Coating thickness is only one factor that affects the drying time of acrylic and latex paints. Humidity and temperature are two environmental factors that have a great impact on the amount of time it takes for a coat of paint to fully dry.
If the air is loaded with water vapor, the water in the paint cannot evaporate as readily. This slows down drying times. If the paint is exposed to excessively high humidity, the desired protective qualities of the paint may be compromised.
High humidity also works against a fresh coat of paint by re-introducing water into the incompletely dried paint film. Combine high humidity with low temperatures, and condensation develops on the freshly painted surface, which can mar the paint job.
Acrylic and latex paints dry the best within a narrow range of temperatures, between 65 to 85 degrees Fahrenheit. At lower temperatures, the pigments are unable to coalesce properly, which compromises the quality of the finished job and cuts into the lifespan of the paint. At very low temperatures, the water in wet paint can freeze, which effectively ruins the paint.
High temperatures, especially when caused by direct sunlight, can lead to blistering. This effect occurs because the intense heat of direct sunlight causes the compounds in the paint to vaporize, building pressure under the paint layer until the wet paint bubbles away from the substrate.
Other kinds of paint have different factors that influence their drying times. Coming up we will examine what hurts the drying time of two commonly used industrial paints: epoxy and elastomeric coatings.