Technical data

Table 4-1. Spray Coating Troubles, Possible Causes, and Remedies
Trouble Possible Causes Preventive Measures Or Remedies
Sags and Runs 1. Dirty air cap and fluid tip (distorted spray
pattern).
1. Remove air cap and clean tip and air cap
carefully.
2. Gun stroked too close to the surface. 2. Maintain 6 to 10 inches for HVLP gun
distance from surface.
3. Trigger not released at end of stroke (when
stroke does not go beyond object).
3. Release the trigger after every stroke.
4. Gun stroked at wrong angle to surface. 4. Keep gun at right angle (perpendicular) to
surface during stroke.
5. Coating material too cold. 5. Heat material by approved methods.
6. Coating applied on too heavily. 6. Develop ability to apply correct thick-
nesses by panel practice.
7. Coating material thinned excessively. 7. Add the correct amount of solvent by
measure or determine by viscosity test.
Streaks 1. Dirty air cap and fluid tip (distorted spray
pattern).
1. Remove air cap and clean tip and air cap
carefully.
2. Insufficient or incorrect overlapping of
strokes.
2. Follow the previous stroke accurately. De-
posit a wet coat.
3. Gun stroked too rapidly (dusting of the
paint).
3. Avoid whipping. Make deliberate, slow
strokes.
4. Gun stroked at wrong angle to surface. 4. Keep gun at right angle (perpendicular) to
surface during stroke.
5. Stroking too far from surface. 5. Maintain 6 to 10 inches for HVLP gun
from surface.
6. Too much air pressure. 6. Use least air pressure necessary.
7. Split spray. 7. Clean the fluid tip and air cap.
8. Coating material too cold. 8. Heat material to get good flow-out.
Figure 4-13. Gun Sputters Constantly
TO 1-1-8
Change 2 4-13