Drying occurs when solvents evaporate from the surface of the film, leaving it tack free. There are four important elements of proper drying: temperature, humidity, film thickness and airflow. Temperature affects viscosity, which contributes to film thickness. Humidity affects the evaporation rate of the solvents. The amount of airflow determines how much oxygen will crosslink with the finish to initiate curing. High temperatures, low humidity, thin film thickness and adequate airflow will all expedite dry time and cure time. If these elements are not maintained properly, the finish could dry too quickly.
Curing occurs when residual solvents leave the film and it begins crosslinking with oxygen in the air to develop strength, toughness, abrasion resistance and chemical resistance. Although most finishes reach 90% cure in seven days, full cure takes up to thirty days.