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topic 28708

Silver striking problem


A discussion started in 2004 but continuing through 2018

(2004)

Q. Dear Sir,

I am a student. I research about striking silver plating on copper. After plating, quality of coating is not good. White layer appears on coating. Striking composition is:

AgCN 5 g/L
KCN 85 g/L
T 20 °C
Current density 2.5 A/dm2

Please guide me?

Thank you,

Hashemi [last name deleted for privacy by Editor]
student - Esfahan, Iran


(2004)

A. Immerse while the power is on.

Cair Shishani
Cair Shishani
aircraft maintenance - Al Ain, United Arab Emirates



March 23, 2018

Q. Sir,

I have the same problem. I used this solution and immersed with the power on but white layer also occurred. How can I overcome this problem? Can you offer any suggestion?

Caner BASARAN
- ANKARA,TURKEY


March 2018

A. Hi Caner. Are you certain that you used the same silver and potassium cyanide concentrations, worked at the same temperature, did not exceed 2.5 A/dm2, and are only trying to strike the copper with silver, not to actually silver plate it (plating it for 30 seconds or less)?

Digital version
mfg_online

(No longer published, but Elsevier hasn't yet de-commissioned the online version of the Guidebook)
Download it before it disappears.

Sometimes when people say they have 'the same problem', they just mean they also got unacceptable results like the original poster -- not that they carefully adhered to every other point of the original question. If you did some things different, and don't tell us what they were, it can be very difficult to help :-)

But actually, maybe you should try a lower current density because Lowenheim's "Modern Electroplating" [link is to info about book at Amazon] suggests 1.0-2.0 A/dm2 and the Metal Finishing Guidebook suggests 0.5-1.0 A/dm2 =>

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


March 26, 2018

Q. Sir thank you for your reply,

I used 1.883 A/dm^2.

I used below ingredients with 150 ml solution.

3 gr KAg(CN)2
4.5 gr Potassium cyanide
3 gr Potassium carbonate.
at room temp.

I did our experiments with 3.3*3.1 cm coupons with forty minutes (approximately 8 micron thickness).

All of my coupons plated with white, not gray, color.
I didn't solve my problem. I boiled my coupons in water for two hours, but I could not solve the cyanide compounds on the surface.

I did not use strike solution, I used rack work solution.

Please help me.

Caner BASARAN [returning]
- ANKARA,TURKEY


March 2018

A. Hi Caner. I wouldn't expect you to realize it, but this site has been running for 23 years and has a quarter million metal finishing postings arranged under 50,000 topics. So we have many threads which address your actual problem of heavy silver plating for 40 minutes much better than this one which was about the completely different process of silver striking for a few seconds.

For starters, you seem to be attempting to do silver plating without any addition agents but are surprised by the resulting white deposits, whereas Alan Blair notes on the first page of his 'Silver Plating' chapter in the 'Metal Finishing Guidebook' ...

"The formulas above [similar to yours] will produce chalk-white deposits that are very soft. Additions of grain refiners or brighteners will modify deposits, causing them to become lustrous to full bright".

Blair also notes on page 2, that ...

"... it is essential to employ a silver-strike coating prior to plating ..."

Please review at least the silver plating chapter of a plating text before doing anything further. You have not introduced yourself so we also concerned about whether this use of truly deadly potassium cyanide chemistry is being done under adequate supervision. Good luck!

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


March 27, 2018

A. I'm not sure what your problem is but, as far as I know, silver is the whitest metal there is.

Chris Owen
- Benton, Arkansas, USA



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