Formation of fine powder on the surface of the film during weathering, which can cause colour fading. Although some degree of chalking is a normal, desirable way for a paint film to wear, excessive film erosion can result in heavy chalking. Possible Cause:
  1. Use of an interior paint for exterior application.
  2. Over thinnning of paint.
  3. Not properly sealing a porous surface before painting.
  1. Remove as much of the chalk residue as possible, using a stiff bristle brush and rinse throughly with a garden hose; or use power washing equipment.
  2. Check for any remaining chalk by running a hand over the surface after it dries.
  3. Apply a quality primer before repainting.