Metal finishing Q&As since 1989

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Silver Strike Bath

We are having a silver strike bath of 100 liters capacity. We process barrel loads of 650 kgs daily. In a months time the solution turns dark brown giving raise to black pasty stains on the barrel as well as on SS anodes. It gives rise to spotty skip plating also poor adhesion. Kindly explain the reasons and also the remedy.

M. Palaniappan
Plating Shop - Bangalore, Karnataka, INDIA
2005

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Mr.Palaniappan,
Carbon treat the bath once a month.
Give more detailes of your bath chemistry and process adopted.

T.K. Mohan
plating process supplier - Mumbai, India
2005

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Even after Carbon treat the strike bath turns to chocolate brown colour after one days work. We maintain 2 gms/lit Silver metal and 100 gms/lit Potassium Cyanide in the strike bath. All the parts are Cyanide Copper flashed before getting into strike bath.

M. Palaniappan
- Bangalore, Karnataka, INDIA
2005

Ed. note: This letter is almost a repeat of letter 27356, so you may save some time by reviewing that. letter 30484 may also be helpful.

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Do you happen to have baskets with titanium hooks? Check to see if your basket/s are filled to the top with anode.If you are using strike plates, be certin that they are stainless steel. Titainium will burn off into the bath if the current does not have enough anode to pull from. It looks like soapy rust colored bubbles on the surfaceof the bath near the titanium hooks. The sides of the baskets below the surface may appear black and if you remove the basket and place it into a still rinse tank you should see black syrupy strands come of the sides of the basket. This is the titanium I belive. If this is the case, remove the basket from the bath,empty and clean the anodes and the basket (very important). Then leave the strike plates in the bath and dummy plate the bath at a low current for several hours ( I leave it overnight at 5-12 amps).This should help remove any metallic contamination ( Titanium or otherwise). Also look into how you are rinsing your parts after your undercoat plating procces. Dragging other metals into your bath will wreak havoc on your ag strike. One more thing, consider inquiring about the quaility of your potassium cyanide. Good Luck!

Regards,

Michael Null
- Methuen, MA, United States
2005