Recommended Temperatures for Coating

We have all read can labels with recommended temperatures that one should have when coating exterior projects.

NatureColor® label

Our can reads “not to apply in direct sunlight, on hot surfaces, at air temperatures above 90 F or when air or surface temperature is below 50 F or may fall below 50 F four to six hours after application.”

NatureOne® label

Our can reads “not to apply in direct sunlight, on hot surfaces, at air temperatures above 85 F or when air or surface temperature is below 50 F or may fall below 50 F two hours after application.”

It is tempting to “push the temperatures” when the weather doesn’t cooperate. But what happens when one does this?

In the case of temperatures above recommended temperatures, the coating does not get a chance to penetrate into the wood. In other words it flash dries on the surface and could cause adherence problems. Painting in direct sun accelerates drying, as the surface may well be over 90 degrees even though the air temperature is not. Below 50 degrees, the drying sequence of the coating is interrupted and again could cause adherence problems. In the fall one may be trying to finish a project before temperatures fall below 50 degrees.

Choosing NatureOne 100% Acrylic product with its quicker dry time will give you a longer work day and may be the product to use. If you are using NatureColor system, it may be prudent to apply two coats of Base Coat at recommended temperatures and then apply Recoater in the spring rather than to risk coating when temps are below 50 degrees.

Another phenomena, called hazing, can occur when temperatures are cooler and dew forms on the coating before it is dry. Hazing is a whitish appearance in the coating, which does not affect the durability but is cosmetically not pleasing. Hazing can be visually improved by fine sanding the affected area with 220 grit sand paper and then applying a thin coat.