Reason: Heat. Solvent entrapment usually occurs when excessive heat causes the sealer application to “skin” over the top and the remaining solvent to flash off underneath, causing bubbles. Solution: Applying sealer in the cool of the morning during the hot summer months will prevent most solvent entrapment. However, if this occurs, apply an additional coat of sealer. This causes the sealer to re-emulsify and allow the solvent to escape.