Paint Runs problems

This section includes Paint Runs problems curtains and sags in Automotive paint.
To repair if sag is still wet, and another coat can be applied, lightly brush out the sag with a fine camel hair brush, then recoat. When colour coat is completely dry and
hard, flat out sag with P600 grit wet and dry. Polish out or respray as necessary. Spraying should never be done without plenty Of Properly located light. Many runs are the result of not being able to see the area being sprayed.

Cause

• Spraying over surface contaminated with wax, oil, grease or silicone.
• Use of too much slow-drying thinner.
• Coats applied too heavy and wet.
• Poor spray gun technique or adjustment.
• Distorted spray pattern.
• Material, surface or atmosphere too cold.
• Air pressure excessively low.

Prevention
1.  Clean surface thoroughly with wax and grease remover before painting.
2.  Avoid use of thinner which is too slow drying. Follow paint manufacturer's instructions as to type and amount of thinner.
3.  Do not apply heavy coats. Rely on thin to medium coats.
4.  Clean and adjust spray gun to give proper, uniform spray pattern. Develop and practice good spray gun technique.
5.  Use good triggering action. Curved surfaces require extra careful gun action.
6.  Since different brands of paint and thinner require somewhat different techniques
7.  practice on old panel when switching to new materials to obtain the 'feel' of the material.
8.  Adjust air pressure and spray gun settings and technique to compensate for temperature and weather conditions.
9.  Be sure spray booth allows plenty of room for easy working in uncramped position.