Chalking is oxidation of the paint film from exposure to the elements and sun. The breakdown of the paints resin and binder causes a fine powder on the surface. This is a normal weathering process and as paint failures go, this one is the “best” way for a paint to fail. The fix is easy!
- Using a low grade paint without adequate UV blockers.
- Using a paint that uses clay as opposed to titanium oxide in the formula.
- Using a paint that is over tinted, thinned down or not intended for exterior use.
Remove the residue by power washing. Occasionally you may need to use a surfactant to help break the surface tension and remove the chalk. I like “simple green”. It is a very good cleaner and will leave the surface ready to be repainted. Be sure to rinse thoroughly. If after washing you still find chalk on the surface then I would suggest using a high grade solvent based primer.XIM 400 is a good choice.
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