What Causes Spray Paint to Wrinkle?by Timothy Burns
A perfect sprayed-on paint finish is the result of careful preparation, thin coats of paint and patience. If any of the steps are hurried or if drying time recommendations are not followed, the expected glassy smooth paint surface likely will devolve into a marred, blotchy or wrinkled mess. If this occurs, the paint must be removed, the object prepared again and the surface repainted correctly.
Heavy Single Coat
The advantage of spray paint is the speed at which the paint is applied. The painter doesn't have to worry about paint brushes, messy solvents and open cans that can accidentally tip. With the convenience of spray paint can come an expectation that the paint can be applied in one heavy coat. This assumption is incorrect. Spray paint should be applied in multiple thin coats, each of which is allowed to dry completely before applying additional coats. If spray paint is applied in a single heavy coat, the weight of the paint may be too great and the paint will wrinkle or sag as it dries.
Inadequate Dry Time
If a first coat of spray paint is not allowed to dry adequately before the second coat is applied, the solvents and drying agents in the second coat of paint can compromise the hard shell of the first coat, converting it into a slimy, unstable surface. As a result, the second coat attempts to bond to an unstable substrate. In this case, the topcoat wrinkles because it loses adhesion to the item's surface.
Another reason behind wrinkled sprayed-on paint is surface contamination. For spray paint to dry properly, it must have a clean, dry and properly prepared surface. If the surface is contaminated with a solvent or cleaner film left from the surface preparation steps, that residue can react with the spray paint carriers and cause the spray paint to wrinkle as it dries. In this case, the paint must be removed and the surface re-cleaned before being repainted.
Paint formulations vary from one paint line to another. Some use acrylic- or water-based carriers. Other paints are lacquer-based, and some are propelled by volatile epoxy solvents. These products are not compatible. If a lacquer-based finish coat is applied over a standard, fast-drying product, the lacquer carriers and driers likely will dissolve the first coat, creating a wrinkled finish. When painting any item, make sure the primers, base coats and top coats are designed to work together.