- Improper preparation of surface.
- Wrong undercoats.
- Thoroughly clean the old finish with
Prep-Sol to remove grease, wax, polish, and other foreign matter. Improper
treatment of bare metal surfaces also causes poor adhesion.
- Follow “Procedures” and label
Chalking of lacquers
The left section of this panel, which was
exposed on a paint farm, shows (in comparison with an unexposed section
on right) what happens when a finish chalks. A natural failure, chalking
is the gradual breaking up of the film under weathering and exposure to
the sun’s rays. It results in a gradual loss of gloss and powdering of
When this condition is encountered, rub
and polish the surface to remove “dead” pigments and get to
the “live” film beneath. Then wax the finish to protect and
prolong its life.
The use of a mist
coat mixed with a slower-drying thinner on a finishing job will enable
the film to set better and aid in retarding chalking.
Rough, dirty finish
- Applying finish over dusty surface.
- Dirty and dusty shop or spray booth conditions.
- “Tack-wipe” the surface immediately
before spraying color coats in order to remove dust and dirt. Tack rags
were a regular part of finishing equipment in the old days when varnish
was used. Now with synthetics it’s a habit to be cultivated again. Get
in the tack rag habit. They cost little—and save a lot of headaches.
- Good housekeeping.
This condition results from applying lacquer
type products over unaged air dry synthetic finishes. It also results
from applying a finish over a surface from which old wax, grease, or polish
is not thoroughly removed. To avoid the latter, always clean the old surface
with Prep-Sol to remove wax, grease, polish, and other foreign matter
before any sanding is done. Improper recoat time may also cause lifting.
Shrinking and splitting of putty
Because putties usually dry quickly, they
may shrink, split, and remain soft when applied too heavily, as shown
by this close-up.
Apply several light coats with a glazing
knife or squeegee, allow to dry between coats.
If you apply finish over a waxed surface
you encounter a difficulty as illustrated on the panel shown here—in
this case wet spots which spoil the job. To avoid this, use Prep-Sol as
a cleaning agent to remove wax, grease, and polish from the old surface.
Crazing, cracking, and checking
These conditions, each a degree of the other,
- Topcoats are applied before the undercoats
- Too heavy coats are applied, resulting
in non-uniform drying throughout film.
- New finish is applied over excessively
built-up, aged. and cracked old finish.
- Always let undercoats dry thoroughly
before spraying color coats. Weather conditions will alter drying time—so
do not follow a standard time.
- Do not “pile” on coats.
- If old finish is made up of an excessive
number of coats and/or if cracking of the old finish is in evidence,
remove the old finish completely before refinishing.