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topic 5819

Is There a Test to Detect Chromate (Chem Treat) on Galvanized Steel Sheet


How can I test if galvanized steel sheet has been chem treated (with chromate)? We are painting the steel and need a quick test ,if one exists. As we know paint does not properly adhere to chem treat galvanized steel. We need to test the steel and get an almost immediate response, is there a chemical that changes color when it contacts chromate or a simple test along these lines? help would be greatly appreciated.....

Adam Jackson
- fort lauderdale florida


Dear Adam

Best spot test for chromate is sym-diphenylcarbazide in acidic solution. recommend that you try a o.1% w/v solution of sym-diphenylcarbazide in industrial methyalated spirit, to which 10 % v/v acetic acid is added. Chromate should give an immediate pink color. Alternatively use the chromate detection sticks marketed by Merck an other suppliers. But be sure to acidify before use, as in neutral solution Sym diphenylcarbazide reacts with most metals to give a pink color. Regards

Tom Kinsman
- Burnley, UK

March 14, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Is there a quick test I can do out in the field, on pre-galv sections to check if they are passivated ?

Barry Lyndon
Sales Engineer for MWF manufacturer - BURNLEY

March 14, 2011


Can anyone tell me where I can buy these "Strips" to check for chromate ?

Barry Lyndon
Sales Engineer for MWF manufacturer - BURNLEY

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