Friday, April 23, 2010

Chalking

Chalking is a fine powdery residue on the paint surface due to decomposition of the paint film. Although some chalking is normal--the natural result of prolonged sun exposure--heavy chalking is a sign of film erosion and causes color to fade.

Chalking 

Causes: 

  • Interior paint was used on the exterior.
  • A porous surface was not adequately primed and sealed.    
  • Overly thinned paint was used.

What to do:

  • Remove as much powder as possible with a stiff-bristle brush and a solution of 1 cup mild detergent to 2 gallons water; rinse well with a garden hose or power washer. Once the surface is dry, run your hand over it to check for residual powder. If a noticeable amount remains, apply a solvent-based primer and repaint with exterior latex. If little or no chalk is detectable and the existing paint job is sound, you don't need to prime before repainting. In fact, you may not need to repaint at all.

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