7.4 Types of Failures

(E) Runs or Sags 

Identification:

These are also called curtains which is an appropriate term. Downward movement of the film between the time of application and setting results in an uneven coating having a thicker lower edge.

Description:

Too much paint has been applied on the surface and the surface is too hard to hold the paint.

Remedy:

• Flat down the clear coat

• Flat down the base coat

• Re-apply a thin base coat

• After cure, sand blast and apply another coat. 

• Choose an appropriate spray tip size to match the material being sprayed. 

(F) Orange Peel

Identification:

The coating dries to a finish that resembles the skin of an orange. 

Description:

Application of thick coatings prevents them from fully flowing out. It is caused by poor spraying technique such as holding the spray gun too close to the work. It may also be caused by low air pressure resulting in poor atomization.

Remedy:

• Flat down the surface and re-spray.