Most standard recommended recoat times are calculated based on an ambient temperature of 70° F. If the temperature of the substrate or the environment is lower than 70° F, you must allow for significantly additional cure time between coats. Applying the next coat too early in cool conditions will impede solvent evaporation and potentially compromise the final finish.
In addition to overall cure time, the flash time between coats plays a crucial role in preventing adhesion issues and surface defects, such as wrinkling. Flash time provides the necessary window for initial solvent evaporation, preparing the underlying surface for the next layer.
The application technique should be as follows:
- First Coat: The initial layer should always be applied lightly and must be allowed to flash properly. This lightly flashed coat acts like the sticky adhesive on tape, creating the ideal surface profile for the next layer to bond reliably.
- Second & third Coats: Once the first coat has flashed, the second coat can be applied at a medium to heavy thickness. Note that the required flash time before applying the third coat may even be longer than the flash time allowed for the initial coat.
If you do not allow the paint between coats to flash properly before applying the subsequent layer, the paint will not have enough time to evaporate all the solvents. When the topcoat is applied over this trapped solvent layer, it can prevent proper cross-linking and bonding. This solvent entrapment may cause the surface to wrinkle or lift as the entire coating system attempts to cure completely.
