Peaks and pits can be observed on the paint film due to non-controlled flows within the paint film after application on the surface, and during curing as the temperature in the oven increases untill the curing of the paint film is complete. This defect is often similar to orange peel, however, it is coarser looking when evaluated visually.
Peaks and pits appear during curing as the film viscosity decreases with the increasing oven temperature. The result is an uneven surface appearance, poor DOI (Distinctness of Image), and small spots in pits. The solution is using or optimizing the amounts of surfactants, thickening agents in the paint formula in order to reduce or eliminate surface tension gradients within the paint film. Using the combination of silicone based additives and thickeners, is often very effective. The use of silicone should be done carefully especially in oven-baking systems. (See Intercoat Adhesion Defect).