The Importance of Temperature When Applying a Finish

It is tempting to “push the temperatures” when the weather doesn’t cooperate and we’re trying to complete a project. All application labels recommend the minimum and maximum temperature in which to apply a finish, so what can happen if we don’t adhere to this advice?

When the air temperature is above the recommended maximum temperature (often 90°F) the coating does not get a chance to penetrate into the wood.  In other words it flash-dries on the surface and could cause adhesion problems. Applying a finish in direct sun accelerates drying, as the surface may well be over 90 degrees even though the air temperature is not.  When the air temperature is below the recommended minimum temperature, the drying sequence of the coating is interrupted and again could cause adhesion problems.  Hazing, a whitish appearance in the coating, can also occur when temperatures are cooler and dew forms on the coating before it is dry.  Although hazing does not affect the durability of the finish, it is not visually pleasing. Often, hazing can be visually improved by fine sanding the affected area with 220 grit sandpaper and then applying a thin coat finish. Poor adhesion, however, typically leads to a finish flaking or pealing and will have to be corrected by sanding and reapplying your finish.