When exterior paint begins to wear out, it shows signs of chalking by forming a powdery residue that easily rubs off. While the chalking may not be immediately obvious, when noticed, it shouldn’t be ignored. If left long enough, the paint will take on a washed out appearance, leaving your home looking shabby.
Below are some of the reasons why your exterior paint may begin to chalk:
Excessive sunlight: The ultraviolet rays in sunlight can cause the binders in the paint to break down, releasing the paint pigments in the process.
Oxidation: When the oxygen in the air reacts with the binders in the paint, it causes them to oxidize. When the binders become oxidized, they begin to break down; this breakdown results in chalking.
Type of paint: Oil based paints oxidize more readily than acrylic paints. For this reason, acrylic paints are better suited to outdoor painting.
Quality: It is true that you get what you pay for; cheaper paints will oxidize and degrade more quickly than quality paints.
Over thinning: If too much thinner is applied to exterior paint before application, it will make the paint susceptible to chalking.
Overspreading: When painting a surface, if the paint is overspread, it will also make the paint susceptible to chalking.
Even with high quality paint, any of the above processes can eventually wear your paint down. Although chalking is a sign that your paint is weathering, it is a less problematic method of weathering than peeling. Nonetheless, chalking can create problems if left unchecked for too long. For instance, severe chalking can make it difficult to repaint your walls because of the porous nature of the chalking residue. This residue will affect surface tension and prevent adhesion of paint to the surface.
To solve the problem of chalking, here are some steps to take:
Determine the degree of chalking by rubbing a piece of cloth against the surface to see how much residue comes off.
Mild chalking can be solved by wire brushing, while moderate or severe chalking may require pressure washing or sand blasting.
After the surface dries, check to see if the paint is still in good condition. If it is, your work is done; if not, you will need to prime the surface in order to improve appearance.
Often the best solution is to repaint the entire surface.
Remember that, if properly controlled, chalking can provide a good surface for repainting. With proper attention, and the right treatment, your home will regain its curb appeal in no time.