• Failure to adequately prepare surface by removing all previous efflorescence
• Excess moisture escaping through the exterior walls from the inside.

Solution

• If excess moisture is the cause, eliminate the source by repairing the roof, cleaning gutters and downspouts and sealing any cracks in the masonry using a quality water-based all-acrylic or siliconised acrylic caulk.
• If moist air is originating inside the building, consider installing vents or exhaust fans, especially in kitchen, bathroom and laundry areas.
• Remove all efflorescence and loose material from the masonry with a wire brush, power brush or pressure washer; then rinse.
• Apply a masonry sealer and allow it to dry completely; then apply a coat of an ultra premium quality exterior house paint or masonry paint.

This information is provided by the Rohm & Haas Paint Quality Institute, www.paintquality.com.au