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Silver anode now turns black during Silver Plating

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Need high purity silver anodes

(2005)

RFQ: Dear Sir;

We want to purchase the SILVER ANODE 2.990 Kg PURITY 99.99% Please send the quotation foe mentioned material.

MANOJ DWIVEDI
TRADING CO./ SUPPLIER - KANPUR, UP, INDIA
  ^- Sorry! This RFQ is outdated -^



Silver anode now turns black

(2007)

Q. We are doing Silver plating process on Nuts and bolts to make them anti-seize. Our Tank is Old and solution is checked and additions are made periodically to keep the contents within limits of Standards that we follow. The Tank was working okay in the past But recently we are facing a problem that the ANODE which is Pure 99% Silver starts getting a black film during plating. The black layer on Anode slows the deposit rate and we have to take out the Anode from the bath and clean it using an abrasive pad, rinse and again put it back. We have to do this 3 to 4 times in a 15 minutes plating operation. We have checked the bath for KCN and AgCN and their contents are within limit.
Please suggest any troubleshooting/remedial action?.

Muhammad Najeeb
Plasma Shop Employee - Karachi, Pakistan


(2007)

A. Hi Muhammad,
Silver anodes can be available up to 99.97% of purity. Get that. Change the supplier if he cannot. 50% of your problem will be solved.
Now take care in the following areas:
1.Low free cyanide
2.Low pH
3.More current.
Muhammad why don't you mention the bath composition instead of mentioning "within limit" -- what is the limit!
There is a ratio of metal and cyanide. But first please let us know the "limit" you maintain! Then may be we will help you.
Try to post maximum details rather than leaving things for guessing.
Regards,

t k mohan
T.K. Mohan
    plating process supplier 
Mumbai, India



(2007)

Q. Dear Mohan
Thank you for your suggestions. The Bath Make Composition is Four Chemicals are added in De-mineralized water. These are Potassium Silver Cyanide = 13 Oz.wt./gal, Potassium Cyanide = 10 Oz.wt./gal, Potassium Carbonate = 4 Oz.wt./gal, Potassium Hydroxide = 1 Oz. wt./gal.

Gallon is US gallon = 3.785 Liters.

pH value is 12.5 ,

The Solution Control Limits are Silver Metal = 6.0 - 7.5 Oz/gal (Present value 6.1), Potassium Cyanide = 6.0 - 9.0 Oz/gal (Present value 6.5), Potassium Carbonate = 4.0 - 16.0 (not checked recently), Potassium Hydroxide = 0.5 - 2.0 (not checked recently).

We will look for a 99.97 Silver Anode in our local market. Meanwhile, based on the bath details, if you have any other suggestion please let us know.

Regards
Najeeb

Muhammad Najeebret
Plating Shop - Karachi, Pakistan


(2007)

A. Najeeb,
Can you convert these conc. into g/l!
I am leaving for a holiday. will be back on 15th
Regards,

t k mohan
T.K. Mohan
    plating process supplier 
Mumbai, India



(2007)

A. Muhammad,
You would be careful in following areas if your chemical parameters are in range.
1.filtration of solution
2.quality of cyanide
3.current density
4.quality of water
5.pH of solution

Regards,

Uroj Shahnawaz
- Karachi, Pakistan


(2007)

A. If these anodes were operating OK in this solution until now, then the problem is most likely in the solution. As you indicate that the current is also dropping it sounds like the anodes are polarizing so as your Free cyanide is at the lower end of your range I would try adding a couple of ozs/gal of Potassium Cyanide and see what happens.


Geoffrey Whitelaw, retired chemist
- Port Melbourne, Victoria, Australia


(2007)

A. Hi,

Your Anodes are impure, also not annealed and pickled after rolling. It is probably grease that comes out every 15 mins or so since it can be cleaned by an abrasive. please also check the operating voltage at the bus bars.

deepak whorra Deepak Whorra
     silver craftwork
New Delhi, India



September 11, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I am a supplier of silver anodes to different companies and I have my own melting shop to make these. But I regularly get complaints, that after introducing anode in bath, a few hours later there is some black ingredient coming out from the anode. The crucible which we use for melting silver is made of graphite. Are we using the right crucible or should we use silicon carbide crucible? And also, does graphite get concentrated with silver and result in contaminating the tank? Or is there some other reason for black formation? The most important thing is the testing shows purity of 99.9%.

Darshan Bothra
manufacturer of silver anodes - Chennai, Tamilnadu, India



August 23, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hello all,

When silver anodes are put into the silver bath (Potassium Cyanide base) the anode colour is white. After 5 hours or at the end of the day silver anodes become black. Why?

Is there any impurities in the silver bath or in the anode?

Suggest me.

Surya Narayana
Process Engineer - Tumkur , Karnataka , INDIA.



Silver anode turns black after awhile in a bath with sodium chloride

June 29, 2016

Q. I have a .999 silver plate that continues to get black after a while in solution. It also loses its original mass. How can this be prevented? As I would like to keep plating some things. Will I need to get a new .999 silver plate in the future?

ishmael smith
- Columbus, Ohio, USA

June 2016

A. Hi Ishmael. In silver plating, like most plating, the anode dissolves into solution; that is the source of the silver you are plating onto stuff.

But I don't understand "sodium chloride". This would generate insoluble silver chloride. Perhaps it was a typo or an auto-correct, and you were trying to say "silver cyanide"?

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


June 29, 2016

Q. Hey Ted Mooney. Thanks for taking the time to reply to my question.
Is there any way to make the silver plates get back their original weight. I understand that some of it is being dissolved, but if I get another silver plate and place it in anode and take the worn out won as cathode will I be able to keep re-using my plates instead of buying g new ones. I just would like to restore dome plates

Is there any possible method to do this, I would like to continue plating things for my wife since she would love to have plated utensils. I do not have the capability to buy more silver when it one at a time they wear out. Ishmael smith
- Columbus, Ohio, USA


June 2016

Hi Ishmael. You are plating silver onto other objects. Where do you think this silver that you are plating onto other objects is coming from? It is coming from your silver plates. You can't put silver onto objects without supplying the silver. Where did you learn to do silver plating? Please explain exactly what you do.
For the second time, I don't understand the reference to sodium chloride.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

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