Letter 40026

How do you verify the copper sulphate spot test of passivated steel? [Georgia] 

March 23, 2006

Is there a standard that one could buy that can verify that the solution works properly?
I have performed this test on 300 series steel before passivation and have not seen any indication of copper deposits per my instructions.

Keith Fry
Materials Lab - Valdosta, GA

Keith,

The copper sulphate spot test indicates the presence of free iron on the surface of the steel. If there is no free iron prior to passivation you will not get an indication.
If you want to see if the solution works, try applying it to some mild steel, you should see a reaction in seconds!

Brian Terry
Aerospace - Yeovil, Somerset, UK

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