# All about anodes and cathodes.



## want2ride (Aug 8, 2011)

I am wondering if we can compile a list of what the different anode and cathode combinations that are used for the different processes, desired voltage range, the reason why it is used for that process, the effectiveness and the electrolyte used in each process. 
Leeching/deplating.... etc.


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## want2ride (Aug 8, 2011)

when its all done i can compile it and put it on a spreadsheet and repost here for archive.


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## goldsilverpro (Aug 8, 2011)

No offense but, to me, that would seem to be a big waste of time and it could take forever. The reason being is that there can be many options for any one system, and the list of possible systems could be very, very long. The electrodes are selected based on what you are trying to achieve and the chemicals involved. You need to find a good text on electrochemistry and study it. I think you're looking for a shortcut where there really isn't one. Once you know the basics, you won't need a list.

I probably have as much or more experience with electrolytic systems than anyone on the forum and I know I'm not going to spend the many hours necessary to formulate what I consider to be a worthless list.


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## want2ride (Aug 8, 2011)

I have a good idea of what i am going to try for my application. I was compiling the list for people to reference. If everyone thinks it is a collossal waste of time i guess this thread won't go anywhere.
Guess we will just have to wait and see if anyone contributes.


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## rusty (Aug 8, 2011)

want2ride said:


> I have a good idea of what i am going to try for my application. I was compiling the list for people to reference. If everyone thinks it is a collossal waste of time i guess this thread won't go anywhere.
> Guess we will just have to wait and see if anyone contributes.



When it comes to anodes and cathodes be it for electroplating or recovery of precious metals you have the best professional opinion your going to get, I don't think there is another member on this forum who has more experience using cells than goldsilverpro.

Like the man said grab a good book on the subject and start reading.

Regards
Rusty


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## want2ride (Aug 8, 2011)

I think you all are misinterpreting the reason for the compilation. I have time to read, in the last 6 months i have read The Real Lincoln, Atlas Shrugged (and anthem), Economics In One Lesson, and i started reading The Fountainhead just before i got started reading this forum and Hoke's book in palladium's sig (about half through) in the last couple days. 

I can read and i have time, i was doing this for everyone's benefit that doesn't necessarily have the time i do. Do you have a specific book to recommend? 

Guess i am on my own for the list. I didn't intend on any individual spending hours on it, i was thinking to start with the basics and go from there.


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## want2ride (Aug 8, 2011)

Does anyone want to see a list or am i wasting my time?


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## Smack (Aug 9, 2011)

I'd look at it. Just keep it simple like starting points for purification of each kind of metal. Like copper, x for cathode, x for anode, x for chemical solution, x for voltage and setup, and so on.


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## Harold_V (Aug 9, 2011)

The real problem with this issue is that electrolytic parting of the vast majority of elements isn't within the capability of the home shop refiner. The problems with electrolyte contamination are difficult to overcome. The sole exception appears to be the parting of silver, and even that is troublesome, in particular when fed low grade silver. Contaminants quickly alter the behavior of the deposition, lowering quality in the bargain. 

I don't think your efforts would be wasted----just not particularly handy for the vast majority of readers. Those of us that have experimented with electrolytic parting learned, long ago, that it's a waste of time. 

Incidentally, I speak from experience. My failure came in attempting to part copper for the recovery of values. That is a losing proposition unless the copper is of high purity in the beginning. 

Harold


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## Lino1406 (Oct 17, 2011)

Such ready lists can be found, e.g. in the book
"Electrochemical engineering" and similar


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## Dr. Poe (Oct 30, 2011)

If you have a specific question, e-mail me and I'll do my best to answer you in a way that you'll understand. Let me know how much chemistry (in years) that you have studied.


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## 4metals (Oct 30, 2011)

Dr Poe,

The whole concept of this forum is public sharing of information. Your soliciting of members to drop you a private e-mail does little to help others learn. 

We welcome your presence on this forum and your years of experience, but if you're here to solicit business, post your information in the business section. If you're here to participate in the open forum even better.


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## Dr. Poe (Nov 4, 2011)

Answering 4metals;
No, you've got me wrong. I don't charge for my information. The reason for a private e-mail is to give very long and detailed answers. I was trying to be considerate.


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## Acid_Bath76 (Nov 4, 2011)

you wouldn't be wasting anybody's time by putting a post like that up. I enjoy reading anything of worth on this forum.


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## Palladium (Nov 4, 2011)

All Free-All The Time

:mrgreen: :mrgreen: :mrgreen:


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## 4metals (Nov 4, 2011)

Dr. Poe

I came to this forum after 30 years in the precious metal refining industry, I knew I knew a lot about the refining industry when I joined, what I didn't know was how much more I could learn from the open discussion that takes place here. Any long detailed answers will be read by a good number of our members, comments will freely flow, and you may begin to look at your own methods in a new light. 

Thanks for posting, you won't be the first to post a long detailed post as many of us have done on this forum. And again Welcome!


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## Dr. Poe (Nov 7, 2011)

OK 4metals, I get it. Still a lot of these guys already have pourbaix diagrams and such. Should I still include them in these discussions? I also found out that there are a lot of the guys that have short cut basic inorganic chemistry. They want to just skip to precious metals refining. There is a lot that just isn't in the text books anymore. Everyone knows that molten gold is so hot that it glows yellow/white. Fewer know that a strong light shone upon the molten gold reveals it to be green.
I wouldn't feel right to give instruction on plating gold via cyanide without listing the safety requirements. 
I caught a man trying to fuse silver oxalate last year. I stopped him before he could kill himself and everyone around him.
I just don't want to give out information that leads one to destruction. I'd rather share what I've learned that's beneficial.
I have in my files, bath compositions for electroplating carat gold hues. Each formula would fill this little box.
I know less about today's computer tech than I should know. I don't even know how to enlarge this box. Dr. Poe


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## Harold_V (Nov 8, 2011)

Dr. Poe said:


> I don't even know how to enlarge this box. Dr. Poe


There is no need. Just continue to add text----the contents scroll, so the box size is, for all practical purposes, to infinity. (It's not really that big---but you're highly unlikely to create a post that it won't handle.)

We have an unspoken policy on the board to discourage posting any process that has unnecessary risks. We also like to point out things that can be dangerous---like involving ammonium hydroxide or alcohol in gold chloride. 

The vast majority of the readers of this forum (myself included) have no formal chemical training-----with there being no shortage of people that fancy themselves creative, so they're always trying something new. Be quick to mention hazards, without giving instructions on how to destroy one's self. 

Harold


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## Lino1406 (Nov 11, 2011)

I take the opportunity offered, Dr. Poe
please explain in your words why molten
gold with strong white light illumination 
gives the green color? Thanks in advance


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## Harold_V (Nov 11, 2011)

Lino1406 said:


> I take the opportunity offered, Dr. Poe
> please explain in your words why molten
> gold with strong white light illumination
> gives the green color? Thanks in advance


A good question----an observation I made as well. 

Harold


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## skdenton (Nov 13, 2011)

Should we change the title of this thread to "The Ethics of Freely Sharing Information"? Lol.... No insults intended, but so far the discussion has not included any concrete information about chemical reactions. Sure you can read a chemistry book and find out what an ideal chemical reaction _should_ look like... But as primarily amateurs without extensive spending accounts, it would be nice to know what easily attained chemicals and equipment in the consumer world yield promising results.


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## Dr. Poe (Nov 13, 2011)

In my own words, maybe wrong, just my guess, nobody asked such a question before now.
I suppose that the surface of the molten gold is dotted with peaks of nanogold floating in yellow gold. Nano gold is blue to black; yellow plus blue makes green. More likely is the presence of trace silver which even 5 9's pure still has a trace.
Dr. Poe


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## Lino1406 (Nov 13, 2011)

why a strong illumination is needed. More likely
every liquid, including gold, has a vapor pressure
what acts as a thin film of gold, giving way for 
green light.
Lino1406,
Author of the e-booklet "Gold enigma 1, 2 or 3
alook inside the electronic shell of noble metals"


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## butcher (Nov 13, 2011)

I wonder:
Colors we see are certain frequency’s (similar to sound we hear from a tuning fork).

I have heard gold smashed flat thin enough, filtered light through it to our eyes and we see the green frequency, would the molten gold reflect these frequencies? 

I would think the brightness of the light wouldn't make much difference unless the (depth or angle??) of the reflection had some thing here.

This is interesting.


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## juliencoin (Jan 8, 2012)

i think the green color has something to do with the molecules being free if you will and something to compare it to would be nano technology or chameleon paint i bet if the light was moved at different angles you may get a different colors


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## Lino1406 (Jan 8, 2012)

Right Julien, however going to nano
in gold, changes color contrary to what is
expected


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## Lou (Jan 20, 2012)

The color of a gold sol or nano particle has everything to do with its particle size distribution.


As to gold's color when illuminated, that is very tough physics beyond me. I'd guess it's probably the way gold reflects light as the temperature increases and it has measurable incandescence due to blackbody radiation. Some sort of scattering phenomenon due to gold atoms produced from its vapor pressure may be a candidate as well. Lithium has a red vapor!

As for gold's color at room temperature, that is easily explained.
http://www.webexhibits.org/causesofcolor/9.html
http://www.fourmilab.ch/documents/golden_glow/

Even seasoned physicists don't like to talk about it.


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## Harold_V (Jan 21, 2012)

butcher said:


> I wonder:
> I have heard gold smashed flat thin enough, filtered light through it to our eyes and we see the green frequency, would the molten gold reflect these frequencies?


if you have access to some gold leaf, look through it at a light source. It will be purple in color. 
If you don't have, pay a visit and we'll take a look at some. I have a few sheets. 

Harold


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## Geo (Jan 21, 2012)

is this why they use gold as filters on the visors on spacesuits? it should filter out ultraviolet light or is it some other radiation it filters?


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## Lou (Jan 21, 2012)

Mostly because it reflects the most of any metal as far as wavelength goes.


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## philddreamer (Jan 21, 2012)

Geo wrote:
"is this why they use gold as filters on the visors on spacesuits? it should filter out ultraviolet light or is it some other radiation it filters?"

Yes, it filters the UV; I used gold coated welding filters some years ago & it helped a lot agaist the UV from welding, much better than the standard filters. 
When I started learning to recover Pm's from the information in this great Forum, one of my first experiments was to put the filters thru HCl/Cl & removed the gold... :mrgreen: 

Thank you GRF!

Phil


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## butcher (Jan 21, 2012)

I have a few of the gold welding lenses for my hoods, but I keep thinking yields would be so small, so I have just kept them for welding.

They use gold in laser mirrors also; I have collected several kinds of these.

Harold, I would like to visit some, and look through gold like a glass, you are one man I would love to meet. Maybe next time I have to make a trip up in that area to get nitric acid, we can make arrangements and visit.

Who knows maybe we could make an arrangement for several of us members to meet each other.

I have looked through gold plated on glass and can see green, who knows it may have a copper under layer.


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## jimdoc (Jan 21, 2012)

Anybody ever recover gold from a 1974-76 Ford heated windshield or backglass?
http://www.glasslinks.com/trivia/trivia3.htm

I have heard they are very rare, and there were people buying them for hundreds of dollars even broken.

Jim


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## philddreamer (Jan 21, 2012)

Butcher, as long as they're not scratched, they are okay, but if they're scratched you run the risk of getting a flash burn.
Mine were from back in the '80's & were scratched, so I experimented with them.

If the get together happens, I would like to meet with you gentlemen, too! 

Phil


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## Geo (Jan 21, 2012)

it is a fact that gold can be hammered so thin that you can read through it and rolled thinner than that.I've seen samples at the U.S. Space and Rocket center in Huntsville Al. its used as radiation shielding on all space going vehicles, even satellites.living in the area, ive seen quite a bit of scrap from Marshall Space Flight Center and worked on the Redstone Arsenal cleaning out warehouses when the space agency went with the shuttle.at the time gold never crossed my mind but thinking back, i know we burned many thousands of pounds of cables with huge connectors in an open pit before the effects of the pollution was common knowledge.


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## butcher (Jan 21, 2012)

Phil I did have you in mind, as I know your up north there close by, it seems there are several of us in this part of the country,

Actually I would like to give you a hand with your dredge sometime, but when the water warmed up and was not as fast and muddy as it is now, I normally use small home made dredges, also if we dived your compressor would have to keep running, I helped my neighbor a few years ago work a 6" dredge, for some reason he wanted to work in deep fast moving water, first time I had ever dredged underwater, the current was so fast we had to anchor every thing down to keep from washing downstream into the rapids, he went first my told me to just keep the motors running they wanted to stall out, so I fiddled with the chock and throttle for a couple of hours while he was underwater, he finally came up and it was my turn, he told me just move slow or you will run out of air, well my wet suit was almost two sizes too small, I had a home made lead weight belt on, with the fastest belt unhook I could make, with junk from may barn, this regulator for air in my mouth and there I go into the cold water pulling my self up to the deep hole in the bottom of the rouge river, huge boulders we were digging under in the river and I was just wondering when one would shift and pin me down there, and sure enough every time I tried to move a big boulder I would find myself with a lack of air and had to slow down, started getting the hang of it after about an hour, and was really enjoying looking behind me and seeing all of the salmon feeding on the water bugs, or craw fish I was moving from there hiding spots, and then I could not breath, well I have been breathing underwater for an hour, and dummy me thinks this thing in my mouth is in the way so I try and get some air from the side of my mouth, well sucking in a gulp of water into my lungs, then figure I better try and get to the surface for air, now struggling with this %$#@ weight belt holding me under water, I found out my quick disconnect was almost not quick enough, I all finally got to the surface for air coughing and puking, and my mining partner neighbor yells I knew you would come up, the air compressor quit running, he found out later his son the mechanic had used the wrong size piston rings when he rebuilt the compressor.

I would like to plan some kind of get together, life is too short not too.


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## philddreamer (Jan 21, 2012)

Butcher... I'm dreaming, I'm dreaming!!! 8)


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## charities (Jan 22, 2012)

DR. POE HAS NEVER ASKED FOR ANYTHING FROM ME. SO IF HE WISHES TO GET TO KNOW AN INDIVIDUAL BEFORE RELEASING HIS KNOWLEDGE THAT SHOULD BE HIS RIGHT TO DO SO... YOU REFFERING TO THE WAY ANYBODY RELEASES THERE YEARS OF TRIAL AND ERRORS, IS AN ATTACK OF YOUR INTEGRITY AS A HUMAN BEING NOT HIS. JUST LISTEN AND DONT GET MAD IF YOU GET LEFT OUT THIS IS NOT RECESS AND YOUR ON THE TEAM OF SCRUBS. THATS ALL I HAVE TO SAY BOUT THAT. WITH THE HELP OF THE DOC I EXTRACTED 3 OZ.OF THE YELLOW GOODNESS FROM SOME SAMPLES OF CALAVERITE AuTe2 I FOUND.


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## butcher (Jan 22, 2012)

charities, 
First let me welcome you to the forum, and share with you a rule we have here, posting in all capital letters is frowned on, it is considered yelling, and the moderators do not allow yelling on the forum. Every body will read what you have to say, better if you do not yell at them.

I am glad Dr.Poe has helped you with you to recover your gold that was very nice of him.
I have no doubt Dr poe is intelligent, and can help people.

My concern is more for the forum, not your gold or myself.

You have just joined the forum so I do not know if you have knowledge of my concern here in this matter or not, I see you are a friend of the Dr.s and wish to defend your friend, I find that noble.

I too hope the good Dr.Poe is a friend, and not a foe.

I wish you well with your mining 
Please let us know your thoughts, on this matter.


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## butcher (Jan 22, 2012)

Nice picture keep dreaming.


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## charities (Jan 22, 2012)

My apologies. I did not realize that my caps lock was on, Thank you for welcoming me to the forum Doc has mentioned you before. I respect the respectable.


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## Palladium (Jan 22, 2012)

Could a moderator compare this posting isp with others? Just a hunch????
:mrgreen: :mrgreen: :mrgreen:


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## Lino1406 (Jan 24, 2012)

I want to put things straight:
Yellow gold is absorbing UV, as well as green 
and blue(about 30-50% reflectivity in that range
meaning 70-50% absorbance).This is why it is 
yellow. The high reflectivity is toward red, infra red.
However if you would like to filter the whole UV 
radiation you'll need several layers. Nanogold is a
semiconductor with thoroughly different gap, that is
why it can be red, pink, blue...
Lino1406,
author of "gold electronic enigma..."


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## Lou (Jan 24, 2012)

Eesh I forgot most of what little I knew about band gaps. I just remember the maths got bad quick when geometry changes. All numerical anyways.


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## VernonBlack (Feb 13, 2012)

Interesting banter on this thread but not much info on anodes and cathodes...Perhaps it should be renamed??....Just saying....


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## lance1 (May 25, 2012)

want2ride said:


> Does anyone want to see a list or am i wasting my time?


whats the best metal for your anodes and cathodes


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## NobleMetalWorks (May 25, 2012)

lance1 said:


> want2ride said:
> 
> 
> > Does anyone want to see a list or am i wasting my time?
> ...



The best metal for anodes and cathodes depends on what electrolytic solution you are using, the type of material you are attempting to part, the distance from anode to cathode, the amps and volts of your power supply, the availability of the metals in your area, the cost of the metals and many other factors.

Why not search the forum for what it is you wan to do, say remove gold plating. Then read the different types of parting cells and the metals used for anode/cathode. Instead of re-inventing the mouse trap, just simply follow the explicit step by step instructions that have been posted, to build and then operate a parting cell.

Scott


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## Woodworker1997 (Oct 27, 2012)

Lou said:


> Mostly because it reflects the most of any metal as far as wavelength goes.




I have taken the reflectance spectra of both gold and silver. It depends on what wavelength you are looking at. Gold is a great reflector but, silver is usually better. Silver coated laser mirrors have a down side though. They work great when new but the reflectance degrades over time. They tarnish. 
CVD gold mirrors last forever until physically damaged. Or if i turn my laser up too high :roll:


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## 98ram (Nov 3, 2012)

Harold_V said:


> The real problem with this issue is that electrolytic parting of the vast majority of elements isn't within the capability of the home shop refiner. The problems with electrolyte contamination are difficult to overcome. The sole exception appears to be the parting of silver, and even that is troublesome, in particular when fed low grade silver. Contaminants quickly alter the behavior of the deposition, lowering quality in the bargain.
> 
> I don't think your efforts would be wasted----just not particularly handy for the vast majority of readers. Those of us that have experimented with electrolytic parting learned, long ago, that it's a waste of time.
> 
> ...




ok this is a little off topic but I deplated some jewelry with sulfuric acid (-) stainless and (+) copper and now what i have is black and red powder and gold at the bottom of the dish so now i do see contaminants are high but I"ve look all over the forums and I cant seem to find how to seperate the gold from the mix is AR my only solution?


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## butcher (Nov 3, 2012)

98ram,
It is not a good idea to put gold into an aqua regia solution with base metals.

I would give the powders a boil in water to wash some of the sulfate.

If there was not tin (or gold fill), you could remove base metals in nitric acid, before going to aqua regia.

If tin is involved, I would wash sulfates, dry, and incinerate the powders, cool, then boil in HCl, rinse with hot water, neutralize with dilute hydroxide and rinse salt well with water, dry, and incinerate again to remove traces of chlorides, before using the nitric acid.


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## 98ram (Nov 4, 2012)

butcher said:


> 98ram,
> It is not a good idea to put gold into an aqua regia solution with base metals.
> 
> I would give the powders a boil in water to wash some of the sulfate.
> ...



ok i thank you greatly butcher for the help. There was some gold fill jewelry. Now Ihave kind of a dumb question I cant seem to find any nitric, HCl, or hydroxide anywhere in the town I live in is there any household products that would do the same? Or I probably could go to a nearby city chemical store just dont want to buy in big bulk since I'm not doing large scale.


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## butcher (Nov 4, 2012)

Check the hardware stores, pool chemical supplier, or where they sell brick, for HCL also called Muriatic acid.

95% tin solder to make your stannous chloride can also be found at the hardware store or where they sell lead free fishing sinkers.

There is no need for nitric acid, or aqua regia if you cannot find nitric, I would not normally use it here anyway.

3% H2O2 hydrogen peroxide, can found in the home drug store area.

Fish tank air bubbler, second hand store.

Bleach sodium hypochlorite NaClO can found be where you buy it to wash your clothes groceries store-cleaning isle

SMB sodium metabisulfite, can be found where they sell beer or wine making supplies, or check in the hardware garden supply, as Bonide brand stump remover is also SMB.

Ferrous sulfate can be made with transformer Iron and sulfuric acid., it can also be found in the garden supply (but all I have ever found in the store was oxidized brown to where it was no good to precipitate gold with, you need nice green crystals)

Sodium hydroxide can be found in cleaning supplies (lye), or in drain cleaners, hardware or cleaning supply or grocery stores.

(Copper II chloride leach also called acid peroxide can be used instead of nitric to remove many of the base metals from the powders).

Check in the second hand store for a corning ware dish or amber violet glass skillet, and solid plate electric hot plate, that and your hand held propane torch.

You can incinerate, and almost complete the whole process in the corning ware casserole dish on a hot plate, using a suction tool and a pipette to remove and transfer liquids from above the powders, the valuable powders stay in the dish almost the whole process.


I would give the powders a boil in water to wash some of the sulfate.

Incineration will not only help to remove sulfate, but it will help to oxidize the tin and other base metals in the powders., the boil in HCl will help to remove the tin and some of the other base metal oxides, the boiling hot water washes will help to remove the soluble lead chlorides.

If tin is involved, I would wash sulfates, dry, and incinerate the powders, cool, then boil in HCl, rinse with hot water, neutralize with dilute sodium hydroxide (lye) and rinse salt well with water, dry, now you can use the copper chloride leach to pick up copper and base metals from the powders, wash the powders and dissolve in HCl/NaClO (bleach) to refine the gold.

I am not stating the minor details in these processes such as filtering and other steps in the procedure. So if you’re not familiar with the processes study them first to avoid many troubles.


You mentioned using nitric and aqua regia so I assumed you had these chemicals, if your not familiar with it aqua regia can be very tricky to use to dissolve gold, HCl bleach is much easier if the material in foils or fine powders.

Not knowing how contaminated your powders are, or the details of your cell, which I assume was the concentrated sulfuric acid stripping cell, it is a little difficult giving advice, but it sounds as though the cell was too dilute and left a lot of copper in the powders.

Visiting Laser Steve's web site and reading the early posts on the cell will help with the sulfuric cell and its proper use, also see the general reaction list and the guide to the forum, in the general chat section.

Using the sulfuric cell properly would eliminate the need to remove copper from the powders at this stage).

Also study dealing with waste in the safety section.

Spending a little time studying can save you a heck of a lot of time dealing with messes, and looking for what happened to all of that gold you had, before putting it into chemicals.


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## 98ram (Nov 4, 2012)

ok I'm going to look into lazersteve's posts and I understand, definelty going to fix my cell so I don't end up with such a mess.


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## zachy (Aug 13, 2014)

Hi there 

What is the method to platinar titanium want to give a bath to coat platinum platinum. as this is done, I've done tests with platinum activating hydrofluoric acid, but I'm missing variables. 
Thank you.


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## goldsilverpro (Aug 13, 2014)

I've used platinized Ti and Ta anodes many 100's of times in PM plating processes but have never attempted to coat them myself. I've always heard that the difficult process is quite dangerous and that some trade secrets are involved. The main problem is to activate the Ti so that the plating will adhere. Most of the processes I've read about used HF for activation and that's where the danger lies. There are several patents. I remember an interesting patent that soaked the Ti for 4 days in conc. HCl and then applied 10 separate coatings of Hanovia Pt, with firing between each coat.

Maybe 4metals has experience with this. If not, I doubt if anyone on the forum could help.


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## Lou (Aug 13, 2014)

Chris, the titanium is etched in H2SO4/ammonium bifluoride, then plated with a P salt bath, then annealed in H2. That's how it's done and I've had good success with it. Using HCl is another method, as HCl will dissolve titanium oxide off the surface. Even sulfuric works quite well, so long as it is air free (SO2 sat'd). Substrate prep, like always with plating anything, is key. 

Part of the danger is in the fluoride, the other part in the P salt, which is the platinum version of gun powder when dry. It is made from K2PtCl4 and sodium nitrite quite easily but do not concentrate it down; best to use as is.

Platinized titanium is cheap enough to purchase, and the anodes commercially available the only justification for doing this is if you need something platinum coated that isn't going to be an anode (in my case, a super alloy). 

Given that zachy can barely make coherent sentences in English, I really would rather not give him a procedure in it.

Lou


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## goldsilverpro (Aug 13, 2014)

Sorry, Lou. I didn't realize that you had done Pt plating.

I just found this patent, 3357858. 
https://www.google.com/patents/US3357858?dq=patent:3357858&hl=en&sa=X&ei=F9nrU6_VNsHB8QG5r4C4BQ&ved=0CB4Q6AEwAA

According to the patent, they got the best adhesion by activating the Ti in boiling 2/1, HCl/HNO3 for 30 minutes. The formula for the mentioned Pfanhauser bath is found on page 195 of this article.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0CEUQFjAI&url=http%3A%2F%2Fwww.technology.matthey.com%2Fpdf%2Fpmr-v32-i4-188-197.pdf&ei=O9zrU8T-LIfLsQT-_gI&usg=AFQjCNEA8ra5IJyKx_SWyeyPpHOM1oCMFw&bvm=bv.72938740,d.cWc


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## goldsilverpro (Aug 14, 2014)

I did a search for Platinum/Titanium anodes, mainly the expanded metal type. It seems there are many manufacturers and there are also many listings on eBay. The pricing is all over the map, ranging from about $4/in2 to $30/in2 (Amazon). The Pt thickness varies considerably, usually from 20 micro" (0.5 microns) to 150 micro" (3.75 microns). I found one listing offering a Pt thickness of 600 micro" (15 microns) but no pricing was given. The actual Pt metal value runs about $0.66/micron/in2, at a $1461 spot price. Pt coated anodes are also available in Tantalum, Niobium, and Zirconium.

Some of the anodes on eBay are used. Used anodes are a pig in a poke since, through usage, the Pt can get thinner. We used to test the anodes by quickly heating a small spot just to red hot with a small torch. If the Pt coating was sound, there was no discoloration after cooling. All the heat did was make it look cleaner. If the Pt was considerably worn off, there would definitely be discoloration. This discoloration was usually blue, if I remember right.

Platinized anodes are used in many industrial electrolytic processes that require the anode to be totally inert. For example, they are almost always used in acid gold plating (pH about 4) and acid rhodium plating. In both cases, stainless can't be used since it would corrode somewhat and contaminate the baths. Bare Ti can't be used because it would form an oxide layer and become passive. Carbon or graphite can't be used because it would slowly erode into small loose particles which would co-deposit and produce roughness on the plated parts. Beside platinized Ti or Ta, about the only other option for acid gold baths would be pure gold or pure Pt anodes, which would be much more expensive than platinized titanium.


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