Click on the below images for a magnified view of additional examples:

Salt Blister, Top View (8x)	Salt Blister, Top View (42x)

• Residue of sanding water in corners, edges, crevices, or below decorative strips.
• Ambient humidity too high.
• Improper surface cleaning or preparation. Tiny specs of dirt left on the surface can act as a sponge and hold mosture. When the finish is exposed to the sun (or abrupt changes in atmospheric pressure), moisture expands and pressure builds up. If the pressure is great enough, blisters form.
• Wrong thinner or reducer. Use of a fast-dry thinner or reducer, especially when the material is sprayed too dry or at an excessive pressure. Air or moisture can be trapped in the film.
• Excessive film thickness. Insufficient drying time between coats or too heavy application of the undercoats may trap solvents which escape later and blister the color coat.
• Contamination of compressed air lines. Oil, water or dirt in lines.
• When wet sanding polyester and applying topcoat without enough time for the water to evaporate.
• Incompatibility of materials.

• Always remove exterior trim.
• Blow and dry carefully.
• Thoroughly clean areas to be painted before sanding. Be sure surface is completely dry before applying either undercoats or topcoats. Don't touch a cleaned area as the oils in your hands will contaminate the surface.
• Select the thinner or reducer most suitable for existing shop conditions.
• Allow proper drying time for undercoats and topcoats. Be sure to let each coat flash before applying the next.
• Drain and clean air pressure regulator daily to remove trapped moisture and dirt. Air compressor tank should also be drained daily.
• Clean substrate carefully.