Letter 4063

Hobbyist is getting blackish coat from Chrome plating 

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Sir:

I'm a hobbyist (new) and have problems with chrome plating.

My bath is composed of 250 g chromic acid/liter and sulfuric acid 3.5 g/l using 6-12 v but I got a blackish coat over my piece as a result.

Please send me your suggestions as to what I must do.

Thank you very much and regards.

Alex

Alex Bautista
- Philippines

March 1, 2009

Hi, Alex. Are you trying hard chrome plating or decorative nickel-chrome plating?

What temperature are you trying to plate at? What current density? You do know that your sulfuric acid is on the very high side of feasible, if feasible at all, with a ratio of 71:1 instead of the suggested 100:1?

What instructions are you following so we can guess what kinds of things you may be missing? Better yet, try a plating text like the Metal Finishing Guidebook or the Electroplating Engineering Handbook, to see the basics. Thanks. Good luck!

Regards,


Ted Mooney, P.E. 
finishing.com
Brick, New Jersey

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