Adhesion of Powder to Anodized Aluminum
I would like to get your opinion as to using anodizing as a bonding layer for the powder coating or a wet paint application.
Q. I read the comments made to the question of adhesion failure on aluminum in the January 2011 issue and would like to get your opinion as to using anodizing as a bonding layer for the powder coating or a wet paint application. C.B.
A. An anodized aluminum surface is usually used without an organic topcoat. However, some companies want the great corrosion protection from the anodizing and the decorative look of the coating.
I have had inconsistent results with adhesion over anodizing. I am not educated on all of the variables in the anodizing process, so I do not know what impacts adhesion. When it works it is a great finish, but in many cases the anodized surface is not good for powder or liquid bonding.
I would that you do some wet adhesion testing as outlined in AAMA 2605 (American Architectural Manufacturing Association). You do the test the same way as a dry adhesion test per ASTM D3359 (American Society for Testing and Materials) but you place the panel in boiling demineralized water for 20 min after you make the cross hatch cuts and then do the tape pull after the boil. If you can pass that, you probably have a good part
Question: What methods are available for removing cured powder coatings, and what are the pros and cons of these methods?
Masking is employed in most any metal finishing operation where only a specifically defined area of the surface of a part must be exposed to a process. Conversely, masking may be employed on a surface where treatment is either not required or must be avoided. This article covers the many aspects of masking for metal finishing, including applications, methods and the various types of masking employed.
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