Friday, April 23, 2010

Peeling on Aluminum or Galvanized Metal

When paint loses its adhesion to surfaces such as aluminum screen doors and galvanized steel gutters, poor paint preparation is almost always to blame.

Poor metal adhesion 

Causes:

  • Inadequate removal of rust.
  • Paint was applied without priming first.
  • Failure to clean and/or sand a baked-on enamel finish or glossy surface before repainting.

What to do:

  • Remove all loose paint and rust with a wire brush, then sand rough edges smooth, and wipe the surface clean with a rag and mineral spirits. Apply a corrosion-resistant primer; top with two coats of exterior latex paint. 

  • Fresh-from-the-factory materials, or surfaces that are completely rust-free, can be painted with a 100 percent acrylic latex paint without priming.

Comments

It is important to remove all rust and old paint from the surface. A handy steel wire brush is the best thing to use. If you have an electric sander, that's better. Apply the primer first, then follow it up with latex or elastomeric paint. I prefer elastomeric because it hardens into a rubberized coat that can protect against the elements.

i have a problem that paint pill of from AL 6061 even so wash primer was done and this kind of paint was done on more than 350 units and all pass. we have now 4 units that the paint pills off like it was a like solid paint coming off easy when tested with 3M .
i know in the past we use to coat the part and paint adhesion was perfect but there is a green requirments not to use the anodic coating
please advice

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