Depressions as small as pin holes or pores of the leather, appear from the top to the bottom of coatings.
Common Cause
Pinholes are mainly caused by solvent or moisture, gathering underneath the top layer, no way to volatilize. (1) Excessive paint film thickness and no enough time for drying.
Air trapped in putty and become pinholes after sanding.
Bad choice of thinner, such as wrong ratio, bad quality, or incorrect type of dry time.
Incorrect initial cleaning or other pre-treatment, lead moisture existing and bringing about pinholes in the process of evaporation.
Unsuitable spray techniques, such as incorrect spray gun adjustment or too short distance to the working substrate.
Insufficient flash-off time before force drying, sudden heating-up, too fast exterior drying.
Too high temperature of the repair substrate itself.
Repair
(1) Sand through to putty layer, fill pinholes and redo putty works where needed, then sand smooth and continue the repair process.
(2) Pinholes or scratches in the putty surface after sanding can be filled by a thin coat of polyester putty or pinhole filler. Hold the spreader vertical to the surface so that the spreader may push the putty into the holes and does not pull it out at each stroke.
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