Letter 13053

Pickling before chrome plating 

Can anyone advise me on Hard Chrome cleaning. Between sulphuric Acid 30 %and Hydrochloric Acid 30% which does a better cleaning preparation(pickling) for hard chrome before plating ? Thank you so much.

MICHAEL TAN
- Singapore

At room temperature HCl is far more aggressive.

 
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

That is 6 of one and a half a dozen of another. It depends on what metal you are using it on and which one that you like the better. Most platers use a 25 % HCl. Cheaper, less hazardous to make up and I think that it is slightly faster. Drawback fumes-Things around it rust much worse. Sulfuric has far less fumes, is not as corrosive to most metals but generates a massive amount of heat when you dilute it and is an accident begging for a place to happen if someone adds a lot of water to the acid concentrate. The drum is a lot heavier which does not help.

PS, sulfuric is divalent, so for an even comparrison, it is normally used at 1/2 the volume to volume makeup strength of the monovalent HCL.

James Watts
- FL

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