's going to hold onto its water; it won't form a neat, readily discerned crystal lattice which means no nice crystals--what you'll get is a very viscous syrup. It is very difficult to remove water from AuCl3, even more so than HAuCl4 (add HCl to AuCl3 essentially) which is a tetrahydrate.

The real, detailed answer is very complex and deals with the interaction of the solvent with the salt. 

Another more extreme example is that of Aluminum (III) chloride, a potent Lewis acid eager to form AlCl4-. Any moisture that gets ahold of this immediately reacts with it, to give HCl gas and hydrous aluminum oxides. 

Lou


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## Harold_V

So then, it's safe to conclude that the vial of gold chloride crystals I had at one point in time, were not just the result of a concentrated solution as I assumed. 

Thanks, Lou. 

I pretty well understood the silver situation----and assumed that gold would react similarly. 

Harold


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## Lou

If you have crystals of ''gold chloride'' coming out of an aqueous system, chances are, it's not gold chloride, but rather HAuCl4, which will be a dark orange red. I have posted pictures of HAuCl4 conc. solution, and freshly made AuCl3 in (IIRC, ether?)


Lou


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## peter i

I can add nothing of value to Lou’s explanation, but will return to the original topic.

After a week of low current in thin silver nitrate, it looked like the photo below. 

There were a single crystal of about 2 by 7 millimetres (just visible in the lover left corner), the rest was a very pretty little trident of approximately 1 mm crystals. Unfortunately, they were not bonded together, but came apart with a gentle pressure.
My parting cell still grows larger crystals!

My next experiment will be even lover voltage in a concentrated solution.


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## Lino1406

This is called: electroforming


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## peter i

Lino1406 said:


> This is called: electroforming



And I dare say it is not! 

This is wild and uncontrolled growth, whereas electroforming is the very controlled homogenous deposition of metal on a mandrel in order to achieve a desired shape or object.
It is possible to work with rather extreme tolerances, so this is definitely not electroforming.

It is electro*depositing*, but we all knew that already.

And it still leaves me with the challenge to grow large single crystals. :wink:


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## Lino1406

and not "wild" crystals, use electroforming
principles, e.g. no brighteners which cause
embrittleness, very narrow voltage range,
and if I'll recall something else, I'll inform


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## austexjwlry

Peter i,

Thank you for posting you're experiments, I'm enjoying them very much!

To duplicate my crystals;
1. Dissolve nearly pure gold in aqua regia
2. Dilute with a few times its volume of water (this may work without diluting with water)
3. Add a large excess of SMB, enough to make the smell of chlorine really rude & offensive upon removing a lid from you're container
4. Boil down until crystals form upon cooling.

This should work in a test tube. I believe Lou is absolutely right about the AuCl3 but for lack of a better term at this point on my part, these do seem to be just AuCl salt type crystals. It seems you may have to boil down enough to remove most of the nitric from solution before they will form.

The general procedure in refining is to boil down first to remove nitric, then precipitate. I added the SMB first then boiled down the very dilute solution which might explain why most refiners haven't created these particular crystals in their boildown pans.

Wayne


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## peter i

Thanks, then it could be sodium sulphate (or the SMB itself!)

Can you smell sulfur dioxide (the pungent smell you describe as chlorine) if you dissolve these crystals in a bit of boiling water?


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## peter i

I refuse to give up!
Especially after the parting cell made larger crystals! :twisted: 

*#4*
I’m going to try with 0.35 V, the concentrated AgNO3 solution and a larger anode.
I cast the anode from refined fine silver in a sand mould, the fine silver behaving much better than I had expected. When used to casting sterling, the look of metal solidifying while staying bright is quite funny.

The micro cell is running now with #4, and if it runs away, #5 will be made with very dilute silver nitrate solution.


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## peter i

#4 was a stinker!
Lots of small cubic crystals.

#5 is now running with the same parameters, except of a 1:20 dilution of the silver solution.


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## draftinu

Peter, got to love your persistence!!!!!!!!!!!!!!!! :wink:


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## peter i

”A persistent nerd is one of the scariest creatures in the forest”

*#5* went sour too
It grew a single thin long strain of crystals from minus to plus, shorting out the cell.

*#6* is running:
The dilute solution from #5, but this time, “minus” is not a single point, but a large single crystal placed perpendicular to the electric field. This seems to make the crystals less eager to “reach” for the anode. (but so far looks like a lot of small crystals)

*In #7*, I’ll minimize the area of the anode, and make the cathode as wide as possible.


Slow nucleation and slow growth should be the key to succes.


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## Oz

Peter,

Progress ???


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## peter i

#6 very slowly grew a lot of small crystals
:evil: 

#7 has not launched yet


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## Oz

Peter,

I have been watching this with great interest, thanks for the update! Off the path you are taking, you had made the comment “Slow nucleation and slow growth should be the key to succes”. It made me wonder if it might be possible to start with a saturated solution at a relatively warm temperature in a shallow glass pan. If you place it in an insulated cabinet with a reasonably accurate thermostatically controlled heating element. Then lower the temperature a half degree every other day or so. A few chunks of lead or even rock in the cabinet would even out temperature swings in the cabinet. Then again the temperature swings if not too severe may even help the growing of large crystals on the warmer end of the temperature swing re-dissolving the smaller crystals back into solution. The larger crystals would not completely re-dissolve but the smaller ones would.


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## peter i

I was thinking about that too.

The “normal way” to achieve super saturation in crystal growing is to lower the temperature (if the wanted substance has lower solubility at lower temp), remove the solvent by evaporation or change the solubility of the substance in the solvent (adding alcohol to an aqueous solution is a classic).
Another approach could be formation of the substance. E.g. A+B-> AB .
If A and B are soluble, and AB has a lower solubility slow addition of a solution of A to a solution of B could give a slight super saturation and a crystal would grow.

There is an energy barrier to nucleation, and the general trick in growing large crystals is to supersaturate enough to make the crystal grow, but not that much as to allow other crystals to nucleate. That’s why slow cooling of a warm saturated solution is normally so successful in growing nice large crystals.

In galvanic processes the supersaturation is caused by the current. And I think one of the problems is, that metallic silver is very insoluble in water. The moment a few silver atoms are reduced, they will clump together to form a crystal.
The growth characteristics depend on the voltage (fine powders of many metals are made by electrochemical means, normally at relatively high voltage), the concentration and the shape of the electric field. Temperature would probably have some effect too, not on saturation but on the way the field shapes and the conductivity of the solution.

I think that the main problem is to avoid unwanted nucleation. Presently it seems like the crystals grow to some size, then stop and others nucleate and grow instead.


… there is quite a bit of black magic in electroplating and electrodepositing!


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## calgoldrecyclers

peter,
try this:
suspend a copper wire into a testube of .1m silver nitrate overnight.
keep in a cool dark place with low noise and movement. by morning you will see crystals!
hint: if you coil the wire or bend in odd shapes, you will get a bigger crystal.


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## Gotrek

calgoldrecyclers said:


> peter,
> try this:
> suspend a copper wire into a testube of .1m silver nitrate overnight.
> keep in a cool dark place with low noise and movement. by morning you will see crystals!
> hint: if you coil the wire or bend in odd shapes, you will get a bigger crystal.



Experiment 15 on http://alex.edfac.usyd.edu.au/Methods/Science/Chemistry%20Demonstrations


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## calgoldrecyclers

see... science is fun!


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## Harold_V

calgoldrecyclers said:


> peter,
> try this:
> suspend a copper wire into a testube of .1m silver nitrate overnight.
> keep in a cool dark place with low noise and movement. by morning you will see crystals!
> hint: if you coil the wire or bend in odd shapes, you will get a bigger crystal.



You can do the same thing, in bright sunlight and Mozart blaring in the background. 

End result? Silver crystals. If you straighten or coil the wire makes no difference. That is the commonly accepted method for recovering silver from a nitrate solution, and is nothing new. 

Remember-----we are men of science, not witch doctors. 

Harold


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## peter i

calgoldrecyclers said:


> peter,
> try this:
> suspend a copper wire into a testube of .1m silver nitrate overnight.
> keep in a cool dark place with low noise and movement. by morning you will see crystals!
> hint: if you coil the wire or bend in odd shapes, you will get a bigger crystal.



Yeah, a classic and the product is crystalline (even made a PXRD just for the fun of it).
But I'm going for huge, mean and nasty crystals in the centimetre range, and I've never seen anything larger than coarse powder from that process (regardless of temperature, concentration and shape/area of the copper plate).

The fun thing is to find the parameters allowing the reproducible growing of large crystals.


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## peter i

#7 Concentrated silver nitrate and 0.1V
Yet another stinker. Lots of small cubic crystal growing in a dense clump.

The positive end was the same old ingot and a pile of silver crystals.




In my mini silver cell, however, nice large crystals are growing. And it seem to prefer growing larger crystals when the dissolving bar is almost gone.

The main differences seem to be:
- Mini cell is operating below 10°C, the micro cell is at low room temperature.
- A large difference in area between growing and dissolving metal. In the mini cell the growing part is the largest, in the micro cell it is the smallest
- Less clean solution in the mini-cell (I'll make a gravimetric test of the actual silver content quite soon)
- larger distance from dissolution to growth in the mini-cell
- pH value will have to be tested too. Acid could prefer eating small crystals, thus favouring the growth of the larger ones.

The fun part will be to find out, what's important.


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## Sylar

What power source are you using for these experiments?

If it's just a transformer with a rectifier bridge you will get a full wave tension, making crystal growth irregular. Try adding a large electrolytic capacitator to flatten out the voltage produced.


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## Anonymous

Dare I say, try adding some common sugar. I read on line (take that for what its worth) in electrowinning or refining cells often have an organic
material added. 

I do not know about the chemistry but electrically, the sugar/organic molecules may interfer with the rapid deposition of atoms allowing time for larger crystals to grow.

I do not t think it could hurt to try, unless there is some problem with silver nitrate and sugar in the same solution. I just suggested sugar because it is common.

Jim


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## Sylar

From a chemical standpoint, sugar poses a risk to reduce the silver nitrate.

Silver nitrate is a pretty powerful oxidiser ...


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## goldsilverpro

I agree. Sugar is not the thing to add. Depending on the metal in question, such grain refiners as peptone, iron free molasses, thiourea, or saccharin can be added. For silver, I know of nothing that should be added, except, in rare cases, tartaric acid.


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## Lou

I know thiourea is the thing for decent copper plating. I also use sulfamic acid every now and then.


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## peter i

I've got test number..... darn, I forgot to count!...

Well, I've got a new one running.

This time I try to keep a large area for deposition, and a small area for dissolving, thus hoping to keep the supersaturation lower.

An attempt to keep the vat stirred with a magnetic stirrer, resulted in long wiry chains of crystal, neatly growing in the stirred direction.

Now it's sitting there growing slowly, mostly small crystals, but hopefully, some of them will soon grow larger.


Power supply used: An old lab-supply that should deliver power as smooth as the skin on (self-moderated).

 
Peter


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## Anonymous

Peter,
What if you took one of the tiny crystals, and used it for a seed. Only that crystal with low current density, so it grows slow and is the only place for the crystal to grow on.

Jim


----------



## Harold_V

james122964 said:


> Peter,
> What if you took one of the tiny crystals, and used it for a seed. Only that crystal with low current density, so it grows slow and is the only place for the crystal to grow on.


I believe that was the reason for success that my elderly friend, now deceased, enjoyed. He grew his large crystals, some weighing several troy ounces, off a pin point only. Seems a crystal would develop at the point and grow larger. 

Harold


----------



## peter i

So far, when I've had a small starting point, the nucleation has been far too violent, resulting in a wiry growth of small crystals.

Low current density, and as an effect of that only a light supersaturation is absolutely the classical way to controlled growth of large crystals. 

Achieving control of the supersaturation is the problem.


So far, the nucleation seem to have stopped, and the crystals are growing.
(and there is an absolutely beautiful branched cluster of shiny crystals)


----------



## shyknee

hello peter i
have you given up on the quest for the abominal silver crystal ?
i really liked reading your updates
i would like to know if you try'd your mini cell under pressure or in a partial vaccume
if not i may give it a try although it may have to wait because of the cold in the garage -0 degrees c last night
hope your well
shyknee


----------



## peter i

I've been hard pressed at work, and that tends to destroy my time off for having fun....I'll get back to it soon (I hope!)


----------



## usaman65

any new updates?


----------



## peter i

usaman65 said:


> any new updates?



No, but I hope to get something started during the x-mas holidays.


----------



## peter i

I've started a new run.

Cast a 140g cylinder from cupper cemented silver powder, covered bottom and sides with hot-melt glue to limit available area to approx 4 square cm
Stood the cylinder on bottom of beaker
Covered with electrolyte (silver nitrate, approx silver content 60g/litre ~0.6 M)
Voltage 0.7 V
"Receiver": 10cm of fine silver wire coiled to a flat spiral
Temperature: ~5°C

The general idea is to limit nucleation to allow continued growth of crystal. Nucleation increases with supersaturation and temperature, and I attempt to counter this with low temperature and low current. So far it has resulted in a lot of small crystals...
:shock: 

I'll let it run until the cylinder has dissolved to see if something happens along the way.

If this indicates that larger crystals are favoured once the area grows larger, I'll try using a piece of silver plate as receiver next time.
(Larger area equals lower current density, again equalling lower supersaturation)

Another option is to increase the silver concentration or use a concentrated copper nitrate solution instead. The last idea comes from the fact, that my refining cell seems to grow larger crystal when the electrolyte becomes contaminated with copper.


Another possibility could be reversing the current for say 10% of the time, in theory preferentially dissolving small crystal.....


----------



## peter i

I was browsing papers and stumbled upon:

Cryst. Res. Technol. I 32 I 1997 1 5 I 637-642 I
R. RASHKOVA, . DASKALOVCAh, r. N. NANEV
Institute of Physical Chemistry, Bulgarian Academy of Sciences 1113 Sofia, Bulgaria
The influence of tartaric acid on the growth kinetics of silver single crystals

It seems tartaric acid inhibits the nucleation, there might be something there!

( http://www3.interscience.wiley.com/cgi-bin/fulltext/112451421/PDFSTART for those with access to it )


----------



## qst42know

Have you experimented with the distance between the anode and cathode to change the shape of the electrical field?

Where I used to work we used a bar magnet to stabilize the arc in a Xenon lamp. The magnet was perpendicular to the arc and as near the bulb as possible. Perhaps you could reshape the field magnetically and get different crystal sizes?

Just thinking out loud.


----------



## peter i

Yes, I've tried changing shapes, and the crystals would grow as the liked anyway (changing the shapes radically).

I've also tried using a magnetic stirrer, which made the crystals grow in a slight bend along the direction of stirring, nothing else.


----------



## qst42know

This is from the reference book GSP posted in the other thread. Found down a couple pages.

"Parting of Bullion.—The electrolytic parting of bullion rich in gold is effected by the same methods. At the Philadelphia mintl a modified Moebius process is used. The anodes (30 per cent. Au, 60 per cent. Ag, 10 per cent. Cu, Pb, Bi, Zn) are encased in cloth bags and hung alternately with rolled fine silver cathodes in an earthenware trough. The electrolyte contains 3-4 per cent. AgN03 and 1-5 per cent. HN03, with certain quantities of dissolved anodic impurities. The current density used is only 0-75 amp./dm.2, and the voltage is low—one volt. A trace of gelatine (1 : 8,000-10,000) is added to the electrolyte. This causes the silver (or nearly all of it) to deposit in a coherent crystalline form, a behaviour rendered easier by the low current density. The metal is exceedingly pure, and the current efficiency approaches 100 per cent. The anodes, after parting, retain their original form owing to the high content of gold. Owing to the large percentage of base metal dissolving, the electrolyte needs frequent renewal."

Could gelatine be the missing piece?


----------



## peter i

qst42know said:


> Could gelatine be the missing piece?



It could yery well be the case. I found a paper describing the effect of tartaric acid in the growth of silver crystals, and it seemed to have a similar effect of inhibiting the nucleation.
Normally I would expect a thin solution of gelatine to be "alive" with bacteria/fungi rather quickly.....but with lots of silver in it, I think that should be taken care of.

My present experiment will be terminated this weekend, it has grown a nice and shiny cluster (or rather a bush) of small crystals.

0.6 M AgNO3
0.7 Volt
Cast ingot with limited surface access
low temperature

I'll recover the crystals and let it continue with addition of a bit of tartaric acid.


----------



## peter i

peter i said:


> I've started a new run.
> 
> Cast a 140g cylinder from cupper cemented silver powder, covered bottom and sides with hot-melt glue to limit available area to approx 4 square cm
> Stood the cylinder on bottom of beaker
> Covered with electrolyte (silver nitrate, approx silver content 60g/litre ~0.6 M)
> Voltage 0.7 V
> "Receiver": 10cm of fine silver wire coiled to a flat spiral
> Temperature: ~5°C
> 
> The general idea is to limit nucleation to allow continued growth of crystal. Nucleation increases with supersaturation and temperature, and I attempt to counter this with low temperature and low current. So far it has resulted in a lot of small crystals...
> :shock: .....



And this is the result of a month of growth:
A bush of very dendritic crystals.
Total weight: 50 grams, meaning there is still 90 grams in the original lump for further experiments.


----------



## Anonymous

Hi Peter,
Its been a while since I checked on this thread. Got a couple questions, have you tried voltage even lower than .7v? or haveing a reversing period of the polarity to redissolve the tiny crystals? do you have a method of stirring the solution? I am very interested as the pictures Harold posted of the large crystals are awesome and I think would be nice to be able to make and maybe even get a premium on the silver content.

thanks
jim


----------



## Anonymous

Flash of inserpation, what if your anode was half a hemispere so that no point of your seed crystal was actually pointed at the anode making the electrical field more uniform and allowing the one seed to grow in all dimensions with a more uniform solution at the same time.

Jim


----------



## lazersteve

Peter,

Beautiful silver you have grown there!

Steve


----------



## peter i

lazersteve said:


> Peter,
> Beautiful silver you have grown there!
> Steve



Thanks, not the crystals I wanted, but certainly pretty. 


Regarding stirring:
Yes, I've tried that, and it only gave the same dendritic growth. The crystals were however showing a tendency to "grow with the flow" rather than forming a symmetric hemisphere.

Reversing the current for short periods of time (say 10% of the total time) is a strategy that I seriously consider. It is however in the department of electronics, and I prefer to test all the possibilities in chemistry before opening a new field of parameters.
In theory it could dissolve newly formed crystals preferentially to the larger well established. "pulse-reverse plating" is quite common in electroplating to ensure uniform layers of metal as far as I know.

(Using tartaric acid has moved a little down the list. According to the papers I've found, quite a bit of tartaric acid is incorporated in the deposited silver, not something I'd like to happen  )

I've tried to change the shapes, but the crystals just seem to grow as they please :| 

An alternative to stirring would be to rotate the negative lead slowly (another technique common in growing large crystals) but this raises a lot of other technical problems. I have some possible solutions, but will prefer not having to use them if simpler solutions are available.


For the next run. I'll simply raise the concentration of silver ions in the cell as much as possible (aka saturated solution)


----------



## peter i

and a picture of the crystal cluster and the silver wire:


----------



## peter i

I've started a new run.

Same set-up as before, but a higher concentration of silver ions (I will have to test to give the exact concentration) and only 10 mm of exposed silver wire for growing the crystals.

I can see them growing, but let's see in a month or so....


----------



## peter i

basically the same parameters, but a much higher (analysis pending) concentration of silver nitrate.

Faster growth, larger crystals!
(Largest 8 by 12 mm)

47 grams total, grown in 18 days.


----------



## pinman

Simply Beautiful, and inspiring.


----------



## butcher

jewlry is worth much more than metal, and those crystals are artwork. 8)


----------



## peter i

Thanks, and yes, they are fascinating.

Reflecting almost all of the light falling on then, they glitter like a cluster of diamonds (I really tried to photograph it, but failed miserably). Thousands of little mirrors pointing in all directions.....

The value as jewellery is unfortunately limited.
- the crystals will tarnish with time
- Very pure silver is pretty soft, and they will easily become scratched, or the rather weak bonds between the crystallites will fail
- soldering them onto something is likely to tarnish them, and it will be hard to regain that "pure crystal plane"-shine

(On the other hand, I have a tendency to make my jewellery in a way that makes it usable as a knuckle duster without deforming.... maybe I should reduce the workmanship and emphasize the "art" using these anyway)


----------



## Irons

peter i said:


> Thanks, and yes, they are fascinating.
> 
> Reflecting almost all of the light falling on then, they glitter like a cluster of diamonds (I really tried to photograph it, but failed miserably). Thousands of little mirrors pointing in all directions.....
> 
> The value as jewellery is unfortunately limited.
> - the crystals will tarnish with time
> - Very pure silver is pretty soft, and they will easily become scratched, or the rather weak bonds between the crystallites will fail
> - soldering them onto something is likely to tarnish them, and it will be hard to regain that "pure crystal plane"-shine
> 
> (On the other hand, I have a tendency to make my jewellery in a way that makes it usable as a knuckle duster without deforming.... maybe I should reduce the workmanship and emphasize the "art" using these anyway)



You have to watch out for people with diamond rings on every finger. The police are wise to that trick. :twisted:


----------



## jimdoc

peter i said:


> The value as jewellery is unfortunately limited.
> - the crystals will tarnish with time
> - Very pure silver is pretty soft, and they will easily become scratched, or the rather weak bonds between the crystallites will fail
> - soldering them onto something is likely to tarnish them, and it will be hard to regain that "pure crystal plane"-shine



Couldn't you seal the crystals in resin and make paperweights or other items that will last forever. I see people selling element samples sealed in resin blocks. Sealing in the crystals to preserve them and their beauty and also to protect the fragility. I know I would buy a paperweight made with your crystals.
Jim


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## peter i

That's a nice point!
(hmmm, I've long wanted to cast other object in resin, must find some now!)


----------



## Toobigfortx

First A Little Background Info:

I'm 23 I've Been Interested In Chemistry Ever Since I First Learned What It Was. However I Have Not Completed My Studies. Presently I Have A Makeshift Lab Set Up I Have Nearly All The Equipment For This Project Of Mine I Just Need Some Helpful Advice/Instruction.

Project(Keep In Mind I'm Still A Beginner)

Purifying Silver To The .9999 Level.

I Have Roughly 5 Pounds Of Silver At .900 Or Better. I Want To Raise It's Level To .9999.
Methods I Know Of are: Nitric Acid + Silver -> Copper (II) nitrate*. And Precipitating .96-.98 Silver

From There I Know I Can Use Electro-chemical Refining From There On, But I Think There May Be Other Ways Of Doing This That Dont Involve Me Having To Buy Or Make Nitric Acid. Seeing As How The Price Of Nitric Acid Is High, As well As Silver Nitrate I Would Prefer Some Information On Alternative Means To Refine The Metal.

Also As A Side Note I Have a Question About The Electrochemical Refining. Can I Just Melt Down The .900 Silver And Still End Up With .9999 After The EC Process Is Finished, Or Will I Have To Use The Nitric Method First? Sorry I Know Its Not In Line With Crystal Growing But I Would Still Like to Learn Both If Possible
_

**Corrected from 'sulfate' to nitrate by Lou. PS--Hereafter, please do not capitalize every single word in Every Single Sentence You Write. It is *very* irksome._


----------



## qst42know

Running .900 silver in your electrolytic refining cell will quickly contaminate your electrolyte as I understand the process.


----------



## Toobigfortx

qst42know said:


> Running .900 silver in your electrolytic refining cell will quickly contaminate your electrolyte as I understand the process.



Thats what I was afraid of. Well then I'll have to go the nitric acid route and use the electrochem to purify. further


----------



## peter i

Toobigfortx said:


> qst42know said:
> 
> 
> 
> Running .900 silver in your electrolytic refining cell will quickly contaminate your electrolyte as I understand the process.
> 
> 
> 
> 
> Thats what I was afraid of. Well then I'll have to go the nitric acid route and use the electrochem to purify. further
Click to expand...


Welcome to the forum.... but when you post something that is not related to a thread, please do it in a separate thread.

This one is about growing large silver crystals, NOT about basic electrolytic refining of 90% silver alloy.
:| 
(Please do not add more "noise" with an apology. You are a new man, and I have forgiven you)


I'm about to terminate the present experiment. It involved using a 6cm exposed wire for crystallisation rather than the previous 5mm (all other parameters equal)
The result is nice but small crystals.... and it ended up growing an "arm" from the cluster to the dissolving lump.

Looks fun, I'll take a picture before harvesting it.


----------



## shelly88813

Wonderful post...


----------



## HAuCl4

Nice, beautiful crystal*s*!. 

Have you tried having just *one* crystal from the beginning and actively trimming all the rest?. It works for vines to make the plant stem stronger!. If there is only one, there is only one!.

I believe the key is slow growth and frequent mechanical pruning (more frequent pruning at the beginning). Try very low voltage 0.25-0.5 V, low concentration of nitrate in distilled water, and cut off mechanically any "branches" that grow from the center crystal as soon at they start.

You'll have to nurture that baby, especially at the beginning when it's weak and small!. :shock:


----------



## peter i

The problem is, that new crystals happily nucleate on the faces of the already formed crystals. Pruning could have some effect, but will not solve the basic question of which parameters will cause limited nucleation and thus growth of large crystals.

My latest experiment has been with 0.6V, saturated AgNO3, low temperature (5-10 °C) quite a bit of copper in the solution and a limited available area of the donor ingot.
....... in general it caused a lot of nucleation an a "rippled" growth.



next experiment will be with the highest possible purity. (and low voltage, large donor area)



And on a side note: 
Sorry for having been absent. I've been overworked due to new job functions (But I'm alive and hope to appear some more in the time to come).


----------



## chefjosh77

A Bit off topic...

If you like Crystals, google "how to make Bismuth Crystals" They are very cool.


----------



## metatp

I am really enjoy my silver cell (thanks Lazersteve). This is the a crystal I made yesterday. I even made one that looked like a horse :lol: .


----------



## peter i

Yup, I've had a lot of crystals growing exactly like that.

They start out with a (often quite long) needle shaped crystal in the middle, and then there is a cubic growth on the sides.

Some examples (sorry for the crappy picture. I only had a webcam handy  )

(squares are 5X5mm)

I'd like the crystal to either continue growing like a needle or a cube. The little game they play about sprouting new crystals is what really annoys me!


----------



## metatp

Nice cryatals peteri. I don't know about you, but I always see different imagine from the crystal. I am sure that if you can get one that looks like Mary crying, you could make a fortune. I see you already made a kangaroo (or is that a dinosaur?).

I tried something new this time and got mostly needles. I went to a 2000ml beaker, but I raised the cathode (SS) to about 3 inches from the anode. That left a 2-3 inch gap under the cathode. To my surprise, the crytal started growing a normal, but tipped over and started growing upside down. I already processed about 900g of cemented silver from that batch of electrolyte before I tried this. The electrolyte was already quite blue.

Regards,
Tom


----------



## HAuCl4

Dunno if this will help, but it's a cool video:

http://www.youtube.com/watch?v=l_USYub3djY


----------



## peter i

@ HTPatch: Yes, it is like a crystallographic Rorschach-test. It's hard not to see shapes and pictures in the crystals.
And the crystal growth seems to have a will of it's own (I guess that is what makes it challenging).

@HAuCl4: That is a very cool video! I have considered slowly rotating the acceptor during the growth, but there are some practical challenges that needs addressing to do that. (The synchronous motor from an "Electric Lamp and Appliance Timer" is my prime candidate, and then some kind of brush to make the electrical connection)


----------



## METLMASHER

Fascinating thread, nice work.
It might be a dumb question but have you used evaporation instead of current on the silver nitrate or does that not occur with that solution?
Time and ambient evaporation (if possible) will give a slow growth but might be just as dendritic as before.
Maybe a semi - conductive as a buffer before (or AS) the cathode will drop the current enough to make a 2 pound :shock: crystal. :lol: WOOHOOO :lol: 
Let me know, I'd like to try some of these experiments soon as I have a better equipped lab. (Less clutter )
METLMASHER


----------



## Harold_V

METLMASHER said:


> Fascinating thread, nice work.
> It might be a dumb question but have you used evaporation instead of current on the silver nitrate or does that not occur with that solution?


Evaporation will yield *silver nitrate *crystals, which are not difficult to grow in the least. What these people are discussing are elemental (electrolytic) silver crystals, which grow under their own terms. I am not aware that evaporation would be useful----it would be no different from raising the amount of silver in solution by other means. 

Harold


----------



## NewBullion

Hi. I grew my first silver crystals this week. I used an anode cast from silver I cemented using copper. I harvested 150g initially, for no particular reason besides curiosity. Very white looking bobbly and spindly crystals. Most broke up upon harvesting.Then I allowed the cell to run non stop until the anode had gone, only to change the filter cloths 3/4 of the way through. Only because there was in my opinion, there was alot of sludge, so just to be sure I made the change. I used 8 layers of polypropylene cloth and no sludge was seen on the underside of the cloths. It took approx 48 hours to run 450g+. Cathode was 304 s/steel sheet. Spacing of electrodes was approx 3.75". 2 litre cell with 200g 999 to make the nitrate. 240ml of Nitric and 240ml of H20 to dissolve the pure 200g and filled the rest with H20 until 2l. The second batch had more "fluffy" looking crystals but not as shiney or white as the first batch. More grey in areas than silver and coral looking. I kept the voltage between 3.1v and 3.7v at all times adjusting but most of the time, voltage was set at 3.5v. Current never exceeded 6A, and averaged 0.4A per sq inch of anode area that faces the cathode. Got down to 0.3A running through the cell by the end. Any ideas as to the colour or fuzziness?

Thanks in advance


----------



## goldsilverpro

Ideally, the crystal should be whiter, shinier, and harder. In a perfectly balanced system, which is almost impossible to achieve, you will dissolve about 4 grams/amp-hr at the anode and deposit 4 grams/amp-hr at the cathode. That way, you would have the same amount of silver in the solution at the end that you had at the beginning. 

I need more info to make a final judgment, but it seems like the anode was less efficient than the cathode and you therefore removed all or most of the silver from the solution. That could be why the amps tapered off at the end. 8 layers of cloth could be too much and could reduce the anode efficiency.

Please note that this is designed to be a continuous system and not a batch system.

Questions:
(1) What was the average amperage over the time period the cell was operating.
(2) After rinsing and drying all the crystal produced, weigh it. This will give you an idea of how much remains in the solution. There is also probably a little in the sludge but it would be hard to determine how much. I wouldn't worry about that.

I would reduce the amperage to about .25 amps/sq.in. (about 35A/ft2) of anode area (only calculate the area of the side of the anode facing the cathode). Since you didn't add any copper to start with and there wasn't much in the bar, this could be a reason for fluffy crystal. Were it me, I would add about 8g/l to start. That's about 1 tr.oz./gal. I would also reduce the layers of cloth.


----------



## Harold_V

goldsilverpro said:


> Since you didn't add any copper to start with and there wasn't much in the bar, this could be a reason for fluffy crystal.


I must (respectfully)_ strongly _disagree. I have years of experience processing silver without the addition of copper to the electrolyte. Never, ever, when starting the cell with fresh electrolyte, did I manage to grow anything but robust, hard crystals, the sole exception being when a hard film of silver would develop. That condition was short lived, easing up as copper accumulated. The resulting crystals were hard, but softened as the copper content increased. Towards the end, when the solution was saturated beyond acceptable limits, only then did I grow soft filaments of silver. This entire sequence was predictable and repeated routinely. I'm convinced, beyond a shadow of a doubt, that a small percentage of copper is used to prevent the formation of hard crystals that rigidly attach themselves to the cathode, so I dismiss the notion that the problem was caused by the lack of copper. I have never found a shred of evidence to support the idea. 



> I would also reduce the layers of cloth.


With that I am likely to agree. My first filter was a *very* heavy, fine weave of cotton, measuring an honest 3/32" in thickness. It was so heavy and tight that I experienced depletion of the electrolyte. 

Harold


----------



## wct0415

Here are some pictures of my latest silver cell crystal growth with experimentation lower voltage and current. The pictures of the crystals were grown in a 24 hour period at .8vdc and current draw was at 1.1 amp average. Unfortunately. when I came home from work the structure had collapsed from the weight of the growth. 

I am going to start a new batch of electrolyte with some crystals from this batch since this one has some copper in solution and to what extent I am not sure. One thing I did notice was when this was complete that my cathode was heavily crystallized and and the crystals were somewhat tannish in color . It was so heavily coated that the only way to remove them was to reverse the polarity of the anode and cathode with out the filter and grew more crystals off the anode bar. I likewise only used one layer of polypropylene cloth as my filter. Maybe this is why my cathode has discolored.

Anyway here are my pictures


----------



## stihl88

Very nice solid crystals their WCT!


----------



## wct0415

stihl88 said:


> Very nice solid crystals their WCT!



Thanks! In my current cell I have another quite large crystal of about 3" long with many other 1.5 - 2" off shoots and are getting quite dense. Will post pictures when harvested.


----------



## stihl88

Keep them coming, you could probably have a go at selling them as is on Ebay with a good margin. I'm willing to bet people would snap them up for their elemental collections etc...

Your cell looks like similar dimensions to mine. I'm going to try and grow some of these fat boys myself, just got to resist turning the voltage up so high :twisted: 
I'll probably have to play around with my cathode dimensions also.


----------



## peter i

Sorry for having been gone for a while, but I've been playing too!

I had almost given up and had started depleting the cell.

The start concentration was 280g silver/litre.
I cut that in half (took out half the electrolyte and refilled with distilled water), reduced with copper, cast a bar and refined it in the cell.
The voltage was 1.2V and nothing special happened (and the bar tested 99.999 in XRF)
I cut it again (it must be around 70g / litre now), and once the bottom of the cell had been covered, this little darling grew out of the mass:




It is my largest crystal so far, and now I have lot of variables to consider:
- The summer has ended here, and the workshop is approx 15 degrees centigrade (lower temperature should decrease nucleation)
- The concentration is decreased, meaning lower electrical conductivity, and thus lower depositing in the receiving end
- lower depositing also means lower supersaturation, and thus less nucleation
- the crystal grew from a large lawn of crystals, and the silver was donated from a relatively small bar. This makes it slower too.
- there is quite a bit of copper in the electrolyte, wonder what that does?

I've restarted with a rod of silver sinking into the basket (rather than a massive bar), 1.2V and the same electrolyte.
I'm exited to see what will happen!


----------



## peter i

I've been busy for a while with anything but refining.

I've restarted the experiments, basically with a reduced set of variables.

Low voltage (50-500 mV range)
Saturated solution of pure silver nitrate (dissolving electrolytic silver tested to be at least 99.999)
Controlled size of donor-ingot

The first conclusion:
Lack of copper does not lead to "fuzzy growth" (I knew that already, but experimental verification is so much more fun)


Grown over a couple of days @ a few hundred mV


More pictures to come


----------



## DONNZ

Beautiful pieces of art.

If not to fragile. 

I do believe the least I'd attempt is dipping one in distilled water to clean, let air dry and give a clear coat of Krylon. 

Should stay shinny and add a bit of strength. 

All kinds of clear acrylic casting and molds out there. I have a crystal in a pyramid. Store bought.


----------



## Topher_osAUrus

Peter, thank you kindly for this thread and your detailed reports of what you have done. This was one of the first threads on the forum I read while studying to set up a silver cell. I have just reread the entire thing again, and hope you find the time to come back and share more with us. But, until then, the search must go on!

After talking the ears off of a couple of my good buddies on here, posting up pictures of my recent run, and then getting called by another member, I figured it would be good to get the input of everyone else as far as their observations and certainties when it comes to the silver cell, and the deposition of silver on the cathode.

(this is going to be a long one... sorry in advance)

So, I initially believed that the deposit of silver on the cathode was determined by several different variables.
*Saturation of electrolyte
--Ag saturation
--Cu saturation
--Other misc elements
*Cathode
--size
--shape
--composition (stainless{grade}, graphite, titanium, et al)
*Voltage
*Amperage
*Anode to Cathode
--size ratio
--distance
##possible variables##
--porosity of anode bag
--surface area of basket blocking path of electricity between anode to cathode(*1)
--temperature
--magnetic properties of cathode?

But, upon reading this thread again, something really jumped out at me, which would be
-path of electricity
Yes, I (kind of) had that in my original guessing game of variables, but when reading it here, something clicked.

(*1)- In my previous cell setup, I had a solid anode that was basically sitting on glass rods, inside of its anode basket. This run, gave me light "barnicle" type growths, they were clustered, but they would have some give if you tried to squeeze them. 

This run, I actually used a platic strainer, that has small holes, maybe a half an inch apart from one another, and this gave me nice thick clusters. While I cannot say for certain that THIS is WHY I got the clusters (I am leaning more towards -my electrolyte evaporated off a good bit of distilled water, and I did not replace it)
But, a side thought
If one were to make a membrane cell, (for simplicity) say 2 palstic tupperware that had a half inch hole in each one where you could connect the two with a piece of pvc or other tubing, and had the anode in one tupperware, and the cathode in the other, would the flow of electrons stick to the constricted path of the tubing, or as soon as it got into the cathode tupperware, would it flare out? (forgive my naivete, I know very little of applied electrical theory)
---and would the length of the pvc between the tupperware have an effect on that as well?
---What if that connecting tubing tapered down to a minimal size? (I do believe that would be troublesome in its own right,[if "yes" is the answer to the electrons flaring out,] as the cathode would have to be very close to the small part of the tubing, leaving no room for growth of the crystals



I know I have also previously posted this picture of silver crystal deposits that was in an electrolysis book I read, where it shows without doubt, that a concentrated solution is most likely the best bet for getting a large dense crystal. BUT, in every one of the pictures, they all had branches to the tree base, and that is not what we are really going for here. 


Although, in the bottom right picture, where it shows a depleted solution, it appears that the crystal gets HUGE, then tapers off into light feathery strings.





I am wanting to replicate the work of Harolds' friend. To hold a single crystal weighing an ounce or more would be incredible.

Other than the loss of water in my electrolyte, and the new anode basket, everything else in my cell was identical. 

I would love to hear input from any and everyone with their experiences on the matter.
Thanks for making it through til the end!

Edit to add pics, fix continuity


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## g_axelsson

One trick in the plating business is to do polarity reversals, that tends to dissolve the fine dendritic crystals before larger. So 5-10% time reversing the polarity of anode - cathode every minute or so ought to produce more dense crystals, or maybe just a dense surface plating.

I think that lower voltages and stirring the electrolyte would also produce more solid crystals as this doesn't deplete the electrolyte further from the anode. Without any movement of the electrolyte the cathode furthest from the anode sees the lowest concentration and also the lowest electrical potential. Electricity always takes the shortest path possible, but resistance counteracts it, so a crystal point close to the anode would see a higher electrical field and more silver atoms would migrate there than compared with a crystal further away from the anode.

In my youth I managed to make some 2 cm large needle sharp silver crystals. As this was my first test of the silver cell I thought "Cool, this is normal." and melted it down... never succeeded to make that large crystals again. :evil: 

Göran


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## Topher_osAUrus

g_axelsson said:


> One trick in the plating business is to do polarity reversals, that tends to dissolve the fine dendritic crystals before larger. So 5-10% time reversing the polarity of anode - cathode every minute or so ought to produce more dense crystals, or maybe just a dense surface plating.
> 
> I think that lower voltages and stirring the electrolyte would also produce more solid crystals as this doesn't deplete the electrolyte further from the anode. ...
> Göran



Peter mentioned trying to stir the electrolyte, and it left with silver branches that grew with the direction of the stir.

I havent been able to find any quantifiable data on people reversing the polarity of the cell and its effect on the growth outcome of the crystals. Silver crystals anyway. It was talked about in this thread earlier, and I can see how it could be beneficial. But, I dont know if it would help to make just one long, solid, crystal. I wont know until I try it, at least.


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## anachronism

Not to go off topic but you can grow gold crystals too.


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## Lou

That's one of Ivan's. Very good chemist!

I believe he also made the osmium crystal for this watch:
http://luxatic.com/hublots-classic-fusion-tourbillon-firmament-osmium-crystal-dial/

Though I can say that I told Hublot _first_ to use it back in 2012 or 2013, in writing 

In any event, we can do a gold crystal thread some other time. The apparatus to make those is somewhat involved but the purities produced are exceptional. As feedstock for making the crystals you posted, I use sponge as prepared under the Ultra High Purity Gold thread.

Lou


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## g_axelsson

Lou said:


> In any event, we can do a gold crystal thread some other time. The apparatus to make those is somewhat involved but the purities produced are exceptional. As feedstock for making the crystals you posted, I use sponge as prepared under the Ultra High Purity Gold thread.
> 
> Lou


Oh yeah, that would be fantastic! Can hardly wait!  

Göran


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## Topher_osAUrus

anachronism said:


> Not to go off topic but you can grow gold crystals too.



That is a very beautiful crystal, but, (besides being gold), it is also done with vapor deposition opposed to electrolysis, correct?
..dont know if I have seen wohlwill crystals though, now that I think about it.

Back to it,
I am getting some silver recovered from chlorides and my latest inquart, and will be using it as an anode to test my split cell idea.

I believe that I will use 2 small tupperware, with a 1/2" pvc connecting the two, but, instead of having the cathode side flush with the cathode tupperware, I will extend it in some distance and with the first test, i will have the cathode (I will probably use a silver wire, with only a point showing) flush with the wall, opposite of the pvc opening (which will extend close to the far/opposite wall of the junction). The second test will be with the cathode point close to the opening on the pvc against the far wall.

I will be using the same electrolyte from my previous run, which has around 130g per L of Ag (maybe more, maybe less), and unknown copper and other contaminants. 

I plan on trying as many things as I can without using additives in the electrolyte. Simply because I don't want to foul it prematurely and have to redo it before its a necessity. Hopefully I can get some progress on the data Peter has so graciously given as a starting point.

For the record, i will continue to use unbleached muslin cloth as an anode bag, doubled up and allowed ample time to get the electrolyte soaked in before turning it on. Voltage will be set at 3.3 and the amps I cant even pretend to guess what they will be, since there are too many open variables at the moment.

Would still love to hear any anecdotal evidence, of crystal growths that any of you have encountered, and what may have been different from the previous batches you ran.


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## Palladium

Silver crystals.
Scanning electron microscope.


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## Palladium

More


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## FrugalRefiner

I made some notes on growing big crystals over the years. It took me a while to find my notes.

Here are some parameters you can experiment with:
Anode to cathode spacing
Cathode surface area ratio to anode surface area
Anode purity
Voltage and amperage
Electrolyte concentration (silver and copper)
pH
Tartaric acid
Magnetic field
Silica gel
Agitation
Cathode shape
Temperature

Dave

Edit to add a couple more possible electrolyte additives that weren't in my notes:
Gelatin (gelatine)
Glue (like Elmers)


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## Topher_osAUrus

Thank you Dave, I was oblivious to a couple of those. Had not heard of the silica gel, or elmers glue being of use. I knew bone glue was a good thing to add into a copper cell, but had not read anything on silver cell effect.

pH is another one that I hadn't really given too much consideration, but in the past, I had added maybe 10 to 20mL all together, of straight nitric. But, I added them to the electrolyte that was IN the anode basket, and not the outside, so its immediate effect was upon the anode. I believe, that if I were to add it to the bulk of the electrolyte (outside the basket), or used a pipette to put it in the bottom of the bowl, it may attack the smaller crystals (I would hope). In practice though, I'm sure the nitric addition would not discriminate and would dissolve pretty much every size and shape crystal.

Agitation, I have tried. A few months ago it was SO cold out, I ended up having to heat up my stainless bowl with an old hair dryer. It gave the electrolyte some motion. To me, it seemed as if the crystals from that one, were nice and smallish, very easy to rinse and dry.

Looking at the scanning electron pictures is beautiful, but it just makes me realize how daunting of a task it is and will be, to find the right set up to grow a single large crystal. It would be interesting to see a couple of the big solid ones posted earlier in this thread, under that microscope. The large crystals, with the flat mirror finish, almost look like smooth metal...although, under the scope, I'm sure their imperfections would be readily seen.

I believe the more important factors will be cathode shape, anode to cathode distance, concentration, current density and voltage, as well as the electrical field.

I can hopefully get my anode melted and poured today. It is going to have quite a bit of palladium in it from the dental gold inquart, so I may be having to redo my electrolyte sooner rather than later. But, that would give me the chance to be more fastidious in my documenting of its contents. And allow me to possibly try a couple of the additive variables.


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## kurtak

The largest crystals out of my last cell run - though I have not weighed them all yet they should all run from 1 gram & up

The 5.6 gram crystal on the scale is also the one in the center of the pic of crystals in the pie plate (as size comparison)

Keep in mind I am - NOT - trying to grow large crystals - these are simply coming out of my cell run at normal parameters - other then I may be running my electrolyte a little more concentrated then considered normal

Edit to add; - the pics don't really do them justice (not the best lighting) the have MUCH more sparkle to them then the pic shows

Kurt


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## Topher_osAUrus

Lovely crystals Kurt! When you squeeze them, do they have a bit of give? Or do they have no budge what so ever? They look nice and dense. Very nice, now, I guess the trick is figuring out how or why they can grow.

An update on what I have been able to try so far

Attempt 1:
I concentrated my old electrolyte down a few hundred mL to have it as saturated as possible. In this attempt, I "kind of" tried the split cell/membrane cell idea, but I was lazy, and that laziness gave my result nothing good in return.


A simple little divided cell I made out of a dollar worth of garage sale tupperware. 


In my haste to get it running, I neglected to seal the barrier to the inside of the larger tupperware, so there was "leakage" of the flow of electricity, and that caused a barnacle growth.
The "path" I wanted it to take, is the tiny little squeeze bottle tip that has been placed in the barrier, that has a pretty small hole in it.

After fail number 1, not only was my crystal a flop, but my electrolyte went foul too from the palladium in my (reclaimed) inquart silver anode. So, with that, I obviously redid my solution (am currently redoing my solution). I also took the whole 5 minutes to hot glue the barrier in place as well as the, uh, nipple?, for the electrons to scoot through and get to the other cathode compartment.

After talking to geedigity again last night about it, I am leaning more and more towards the control of the current, the directionality of it. I keep seeing in my head a "laser" for the flow of electricity that is depositing a silver ion repeatedly in the same spot, instead of (what i interpret in normal use) a ripple effect of the electricity having a tendency to take the least resistant path.

If attempt #1b ends up going bust, I will be toying around with theelectromagnetic effect upon electricity thats flowing through a solution.

I also have another little cell built already, that is of 2 single tupperware, connected by the worlds longest pipette. (believe it has another name than pipette, but its early and I am replying instead of getting my coffee. -idiot!-)


There's got to be a way... Just got to be..


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## kurtak

> Lovely crystals Kurt! When you squeeze them, do they have a bit of give? Or do they have no budge what so ever?



Topher

Here is a close up of them - they start out in the cell as kind of little clusters that over time grow together to become hard & dense & solid - though some will sometimes have a sort of a branch that has a fairly stable grasp but can end up being broke off if you mess with it to much --- so I guess the answer is both - sold with no give - but sometimes a branch (or 2) that can break off if handle to rough

The one on the left is the 5.6 gram one & has such a branch on it - the one on the right is a nice sold piece

For what its worth - the big ones always grow out on the edges of my cathode plate & around the lock nut that locks the negative connecting rod to the plate - they never grow in the center of the cathode plate right under the anodes

Kurt


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## anachronism

They do look lovely Kurt.


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## Topher_osAUrus

kurtak said:


> For what its worth - the big ones always grow out on the edges of my cathode plate & around the lock nut that locks the negative connecting rod to the plate - they never grow in the center of the cathode plate right under the anodes
> 
> Kurt



It's worth a lot to me, Kurt! Thank you again.
For every little detail is pertinent in one way or another.

I did notice, per the underlined, the same on my batch runs. That it seems to have big bunches growing at the furthest point, or (what I would assume) to be the weakest point of current density. 

I'm hoping to have test 1b, and test 2 going today, but washing more than a couple pounds of silver cement is a pain in the rear.

I appreciate you taking the time sir, I know you are a busy man!

Reverting back to what Harold posted on his memory of his friend's cell, I keep thinking, not only direction of electrons but the "closed loop system".

If only I knew what, or how, it was a closed loop system.

Simply closed off to all light, sound, vibration, any variation whatsoever?.. Or a pressurised closed system, much like a cars antifreeze system, etc.. ?..

I'm leaning more toward the former, since he also mentioned somewhere in this thread, that it was in a tupperware, and the cathode was close to the bottom, so the vessel could support the large crystal growth without fracturing the silver chunk.

Much to think about. 
Thanks again dear friends


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## kurtak

Topher

I think you are way over thinking this whole thing with all of the membrane cell, closed loop cell, divided/two chamber cell additives, etc. etc. etc.

There was a local guy that lived about 12 miles from me (he has now moved to Oregon) that was growing LARGE crystals in a "standard" silver cell set up - his cell was a 1 gallon Walmart cookie jar with a SS cathode plate in the bottom & an anode basket hanging at the top

When I say LARGE crystals I mean crystals from 20 grams to as big as 3.5 ozt. (3.5 ozt. was the "biggest" one he grew - which I actually held in my hand) & as well I got to see other large crystals growing in his cell

His crystals looked more like the ones wct0415 posted here - instead of being like my big "cluster" crystals 

:arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=1765&start=90#p107411

only MUCH larger

The "vast majority" of the crystals in his cell where the normal crystals that we are used to seeing grow in a cell (maybe a bit more dense) but he would have 3 - 5 or 6 of the "supper size" also growing

The thing is - I could never get him to tell me just how he was getting those supper sized crystals to grow in the cell - I just know he was doing it because I saw them growing & held them in my hand after he took them out - they where very hard/dense crystals that you could literally throw against the wall without them breaking (I actually saw him do that)

The point is - he was "not" doing it in a "special" designed cell (as mentioned above - it was a gallon cookie jar with a cathode plate in the bottom & anode basket at the top) he was "not" using any kind of additives or growing them from a single pin point as a cathode

So - just how he was doing it I don't know - I just know he was doing it 

I do have some ideas - just have not had time to test them out

Kurt


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## Topher_osAUrus

kurtak said:


> Topher
> 
> I think you are way over thinking this whole thing with all of the membrane cell, closed loop cell, divided/two chamber cell additives, etc. etc. etc.
> ....
> I do have some ideas - just have not had time to test them out
> 
> Kurt



Yes, yes I am. Far too much, on the overthinking.
Its a problem I have.  

What might your thoughts be, as far as the "how"?

A gallon cookie jar probably had a pretty good distance between the electrodes, eh?


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## modtheworld44

Topher_osAUrus said:


> kurtak said:
> 
> 
> 
> Topher
> 
> I think you are way over thinking this whole thing with all of the membrane cell, closed loop cell, divided/two chamber cell additives, etc. etc. etc.
> ....
> I do have some ideas - just have not had time to test them out
> 
> Kurt
> 
> 
> 
> 
> Yes, yes I am. Far too much, on the overthinking.
> Its a problem I have.
> 
> What might your thoughts be, as far as the "how"?
> 
> A gallon cookie jar probably had a pretty good distance between the electrodes, eh?
Click to expand...



Topher_osAUrus


My last silver cell gave me some very nice crystals,But I don't run mine like everyone else does.It's been about 2-3 years since I've run it.I start my cell with less than 20 grams a liter,and I limit my cell by using a single hole of about 1/8 1nch in the center bottom of the anode basket.I use a 12v 3amp regulated power supply and a four quart stainless cylindrical soup dish.The type the restaurants use on a buffet line.I'll have to see if I can find the pictures I took.If I were to re design mine for more dense crystals,I would change the size of the cathode to about a dime.I would also move the cathode about a foot away.

I would also use a narrow but tall container,no wider than my anode basket.This is just my opinion and plans for my next cell.Thanks in advance.



modtheworld44


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## Palladium

Topher_osAUrus said:


> but washing more than a couple pounds of silver cement is a pain in the rear.



What is your process?


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## Topher_osAUrus

Palladium said:


> What is your process?



To wash my cement silver, I usually siphon off all the copper nitrate, then let the silver settle awhile with the vessel tilted, so it compacts in a corner. I slowly turn the bucket, beaker, or whatever Im using and let the copper nitrate continue to ooze out the corner of the compacted cement. Then suction bulb/pipette it up. The removed copper nitrate, goes back to finish cementing whats left (if any).

After satisfied with removing as much as humanly possible (without a filter press), I add enough water to cover the cement, plus just a little more. Heat it up til near boiling, then repeat the siphoning process again. Letting the silver cement compact on one corner, then slowly roll the bottom so it seeps out. These subsequent rinses I save and use as my added water when dissolving sterling or goldfill.

Sometimes it takes awhile for the cement to settle and seep out the rinse waters, but it gets cleaned up in fewer rinses, so I suppose patience is the key. With sterling and inquarts, it has not been a big issue. My problem has come from contact points.

I had recently overshot the nitric because I was fooled by a couple tungston points that had no waffle back pattern. This ended up giving me some cement that likes to float on top. It was difficult to get it to settle, even after breaking up the silver floaters. Lesson learned, the long and hard way. :evil:


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## peter i

I’m still alive :wink: 

It has been 7 years since I last wrote something in here!

Things have been fine (I even published a book about chemical demonstrations last year), but the refining has been somewhat limited.

I ended up having some pretty nice crystals, but not as big as I would like them to be.



In my summer holiday I dusted off some old parts and started cutting and gluing some perspex to make a cell for slow growth with minimal evaporation. It is chugging along at 0.2 volt at the moment.

Nice to see that this thread had posts for years after I “disappeared”.


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## anachronism

That looks fantastic. 8) 8)


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## FrugalRefiner

So, other than minimizing evaporation and extremely low voltage, are there any other parameters you can share?

Dave


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## peter i

FrugalRefiner said:


> So, other than minimizing evaporation and extremely low voltage, are there any other parameters you can share?
> 
> Dave



Minimal evaporation is primarily to avoid having silver nitrate crystals growing all over the place (I wholeheartedly agree with the alchemists for calling it “lapis infernalis”) and to avoid having to top the cell up with distilled water. The lower density made it form a visible layer on top of the silver nitrate solution. 

The question is, whether the beneficial effect of very low voltage really is from the low voltage, or if it is Ohm’s law that gives a correspondingly low current. Growing large crystals is all about having the right super saturation to make the crystal lattice grow, but not enough to overcome the energy barrier to nucleate new crystals.

Placing the donor at the bottom of the cell and the receptor at the top could simplify a lot of things, but even at very slow growth, the solution at the top of the cell was depleted. 

Another test that gave good results was to cast a 25 mm cylinder from fine silver, cover it with hot melt glue to isolate sides and bottom, then standing it upright in the corner of the cell with the acceptor in the opposite corner. Then it would slowly dissolve, at the available area kept constant (like a “cigarette-burning” rocket motor).
The question is again, what really happened? Was it limiting the current that made it slow?


Stirring did not seem to do anything positive.


The silver nitrate solution was made by saturating a 6 M HNO3 with fine silver crystal.
I later used a donor cast from sterling silver, letting the copper concentration increase, but it did not seem to have any effect.

To sum it up:
High concentration and low voltage/current is good.
Limiting the available area to dissolve seems to be good too.
Copper does not seem to make much of a difference.

I have a theory, that a large cell would be better, because it will even out local fluctuations. When the crystals approach the donor, they tend to nucleate more.
But so far, I will be playing with voltage and area.


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## peter i

A couple of pictures of the latest cell:

A vase from IKEA and 5 mm perspex.
The bag is made from non-woven kitchen rag.


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## Shark

Thanks for the update.


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## FrugalRefiner

Thank you for sharing Peter! One of the many projects on my "to do" list is trying to grow some large crystals.

Dave


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## Lou

peter i said:


> I have a theory, that a large cell would be better, because it will even out local fluctuations. When the crystals approach the donor, they tend to nucleate more.
> But so far, I will be playing with voltage and area.




Peter, could you test it with a ramped cathode that is set further away from the anode? I noticed when I used to run cells that the largest and least tree-and-bud dendrites were always the most distant from the area immediately under the anode. We eventually made anode boxes that moved on tracks to lay down a more even deposit, but when I had to push the cells manually at all hours, I started to notice that. Also, anode-cathode gap of course affected the current density upwards and gave lower voltages. I think the best (edited to add) result might be lower current density with AC superimposed on DC. I have seen that done at very large gold Wohlwill setups to get thicker, better deposits. 

What do you think of this design? Lower current density as more cathode area relative to anode but with less flux in concentration of [Ag+] because of phase density differences. I'm surprised stirring did not help but I too have seen DI water sit on top of saturated (1kg Ag/L or more) solutions of silver nitrate.


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## peter i

It absolutely makes sense.

I see something along the same lines.
Things will grow at the bottom, but once something gets ahead, that branch tends to accelerate.

What does not make sense is, that sometimes a crystal decides to grow a lot larger than the other for no apparent reason. 

This is from today:
(Starting to get some color from using copper-cemented silver and a bit of gunk has made its way through the cloth :evil: )


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## Lou

I edited my comment above and dug into some more research. Here's a patent on it:

https://patents.google.com/patent/CA2929515A1/en

that's for copper. Why it's a patent is beyond me as I'm no electrical engineer but it's fairly well known to get smoother deposits and better anode dissolution in a silver and gold cell using that approach.

I think the leading tip of the dendrite tends to grow because the pinpoint/singularity of the growing tip is the closest to the anode and as such will have the least resistance barrier to current/ion mobility-mass transport.

I am not sure, but something about the AC superimposition knocks the leading edges down and fattens the base of the tree. Might be for you to experiment with, I'm already being remiss at work!

Here is a good book on copper refining that talks some about this too (pgs 70-80):
https://books.google.com/books?id=BRVDAAAAIAAJ&lpg=PA75&ots=SGsjaZUz79&dq=what%20causes%20crystal%20formation%20in%20copper%20refining&pg=PA75#v=onepage&q&f=false


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## peter i

Interesting!

I have made an arduino controlled relay, that can switch the direction of the current. Letting it deposit, then reversing for a short time, to dissolve a bit again. Small crystals have more relative surface, and should dissolve readily.

(Not tested yet)


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## Lou

Yes, forced unnatural selection by surface area to mass.


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## Lino1406

It may be interesting for you if you Google for this, and related material


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## Jodokast

I would just like to say thank you to this for forum. I've never posted on here before but I felt this being my best Crystal's to date I would share them. Combined weight of 3.22 Oz.


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## Shark

Jodokast, those are very impressive! I hope to get mine looking like that some day.


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## peter i

Nice!

What conditions were they grown at?


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## Jodokast

It's been a lot of trial and error so its hard to say exactly what perimeters made it grow so well (and continuing to do so in one of my cells). This thread has provided a lot of direction, mixed with lots of hours studying and some luck.


1000ml beaker.


Using a cheap variable bench top DC power supply and have found between 300-450mA to be the sweet spot. With amps set, voltage tends to be anywhere from .4-.8v.


My AgNO3 concentration is difficult to say exactly but after reading Peters post about not having too much to precipitate out as salt because of having to add H2O it clicked in my head. Most crystals are grown in a saturated solution and time to evaporate. So I started with about 7 oz/L then would take the resulting crystals and redissolve them in another beaker and add it until my anode bag began to show AgNO3 crystals on the part above the solution after a day.


I started with a fine cloth for the bag and after a day switched to cloth which had larger thread to allow the ions to flow. (one thing i noticed is if the anode bag/basket has bubbles collecting under the holes you need to change or go lower thread count.)


I have silver shot in the basket with a rod the size of a sharpie marker running down the middle of it attached to my power source.


The cathode is a solid copper wire with a 1cm wide piece of stainless bent over the end and hot glued into place.


The only thing else I can think of is I added a tiny bit of H2SO4 when dissolving the crystal that I added to the electrolyte.

My thoughts are highest saturation possible is good, temperature seems to play a role its been getting colder here in Denver. Power needed can vary and I make slight adjustments on a daily basis. When I did my change out to pull crystals I used some distilled h20 to rinse and that diluted the solution leading to not as good of growth so I heated my electrolyte to remove some h20 and also added some more AgNo3 and its back to looking good. I also have been knocking down the tall ones and they continue to become more dense with time.


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## anachronism

I absolutely love seeing practical solutions like this. It's so simple- yet it appears to do the job beautifully. 

Will your cloth retain the slimes?


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