Friday, April 23, 2010

Efflorescence and Mottling

Exclusive to mortar, brick, concrete, and other masonry. Crusty, white salt deposits that form on the surface are usually a sign of moisture within or behind the substrate. When the moisture evaporates, the salt crystals remain and can cause the paint to peel.

Efflorescence and mottling paint 

Causes:

  • Poor surface preparation.
  • Excess moisture escaping through masonry walls from the interior.

What to do:

  • Before removing the efflorescence, locate and eliminate the source of the moisture--which can mean repairing the roof, cleaning the gutters, and sealing all cracks in the masonry with an all-acrylic or siliconized-acrylic caulk. If moist air inside your home is the cause, install vents or exhaust fans in the kitchen, bathrooms, laundry room, and any other areas where plumbing exists. 
  • To eliminate the salt crystals, scrub with a stiff wire brush and thoroughly rinse with a hose, or use a power washer on the trouble spots. Stubborn deposits can be removed by scrubbing with a 10 percent solution of muriatic acid or white vinegar; be sure to wear protective gear including goggles, rubber gloves and boots. When dry, prime the surface with a masonry sealer and finish with exterior house or masonry paint or elastomeric wall coating. 

Comments

The comments to this entry are closed.