Technical data

Table 4-1. Spray Coating Troubles, Possible Causes, and Remedies - Continued
Trouble Possible Causes Preventive Measures Or Remedies
Fish-Eyes and
Poor Wetting,
Crawling, Poor
Flowout. (Figure
4-20)
Use of waxes or sealants and adhesives
containing silicones. Presence of other
types of oils, greases, or hydraulic fluids
on the surface.
NOTE
Minute quantities of silicones can
cause this film.
Solvent clean with silicone-removing com-
pounds.
Lifting (Figure
4-21)
1. Absorption of solvents by previous par-
tially dried film.
1. Allow coats to dry/cure for the proper dry
to over-coat time before recoating for
epoxies, polyurethanes, and lacquers;
with enamels either allow first coats to
dry completely, or apply second coats
immediately.
2. Second coats apt to lift if surface is poorly
prepared.
2. Begin with properly prepared surface.
3. Use of lacquer over enamel. 3. Use compatible coatings and thinners.
Enamel may be applied over lacquer but
lacquer may not be applied over enamel.
4. Use of lacquer thinner in enamel. 4. Use compatible coatings and thinners.
Enamel may be applied over lacquer but
lacquer may not be applied over enamel.
Pitting or Cupping
(Figure 4-22)
1. Rust under surface. 1. Strip and clean; or sand down and repaint.
2. Oil or grease on surface. 2. Strip and clean; or sand down and repaint.
3. Moisture in lines. 3. Drain lines periodically.
4. Trapped solvents. 4. Use proper thinner proportions and allow
proper cure times.
TO 1-1-8
4-18