Sagging

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).

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