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Chromate conversion problem

We have processed parts through our chromate conversion line for numerous years. Recently we came across a problem where the parts had a distinctly different look. the parts in question are Aluminium Impacts. It appears that the waxes used on the impact are imbedded in the parts and do not want to take a conversion coat. We are using all proprietary chemicals (Cleaner, Deox, Chroamte). One customer suggested I add an additional step of Nitric Acid to "cut" this wax. Any thoughts or suggestions

Robert Davis
plating shop - Texarkana, Texas
2005

1. There is no such thing as an aqueous cleaning compound that will remove wax from aluminum without harming the aluminum. You are not allowed to use solvents but your customer is allowed to apply wax!?!?! Cheat and use a solvent to remove the wax from the surface.

2. Then alkali etch to undercut the imbedded wax.

And OH, Nitric Acid will not touch the wax within any time frame that you can afford.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2005

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