How do I get rid of fine white powder deposits on the wall? What are they?

What is it?

A fine white powder forms on the surface of the finish, usually because of weathering. This can cause the paint to look faded. A little chalking is normal, however heavy chalking can cause the film to wear away. 

What are the possible causes?

  • Applying paint over greasy or very smooth surfaces.
  • Applying over loose dust or rust.
  • Applying over a glossy coat without first sanding it.
  • Applying over partially dried coat.
  • Using a low quality, high-pigment finish.
  • Using indoor finishes on exterior surfaces.

How can I fix this problem?

  • Always prepare surface correctly before painting.
  • Scrub with a stiff brush or wire brush to remove the chalk formation and rinse well.
  • Once it is dry, make sure that all chalk residue has been removed.
  • If the chalking is still present and obvious, use an oil based or acrylic latex primer or sealer. Repaint with a high quality exterior coating.
  • If there is no chalking visible, repaint without using a primer if the old coating is still intact.