Electrochemistry Can only get coral like silver crystals

[Martijn]

Even at this low current, i can see some convection going down to the largest crystals and moving up again when i move the cathode a bit so that some silver chloride gets knocked loose from the bottom.
So i think the narrow tall cell causes this. There is a concentrated movement of electrons towards the closest point on one side. Towards the tallest crystals, dragging the liquid with it.
Will keep the cell like this to see how things develop.
Looking good so far.

Some kind of heat blanket or tracing cable on one side would certainly make it flow faster. And temperature was mentioned as a positive factor as well. So certainly worth a try.
Martijn.

 

[Nachocucu]

Martijn I love how dense your crystals look.

I can also observe movement within my electrolyte, even with very low voltage.

I have been thinking about how to heat only a small part of the jar to generate more convection. It occurred to me to place a small car bulb on the bottom side of the jar. this way it would not heat the electrolyte too much but it would be enough to generate a convection.
What do you think?

Nacho

 

[stella polaris]

Paint a black spot and let an ordinary lamp heat it up? Or place a resistor on the surface (but that could possibly create too much tensions.)

 

[Martijn]

A small constant heat source can create quite a big flow in time.
Don't know if light is the best way considering the photo effect of silver nitrate. That's with UV light, but you never know.
I would search for a heat trace cable that stays around 25 C. Or slide the heat sink side of your power supply close to the cell.
I think the flow we have from just the current is enough to keep the concentration even throughout the cell.
Had my cel on 0.8 Volts for the night and more fine coral showed up. And some pointy ones grew bigger.
Need more silver. :|
Martijn.

 

[Martijn]

And make sure you put the heater on the side where the flow is already rising, so they amplify each other instead of working against each other.

 

[Martijn]

Update: turned the voltage back to 0.5 Volt yesterday after the crystals started showing coral growth on them. Some got completley covered in it.
One nice arrowhead is sticking out on the left.

It's hiding behind the cathode strip :evil:
Hard to get a good picture so i made two video's of it:
https://youtu.be/_QqlHaCeu2k
https://youtu.be/9kn-XvHvRRE
I'll merge them together later.

 

[Nachocucu]

Martijn your crystals look amazing, they look like cumulus nimbus. Thanks for the tips on heating the electrolyte.

Around here I have been very busy between work and refining. A goldsmith commissioned me to refine some bench silver waste, I had to raise the cell voltage to 3.5 to speed it up as much as possible and thus collect all the silver I have (not much).
In any case, by the end of this week I will be more free and I plan to start again, I have not yet decided if I will assemble the same configuration again but with even more concentrated electrolyte or if I will try to assemble the cell with a 5 liter tall beaker with a low concentration electrolyte (like 75gr / liter).

What do you think is more worth trying?

Here I leave some photos of some crystals that I kept yesterday when I disassembled the cell, nothing impressive.

Nacho

 

[Martijn]

Those are some nice pickers.
To answer your question, it's trial and error. I would try a lower concentration with the same cell.
Maybe keep track of the weights before, after and added silver ( and -nitrate) to see if the electrolyte actually balances out to a certain concentration.

When experimenting its important to change only one variable so you can attribute changes to that variable.
And these results have to be reproducible to be sure.

My cell will run as long as i don't have my tungsten drawplates and new gas and oxy in, from then on it's gold and silver smitting for a while.

 

[kurtak]

or if I will try to assemble the cell with a 5 liter tall beaker with a low concentration electrolyte (like 75gr / liter).

What do you think is more worth trying?

Nacho

IMO I think the 5 liter beaker is a bad idea for a couple reasons

1) beakers are generally made of THIN glass so more likely a better chance of breaking it

2) beakers are tall & narrow so have a relatively small surface area on the floor - so a relatively small cathode surface area

Here is what I have for my cell - its a 5 liter vessel so hold 4 liters electrolyte

:arrow: https://www.ebay.com/itm/Vintage-Glass-Car-Battery-Jar-or-Box-Use-for-Fish-Tank-Bowl-Aquarium

A friend of mine that grew some VERY large crystals used one of these

:arrow: https://www.walmart.com/ip/Anchor-Hocking-Glass-Storage-Heritage-Hill-Jar-1-gal/16486706?wmlspartner=wmtlabs&adid=22222222222009343139&wmlspartner=wmtlabs&wl0=e&wl1=o&wl2=c&wl3=10357840827&wl4=pla-4587437391305441:aud-807612880&wl12=16486706_10000001205&wl14=wall%20mart%20glass%20cookie%20jars&veh=sem&msclkid=3825c7ef70121282b7e2a7f23c519c9b

Both of those are made with much thicker glass & have more surface area on the floor

Edit; - hmmm for some reason the first link is not working --- "try" searching ebay for "vintage glass car battery jar"

Kurt

 

[kurtak]

My cell

 

[galenrog]

Absolutely the best silver cell in all of Grant County.

Time for more coffee.

 

[Martijn]

Little gems hiding in the clouds :mrgreen:

 

[Nachocucu]

Thanks Martijn and Kurt for your advice, I really appreciate it.

Kurt your cell is just great. I would love to find a relatively large source of silver here to be able to refine the amounts that you handle. Here for now I have to move a lot to get a maximum of 600g per month, and that doesn't happen very often.

I am going to restart my cell as it is, just by lowering the electrolyte concentration a little to 200gr / liter. I have some cemented silver to process and can keep experimenting while I process it. I estimate to start it this afternoon, if I can do it I will upload some pictures.

In the meantime, I'm going to try to get a container like the one Kurt recommends, with some patience I will surely be able to find something similar here in Argentina.

Nacho

 

[Shark]

My cell

I am correct in thinking you have added holes to the bottom of your basket?

 

[kurtak]

My cell

I am correct in thinking you have added holes to the bottom of your basket?

The bottom is actually got a plastic 1/4 inch mesh screen in the bottom of it

I cut the solid bottom of the original basket out - leaving enough of a lip to hold the plastic screen in place without the screen falling through by the weight of the anodes

Kurt

 

[Nachocucu]

Hello everyone, two days ago I put my cell back into operation.

Like I said, I concentrated the electrolyte at 200 grams / liter. I used the same electrolyte that I had, took a 100ml sample to check the concentration and then I brought it to the desired value through evaporation.
It has been working these two days in the same parameters and the results have been quite disappointing, only corals have grown vertically with only some crystals a little larger. In any case, I have some silver shot to process so I'm going to continue with the cell as it is to see what happens.

Meanwhile, I'm still looking for a container like the one Kurt recommended, no luck yet. It has occurred to me to use these bottles of wine that are very common here to sell wine in quantity, they are called "damajuanas" and they come from 5 to 20 liters. They are returnable so the glass is quite thick. I think of getting a 5-liter one and cutting its neck.

What do you think? could this work?

Nacho

 

[Lou]

Try low concentration, low current density, low voltage.

 

[Lino1406]

Electroforming from nitrate bath, is best started from a smooth silver cathode base, methanol and tartaric acid added for levelling

 

[kurtak]

Electroforming from nitrate bath, is best started from a smooth silver cathode base, methanol and tartaric acid added for levelling

Per the underlined --- I would not (& do not) recommend adding methanol &/or any other kind of an alcohol to silver nitrate - silver nitrate plus alcohol(s) (methanol, ethanol, etc.) makes silver fulminate

Silver fulminate is an EXTREMELY pressure sensitive "primary" explosive --- it is so pressure sensitive that it can detonate under its own weight & "when wet" - meaning it can explode under its own weight as it precipitates from solution

The pressure sensitivity of silver fulminate is explained on wikipedia as follows -----------

Silver fulminate is a primary explosive, but has limited use as such due to its extreme sensitivity to impact, heat, pressure and electricity. The compound becomes progressively sensitive as it is aggregated, even in small amounts; the touch of a falling feather, the impact of a single water droplet or a small static discharge are all capable of explosively detonating an unconfined pile of silver fulminate no larger than a dime and no heavier than a few milligrams. Aggregating larger quantities is impossible due to the compound's tendency to self-detonate under its own weight.

That said - the fulminate "may not" precipitate at room temp (30 C) --- in the lab "under VERY careful control" of the reaction (to avoid explosion) the precipitation of the fulminate takes place at around 80 C

What that means is that if you have a silver nitrate solution that has had an alcohol added to it - &you put it on a hot plate (such as wanting to evaporate the solution down) it is likely the fulminate could precipitate resulting to an explosion in the lab

Therefore IMO the home refiner should NEVER add ANY KIND of an alcohol to a silver nitrate solution - unless they FULLY know & understand the potential of creating &/or causing an explosion when alcohol(s) are added to silver nitrate

For what it is worth I am a pyro at heart & one of my hobbies (besides refining) is making my own fireworks including making the explosive compounds to make the fireworks :shock: :mrgreen: :twisted:

Kurt

 

[Lino1406]

I think ethanol is meant, but yes, it is good to be careful