Dirt

Description

A rough, irregular surface to the paint film is easily felt with the hand. The particles are often totally embedded in, and covered by the film.

Cause

Contaminating particles incorporated in the paint.

These may be the result of:

1. Dust, dirt or threads falling from cloth or clothing or blown out of mouldings or panel joints during spraying, setting on the wet paint film.
2. Dust not properly removed from the surface prior to spraying.
3. Airborne particles setting on and becoming incorporated in the paint film during or immediately after spraying.
4. Dirt in the paint or thinners resulting from open or rusty cans.

Prevention

1. Ensure that cloths and clothing are clean and dust free, blow out mouldings and panel joints prior to spraying.
2. Clean down and tack-off the surface prior to spraying each coat.
3. Keep the spray shop clean and dust free, avoid sanding operations in the area of the spray booth. Wet down surrounding surfaces if necessary, ensure that the filtration system is working properly.
4. Keep all materials in clean, sealed containers and strain before use.

Rectification

Allow the paint to harden completely. Light surface dirt may be removed by flatting, compounding and polishing. Deep embedded dirt, or dirt in synthetic paints, requires the surface to be rubbed down until smooth and repainted.