How Does Humidity Affect Painting

Exterior Painting in a Humid Environment

Moisture is always the enemy of an exterior painter. Weather plays a role in every paint job and planning around it is a necessary part of the process. But how does humidity affect painting?

The two most important factors in paint drying are humidity and temperature. If you don’t work with the weather, your paint job could suffer. Avoid extremes to yield the best results.

Humidity

If you live in a high-humidity area, your paint could show surfactant leaching which is brown or white discoloration on your paint. Humidity can hinder the protective qualities of your paint. If you’re painting in high humidity, the new layer may not dry correctly. Moisture in the air impairs the film layer from forming on the paint.

Humidity also wreaks havoc on wood surfaces. If the air was wet prior to painting, the wood could be holding in moisture. When you put the paint on, it seals the water within the wood and causes problems like poor adhesion, rot and mold.

Humidity and Drying

When there is high humidity, the paint drying is put in jeopardy on both acrylic and latex paints. The moisture in the air causes the paint to evaporate more slowly and thus slowing down the dry time. If you experience temperatures that cause condensation, further slowing the drying. In addition, condensation can cause more long-lasting effects like damage to the finish, lifting, disadhesion and paint failure.

Temperature

Closely related to the humidity in the air is the temperature when you paint. If temperatures are cold, they can prevent drying and slow the film from forming. When the mercury rises, paint dries too quickly, causing bumps and blisters along with lifting, cracking and discoloration.

When to paint

It’s best to keep in mind the temperature should be above 50°F for at least 48 hours prior to painting. Allow ample time for rain and humidity to move out and your building to dry before you try to paint.