Description:

The formation of a powder on the surface of a weathered coating. The powders usually consist of broken down binder and freed pigment particles due to UV, temperature and moisture exposure. Chalking is usually identified by rubbing the surface with a damp cloth which result in a light deposit on the cloth and the restoration of the colour the cleaned surface.

Possible Diagnosis:

• Using interior quality paint for outdoor use.
• Using a low grade paint comprising of a low binder and high pigment loading.
• Most SA medium quality paints are in the 65-75% PVC range and chalking can be expected within 2-4 years.

Remedy:

• Remove the friable chalk by scrubbing with a stiff nylon brush and rinse with water. High pressure equipment can also be used. Check for any remaining chalk after the surface had thoroughly dried. Repeat the cleaning process if powder is still present.
• If chalk persists, repeat with alkali resistant prier / bonding liquid and recoat with appropriate quality top coat.

Recommended Products:

• Top Paints Bonding Liquid Plaster Primer
• Top Paints Water Repellent Latex
• Top Paints Sandcoat