
Sagging
When the paint gives a downward drooping appearance, the condition is referred to as Sagging. This results when a heavier coat of paint is sprayed on a vertical, or a near vertical surface than the viscosity of the finish.
Possible Causes |
Solutions |
Slow Over- Reduction of Solvent or by solvent that evaporates too quickly | Use solvents that are consistent with the general nature and temperature of the surface to be coated. |
Application of coat is too Heavy | • Control the coating applied to surface. • Apply thinner recommended coats and get a firm paint build. |
Presence of draft condition | Eliminate draft |
Presence of Strong Sunlight that causes top drying and consequently, late slipping of film on vertical surfaces | Avoid application in strong sunlight. |
Weather is cold and there is no circulation of air | Use faster evaporating, reducing thinner or bring room temperature upto 25° C. |
Dirty Air cap and Fluid tip | Remove cap and fluid tip and clean them thoroughly, before use. |
Spray Gun held Closer to the Surface | Hold the spray gun at a distance of 6-10 inches to the surface. |
Spray Gun Manipulated at Wrong Angle to the surface | Work spray gun at right angles to surface. |
Fluid Pressure too High | Reduce fluid pressure |
Failure to release trigger at end of stroke. Thus, stroke does not go beyond the object. | Release trigger after every stroke. |
Slow Spray Application | Speed up the movement of the spray gun across surface. |
A fatty edge | First, spray the edges with a thin coat. Then, spray the rest of the surface. |
Improper atomization | • Use larger air cap (Internal Mix). • Increase volume of air through horns (External Mix). |