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Black stain spots in satin chrome, plus burning

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Q. Hi, sorry for the bad English.
We are having problems with our decorative chrome. It is causing us some black spots and we also have other burning or flame problems in the material.
We have tried to mitigate by raising the concentration of chromic acid to the maximum, lowering or raising sulfates but so far it has not worked.

Luis Aguilar
- Tijuana, Baja Califiornia
October 21, 2023

A. Hi Luis.
Please send photos to mooney@ for posting here.

The parts look fine after nickel plating? The burning occurs at corners and edges? Temperature of the bath? Are the parts plastic, brass, or steel?

If the chrome is at proper concentration and the temperature is right, maybe you are trying to plate at too high a rate?

Is this a recent problem after a long history of success, or have you never successfully plated this part with this process?
Luck & Regards,

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

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