Runs & Sags

Description

Well defined local thickening of the paint film in the form of a wavy line or shallow, rounded ridges, normally confined to sharply sloping or vertical surfaces.

Cause

Slumping of the paint due to:

1. Excess thickness of application, air pressure too low, fan width too narrow, spray gun too close to the surface or moving too slowly.
2. Use of poor quality or incorrect thinner.
3. Incorrect viscosity of the paint.
4. Air of surface temperature too low.
5. Contamination of the underlying surface.

Prevention

1. Use the correct spraying technique and spray gun settings.
2. Use only recommended thinner.
3. Ensure that the paint is mixed to the correct viscosity.
4. Always spray within the recommended temperatures.
5. Ensure that the surface is scrupulously clean.

Rectification

Allow the paint to harden thoroughly, rub down excess paint, flat, compound and polish. In severe cases it may be necessary to rub down and repaint the surface.

NOTE: Due to separation of the metal flakes, metallic paints will normally require repainting.