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Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Clear chromate on Aluminum shows brown staining over time
We have been building some Aluminum metal frames for the past few months which are being rejected at our customer facility due to brown staining. Is this a normal reaction with Age? Is my plater not following the right plating process? Any suggestions?
Eran LazarovichCommodity Manager - Markham, Ontario
September 17, 2009
First of two simultaneous responses --
Not much information, so here is a wild guess. Your chem film applicator is staying in the tank for a longer period of time so he can always pass the salt spray test, which gives a darker color. For some reason, they are not rinsing adequately and spots of chem film remain on the part causing a very long reaction time which will give brown spotted parts.
Could be wrong and it would not be the first time.
- Navarre, Florida
September 21, 2009
Second of two simultaneous responses --
Please give us more information. Is the application outdoor or indoor? Has the metal been blasted with media that has also been used on iron? Alloy?
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
September 21, 2009
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