Mods, please feel free to delete if you think this is dangerous, but my thoughts are that anyone who has used etchant knows how to deal with dangerous chemicals and to use gloves and eye protection.
Also the reaction products are less harmful than the reagents.
I found this page:
http://www.phase4c2.com/pic101/pcb/fmc4.htm
and thought I'd give it a try.
If you try this use gloves and eye protection and do it over a plastic tray in case of spills. Have extra water ready in case the reaction goes faster than mine did.
I cut the base from an aluminium can and sanded it to get through the protective coating.
I added about 2ml of water, then 1ml of used sodium persulfate etchant, then a tiny pinch of salt. The reaction started as soon as the salt was added and produced quite a bit of heat, I think it nearly boiled, which is why you need water ready to add to cool and slow the reaction.
I had to scrape the copper from the aluminium with a toothpick after a minute or so to get the reaction to continue.
The amount of aluminium removed from the can is pretty small so there doesn't seem a risk of dissolving through, but that's what the plastic tray is for anyway.
Some equations:
Etching the copper:
Na2S2O8 + Cu = Na2SO4 + CuSO4
Sodium persulfate + copper = sodium sulfate + copper sulfate
Adding the aluminium
3 CuSO4 + 2 Al = Al2(SO4)3 + 3 Cu
copper sulfate + aluminium = aluminium sulfate + copper
adding sodium bicarbonate to neutralise
Al2(SO4)3 + 6 NaHCO3 = 2 Al(OH)3 + 6 CO2 + 3 Na2SO4
aluminium sulfate + sodium bicarbonate = aluminium hydroxide + carbon dioxide + sodium sulfate
On this picture is the copper sludge produced and a drop of the solution afterwards, and before.
The surface of the can afterwards.
Also the reaction products are less harmful than the reagents.
I found this page:
http://www.phase4c2.com/pic101/pcb/fmc4.htm
and thought I'd give it a try.
If you try this use gloves and eye protection and do it over a plastic tray in case of spills. Have extra water ready in case the reaction goes faster than mine did.
I cut the base from an aluminium can and sanded it to get through the protective coating.
I added about 2ml of water, then 1ml of used sodium persulfate etchant, then a tiny pinch of salt. The reaction started as soon as the salt was added and produced quite a bit of heat, I think it nearly boiled, which is why you need water ready to add to cool and slow the reaction.
I had to scrape the copper from the aluminium with a toothpick after a minute or so to get the reaction to continue.
The amount of aluminium removed from the can is pretty small so there doesn't seem a risk of dissolving through, but that's what the plastic tray is for anyway.
Some equations:
Etching the copper:
Na2S2O8 + Cu = Na2SO4 + CuSO4
Sodium persulfate + copper = sodium sulfate + copper sulfate
Adding the aluminium
3 CuSO4 + 2 Al = Al2(SO4)3 + 3 Cu
copper sulfate + aluminium = aluminium sulfate + copper
adding sodium bicarbonate to neutralise
Al2(SO4)3 + 6 NaHCO3 = 2 Al(OH)3 + 6 CO2 + 3 Na2SO4
aluminium sulfate + sodium bicarbonate = aluminium hydroxide + carbon dioxide + sodium sulfate
On this picture is the copper sludge produced and a drop of the solution afterwards, and before.
The surface of the can afterwards.
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