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-----Sn plating
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Q. Excuse me, I have a Sn plating solution with white visual. These days, the color of the solution is turning violet, which is an abnormal color. What happened to the solution? Is there another reaction of potassium stannate with other metals besides copper?
Marsella Putri- Bandung, West Java, Indonesia
June 15, 2022
A. Hi Marsella. Hopefully a tin plater has seen this before and will comment :-)
The only purple reactions with tin that I have heard of is 'purple of Cassius' which is gold plus tin and sounds very unlikely, and a test for tin ions using Cacotheline, which also sounds unlikely.
But please tell us what kind of tin bath you are operating (acid, alkaline, etc.) because such color reactions are usually pH dependent or Sn+2 vs Sn+4 dependent, so knowing which you are using might be a large hint.
Luck & Regards,

Ted Mooney, P.E. RET
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finishing.com - Pine Beach, New Jersey
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June 2022
Q. I use base solution (K2SnO3)
Marsella Putri [returning]- Bandung, West Java, Indonesia
June 16, 2022
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