How to Stop Paint From Cracking in Hot, Dry Weather
Cracking and crazing come down to shrinkage, film thickness and movement. Here's how to specify and apply paint so it doesn't happen — and what to do if it already has.
Shrinkage, Thickness and Movement
Paint shrinks slightly as it cures. In hot, dry conditions that shrinkage happens fast and unevenly, and the film has to be flexible enough to cope.
Thick coats crack because the surface sets while the paint beneath is still shrinking. The result is fine crazing, or the alligator pattern typical of over-applied gloss.
Movement in the substrate adds to it: timber and render expand in the day's heat and contract overnight, and a brittle coating splits at the weakest line.
Thin Coats, Flexible Paint, Cooler Surfaces
Two properly thin coats always outperform one thick one, especially in dry heat. Resist the temptation to build coverage in a single pass.
Choose flexible, elastomeric masonry paint outside and quality acrylics inside — brittle, cheap coatings are the first to craze.
Paint surfaces in shade, ideally in the early morning or later afternoon, so the film cures at a sensible rate rather than flashing off.
Cracked Paint Has to Come Off
Painting over cracked or crazed paint simply reproduces the cracks. The failed film needs scraping and sanding back to a sound, stable surface.
Feather the edges so repairs don't telegraph through, fill where necessary, and prime the exposed substrate before recoating.
Then rebuild in thin coats with a flexible product — the same specification that would have prevented the failure in the first place.
Need Your Empty Property Painted?
Empty Home Painters specialises in painting vacant properties across London.
Get a Fast Quote