Electrochemistry Anode Bag Material

[speed]

Im building my first silver cell but one thing I'm unsure of is which meterial I can use to make an anode bag? I have heard vaccume cleaner bags may be sutible for this?

What do you guys use and is there anything to be careful of? I would prefer something I can find easily rather than a specialist fabric.

 

[nickvc]

I believe you can use muslin for it which should be easy to source, the major manufacturers use polypropylene I believe which is woven to allow the solution to pass but the solids/slimes to remain in the bag, depending on how you intend to set your cell up you can use filter cloth under your bars or shot held in a plastic colander.

 

[Shark]

I recently started working on a silver cell as well. I found some polypropylene material that was a bit coarse and caused problems. It also cost me $8 U.S. for 2 square feet. I bought some muslin after getting advice from some other forum members and found that it came in different thread counts as well. I bought the highest thread count that Walmart had on hand and it worked great with two layers. I later tried it with one layer and had no problems. I can get it local for $2.97 a square yard. I also fix my container and press it through the cloth so the silver sits directly on my plastic bowl, which is inside the filter cloth. Doing it this way alleviated some of the problems of disturbing the slime's when adjusting it for better connection when using shot. Wetting the muslin first seems to help getting the cell started off better as well.

 

[anachronism]

I believe you can use muslin for it which should be easy to source, the major manufacturers use polypropylene I believe which is woven to allow the solution to pass but the solids/slimes to remain in the bag, depending on how you intend to set your cell up you can use filter cloth under your bars or shot held in a plastic colander.

Nick can I use that PP filter cloth that I have here?

 

[nickvc]

I believe you can use muslin for it which should be easy to source, the major manufacturers use polypropylene I believe which is woven to allow the solution to pass but the solids/slimes to remain in the bag, depending on how you intend to set your cell up you can use filter cloth under your bars or shot held in a plastic colander.

Nick can I use that PP filter cloth that I have here?

You sure can but use a large plastic colander and lay cloth and the silver inside, use a large stainless bowl and get a power supply and your off and running so long as you have some fine silver to make up the electrolyte 8)

 

[kurtak]

An anode bag is nothing more then a filter

The pours in the filter need to be tight enough that they prevent the "fine" particles of the anode slimes passing through the pours of the filter - if the pours are big enough to allow fine particles to pass through the filter they will settle with the fine silver being deposited a your cathode thereby contaminating your fine silver


Even if the pours are tight enough under normal conditions (the anodes &/or anode bag are NOT disturbed) the anode slims can get "forced" through the filter by disturbing the anode(s) &/or anode bag - so "never" play with you anode basket - bag or the anode material (whether bars or shot) after you have set the cell up & started to run it - wait till you are done running it --- do NOT let cathode crystals grow though to your anode bag - they will poke holes in the bag

paper filters don't work because the fibers break down & fall apart when they get wet

So in reality - any filter material could be used as long as -----
1) the pours are tight enough that the "fine" particles of the anode slimes don't pass through
2) wetting doesn't allow the fibers to break down & fall apart
3) is resistant to the acidic condition of the electrolyte
4) is free of other chemical "residue" (examples - bleached material, cloth washed with soapy water, died material)

out side of that - it really is a question of filter material cost - which is why I believe "un-bleached" muslin is suggested as the go to material for anode bag material - its cheap & can be found at any fabric store

I used to buy my (un-bleached) muslin at Joe Ann's Fabric's but the weave was not real tight so had to use at least 2 layers - if not 3 to insure the anode slimes did not pass through--- recently (a couple years ago) Walmart started selling fabric & their muslin is a heavier tighter weave so that only 1 layer is needed


The other advantage to muslin (being a cotton cloth) is it incinerates to a nice "clean" ash when processing the filters - that's due to the creation of "gun cotton" resulting from the nitrates (nitric acid) used to make the silver nitrate

https://en.wikipedia.org/wiki/Nitrocellulose

I am not sure you would get the same effect with other filter material - which "could" mean you "may not" get complete incineration of your filters - meaning possible carbon in the incineration process rather then clean ash

Kurt

 

[nickvc]

If you use filter cloth the one advantage is that you can put it into acids to remove any powders that are within the weave, bear in mind most of the slimes from a silver cell are silver and not other values so treat them accordingly.

 

[speed]

Thank you for your advice. I will raid the Girlfreinds sewing supplies for some muslin and see how i get on...

I think I'm going to build a cell to use bars rather than shot. It seems easier to maintain electrical contact with bars and less chance of disturbing the slimes or bag when loading. Simple to carefully place the new bars on top of the others as they dissolve.. maybe..

Cell will be a rectangular plastic box with a sheet of stainless in the base for the cathode. A smaller plastic box with holes in the bottom containing the anode bag and anodes will slide along the top of the large box allowing access to scoop out shot without having the disturb the rest of the cell. Simply slide the box along to the other end and remove crystals from underneath.

 

[Shark]

If you use filter cloth the one advantage is that you can put it into acids to remove any powders that are within the weave, bear in mind most of the slimes from a silver cell are silver and not other values so treat them accordingly.

Thanks Nick, looking at the few used filter materials I have now, I understand what your saying. I am waiting now for some new material to retry the polypropylene filter material again.

 

[naporex]

I'm using only PP clothes as anode bag. Currently running 2kg silver bar inside 3 layers of such PP cloth works very well. Earlier I was using 1 layer of PP and 2 layers of filter paper for basket and noticably refining was quicker, but if time isn't an issue I prefer using only PP bag.

 

[Thipdar]

An anode bag is nothing more then a filter

The pours in the filter need to be tight enough that they prevent the "fine" particles of the anode slimes passing through the pours of the filter - if the pours are big enough to allow fine particles to pass through the filter they will settle with the fine silver being deposited a your cathode thereby contaminating your fine silver


Even if the pours are tight enough under normal conditions (the anodes &/or anode bag are NOT disturbed) the anode slims can get "forced" through the filter by disturbing the anode(s) &/or anode bag - so "never" play with you anode basket - bag or the anode material (whether bars or shot) after you have set the cell up & started to run it - wait till you are done running it --- do NOT let cathode crystals grow though to your anode bag - they will poke holes in the bag

paper filters don't work because the fibers break down & fall apart when they get wet

So in reality - any filter material could be used as long as -----
1) the pours are tight enough that the "fine" particles of the anode slimes don't pass through
2) wetting doesn't allow the fibers to break down & fall apart
3) is resistant to the acidic condition of the electrolyte
4) is free of other chemical "residue" (examples - bleached material, cloth washed with soapy water, died material)

out side of that - it really is a question of filter material cost - which is why I believe "un-bleached" muslin is suggested as the go to material for anode bag material - its cheap & can be found at any fabric store

I used to buy my (un-bleached) muslin at Joe Ann's Fabric's but the weave was not real tight so had to use at least 2 layers - if not 3 to insure the anode slimes did not pass through--- recently (a couple years ago) Walmart started selling fabric & their muslin is a heavier tighter weave so that only 1 layer is needed


The other advantage to muslin (being a cotton cloth) is it incinerates to a nice "clean" ash when processing the filters - that's due to the creation of "gun cotton" resulting from the nitrates (nitric acid) used to make the silver nitrate

https://en.wikipedia.org/wiki/Nitrocellulose

I am not sure you would get the same effect with other filter material - which "could" mean you "may not" get complete incineration of your filters - meaning possible carbon in the incineration process rather then clean ash

Kurt

One comment & one question:

If you're discussing filter porosity, I think you mean "pores" instead of "pours".

As for the muslin, do you happen to have a thread count that you know works as an anode bag?

-- Thipdar

 

[g_axelsson]

As for the muslin, do you happen to have a thread count that you know works as an anode bag?

http://www.goldrefiningforum.com/phpBB3/search.php?keywords=muslin+thread+count

The last hit of the search above have a post by an expert. http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=7030#p63113
GSP was one of our best experts on refining here on the forum.

Göran

 

[Thipdar]

As for the muslin, do you happen to have a thread count that you know works as an anode bag?

http://www.goldrefiningforum.com/phpBB3/search.php?keywords=muslin+thread+count

The last post is by an expert. http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=7030#p63113

Göran

Thanks, that will give me a better target to shop for than I was contemplating.

Also, I hadn't considered "sizing" - guess that means I should wash the material a couple of times before constructing the anode bag.

-- Thipdar

 

[rickbb]

Back in the day we always soaked a new anode bag in a solution of sulfamic acid overnight before we would put it in the plating bath.

 

[rickzeien]

Back in the day we always soaked a new anode bag in a solution of sulfamic acid overnight before we would put it in the plating bath.

What was the purpose? Or what did it do? Thanks

Sent from my SM-G950U using Tapatalk

 

[rickbb]

Removed any organics that might contaminate the bath. Organics in a nickel plating bath cause stress in the plate. Especially our operation, we were doing forming, building up a 1/3 mm thick layer of nickel. Any stress would make the part warp like all get out.

 

[rickzeien]

Removed any organics that might contaminate the bath. Organics in a nickel plating bath cause stress in the plate. Especially our operation, we were doing forming, building up a 1/3 mm thick layer of nickel. Any stress would make the part warp like all get out.

Thanks rickbb!

Sent from my SM-G950U using Tapatalk

 

[anachronism]

Yes thanks Rick that one was news to me too. 8) 8)

 

[Geo]

There's some good options here. I haven't used one myself but I am seriously considering the stainless steel filter bags at the bottom of the page.

https://www.dudadiesel.com/filters.php

 

[g_axelsson]

There's some good options here. I haven't used one myself but I am seriously considering the stainless steel filter bags at the bottom of the page.

https://www.dudadiesel.com/filters.php

I would worry that stainless steel would create a metallic screen and shield the anode. It might also be attacked by the current and just dissolve into the electrolyte. On the cathode side the stainless steel is protected by the potential. Even freely hanging pieces is protected by passivization by the acid. But with the voltage potential in the wrong direction I suspect you will have problems.

The other filters looks good, just check the chemical compatibility, if it can withstand aqua regia then you can reuse the filter easily.
I remember when I tried to filter gold foils in nitric acid with a fuel filter... the plastic just dissolved and made a gooey mess with my gold stuck in it. :lol:

Göran