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CEMENT DUST CONTAMINATION ON P.C. FINISH

September 10, 2008

We fabricate Aluminum railings for condominiums. We have a job where the Powder coated (Polyester)rails were stored on site prior to install. Whilst in storage the rails were contaminated with dry cement & stucco dust. Since install we have experienced blistering, bubbling & flaking of the paint.
Can cement/stucco dust cause a Powder coat job to fail?

  

The PC applicator used a media blast as their pre treatment.

Andrew Benson
metal fab company (buyer)
Cocoa, Florida

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It's a common test for PC to have drops of cement mortar dropped onto the coating, left to dry then knocked off and look to see if there's staining. There should be minimal.

Media blast only as pretreatment sounds inadequate.

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

September 11, 2008

I am not expecting you to know this; but the coater on realising the rails were going to be sited outside, in all weathers, should have applied a zinc phosphate pretreatment prior to the powder application. Powder is not the be all you may think. I would imagine that a small amount of damage occurred in storage. Once the weather got to it, rust creep started to occur. It only needs a slight scratch down to the metal for this to take place. As Geoff states, cement dust etc, would not be the cause of the defects you have noticed.

Terry Hickling
Birmingham, United Kingdom
September 12, 2008