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Origin and Potential Causes:
· Solvent or air trapped in film escapes during drying leaving pop marks. · Incorrect spray viscosity, spray pressure, flash off time, or improper drying.
· Incorrect choice of hardeners and/or thinners. Use of fast-dry thinner or reducer, especially when the material is sprayed too dry or at excessive pressure.
· Excessive film thickness. Insufficient drying time between coats and too heavy application of the undercoats may trap solvents causing popping of the color coat as they later escape.
· Incorrect drying of primer / fillers.
· Improper surface cleaning or preparation.
· Infrared facilities too close.
· Baking was started too soon after application. · Baking temperature too high.
Prevention Techniques:
· Thoroughly clean all areas to be painted.
· Select the thinner or reducer that is suitable for existing shop conditions
· Don't pile on undercoats or topcoats. Allow sufficient flash and drying time. Allow each coat of primer- surfacer to flash off naturally - DO NOT FAN.
· Apply film at recommended thickness.
· Follow technical recommendations of products in use.
Remedy:
· If damage is extensive and severe, paint must be removed down to undercoat or metal, depending on depth of blisters; then refinish.
· In less severe cases, sand until smooth, resurface and refinish
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