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After years of success, powder coating finish now turns fish eyed

I have been having my aluminum railings powder coated for the past 10 years. all of a sudden the shop that is doing my coatings is having problems with the finished product. Its fish eyed. nothing has changed with my material and he claims the same. they wash them in a solution of enzymes. then pre bake at 400 for up to one hour. then the apply the powder and bake it for an hour at 400. the finish is pathetic. we can't figure it out. they then sand the railings down and even sand blast it and go through the same routine. the finish is in some cases is worse. is there something that I can buy to wash them with that will work for sure? when the power coating shop can't answer my questions I have to wonder whats going on. they do have over 14 years experience. any suggestions? these guys have tried every trick in the book that they know and they are baffled as well.

Michael Maguire
fabricator aluminum railings - Ottawa, Ontario, Canada
2007

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Hello, it's going to be hard to find their problem using a 3rd party description, especially for something that can be hard to detect like the origination of a fisheye problem. It sounds like they have oil in their airlines. They've probably told you that they've checked for that already, but if a significant amount of oil gets into the airline you can't just change the filters on the dryer and next to the paint booths and then the problem goes away. There will be residual oil in the conduit and regulators for a long time causing problems, the whole system will have to be flushed to clear it.(If it turns out that that might be the actual problem)Where did they get their book of tricks, I'd like to have one.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
2007

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2007

Hi,
Is the aluminium out gassing? Have they tried to pre-heat the items then powder coat? When they next process your items ask them to coat a test sheet of mild steel at the same time and see if that shows up with the same defect as the aluminium.
Terry

Terry Hickling
Birmingham, United Kingdom

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2007

Something must have changed.

Have you examined your Fabrication process?
Is your finishing crew doing something different or using a new technique? Is there some way that a contaminant is getting on the railings prior to coating?

We once had problems with rust on an aluminum handrail, turned out it was stored (prior to coating but after cleaning) under a shed with a tin roof. The roof had developed a hole and was dripping on the railing. easy to fix if you know whats wrong.

Good luck

Andrew Benson
metal fab company (buyer)
Cocoa, Florida

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2007

Do you check for water break after the enzyme clean? Enzyme cleaners are environmentally attractive but require careful maintenance and a check for efficiency is essential.
If you spray the powder, check the air quality. Take off the air line connection and 'spray' the air onto a mirror surface for 30 sec. Any oil breakthrough from the compressor should be obvious.

Geoff Smith
Hampshire, England

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We are having a high fallout in our production due to the FISHEYE problem.

1) What is the root cause for the fisheye?
2) How to prevent or eliminate this issue?

Please advice.

Thanks,
A.Devan

Devan Arnasalam
powder coating - Johor, Malaysia
December 9, 2009

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December 10, 2009

Hi, Devan. Four people have already offered their thoughts on this subject. Please phrase your question in terms of what has already been said rather than starting over again. Thanks.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey