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Author Topic: non cyanide silver plating (ammonium thiocyanate?).  (Read 1190 times)

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daginhun

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non cyanide silver plating (ammonium thiocyanate?).
« on: January 04, 2013, 09:15:12 PM »

Hi,
I'm an artist, so no silver plating or chemistry background. I would like to ask for help please to able to start silver plating at home. I would like to use those formulas, which is not using cyanide!
I was reading about this on the internet and I could find a few article and publications about this:

http://infohouse.p2ric.org/ref/18/17422.pdf

http://metalfinishing.epubxp.com/i/49721/244

Both of them using about the same amount of:

silver chloride 30-50g/l
sodium thiosulphate 500g/l
sodium or potassium metabisulphate 30g/l
for pH: sodium bisulphte or hydroxide
0,5A/dm2

I found on the internet, the only problem with this is the poor adhesion, so need to do pretreatment, like use silver strike or for a few min in ammonium thiocyanate.
Ammonium thiocyanate will produce on the polished copper plate: copper thiocyanate. This process will produce any cyanide? During this is any cyanide will go in to the air? What will happen if I can't or can wash it properly and after this I will put the copper plate in to the thiosulphate solution? Is any cyanide will be in the air?
Is any other oxidizer will be fine or need to have copper thiocyanate on the plate for good adhesion?
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Borek

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Re: non cyanide silver plating (ammonium thiocyanate?).
« Reply #1 on: January 04, 2013, 10:55:14 PM »

From what I remember and was able to find, thiocyanates don't decompose easily into cyanides, so I would assume standard lab precautions (thinking, ventilation, gloves, glasses) should be enough to keep you safe. Thiocyanate reactions are commonly used even in HS labs, so the compound seems to be relatively safe.
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daginhun

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Re: non cyanide silver plating (ammonium thiocyanate?).
« Reply #2 on: January 04, 2013, 11:04:30 PM »

So when I create copper thiocyanate on the copper surface or/and If accidently I don't wash it down properly and I put it in to the sodium thiosulphate solution no cyanide gas can produce. Good to hear it. Thank you for your answer!
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Borek

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Re: non cyanide silver plating (ammonium thiocyanate?).
« Reply #3 on: January 05, 2013, 12:53:51 AM »

If it will be just a matter of traces of thiocyanates left on the surface, simple stoichiometry suggests amount of cyanides that could be produced would be insignificant (orders of magnitude below the level at which it becomes poisonous).

All possible disclaimers here - this is at best an educated guess, so in no event treat it as 100% wisdom. Personally I would have no problems following this logic in the lab.
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daginhun

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Re: non cyanide silver plating (ammonium thiocyanate?).
« Reply #4 on: January 05, 2013, 01:12:04 AM »

Thank you!
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daginhun

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Re: non cyanide silver plating (ammonium thiocyanate?).
« Reply #5 on: January 05, 2013, 02:16:44 AM »

just one more thing:
what will happen if I replace ammonium thiocyanate pretreatment with Nitric acid?
What do you think, will this method work as well, or any dangerous reaction can happen with the chemicals above? 
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