Appendix A
From SAE J1800 APR87 "Method for Evaluating the Paintable Characteristics of Automotive Sealers", section 9, Appendix - Glossary of Terms.
In addition to the adhesive characteristics of a paint film, there are a large number of undesirable conditions that may arise due to a paint-sealer incompatibility. The following is a partial list of these undesirable conditions and the tester should take note of these in general and any others specifically requested.
Alligatoring
—A uniform distribution of surface cracking
in a symmetrical pattern resembling the skin of an alligator.
Black Lining
—Dark lines that appear along the tops of ridges
in the sealer due to paint flowing down the sides of the ridges.
Blistering
—Raised areas on the paint’s surface due to volatile
substances coming out of the sealer after the topcoat has started
to "cure."
Blushing
—A lightening of the paint’s hue due to moisture in
the air, moisture in the sealer, or poor hiding power of the topcoat.
Cracking
—Separations in the topcoat film before or after baking.
Cracking can be caused by shrinkage of the paint film during the
bake cycle, swelling of the sealer after the topcoat has started
to cure, or sliding of the uncured paint film on the uncured sealer
due to incompatibility.
Cratering
—Round depressions in the paint’s surface, usually
due to contaminants in the paint or on the surface being painted.
Discoloring
—A change in the absolute color of the topcoat usually
due to a chemical interaction between the topcoat and the sealer.
D.O.I.
—Distinctness of Image.
Dulling
—A reduction in the level of gloss, or D.O.I., of the
topcoat, usually due to an interaction between the topcoat and the
sealer beneath.
Fish Eyes
—Circular areas devoid of topcoat caused by the wet
paint "drawing" in on itself due to surface contaminants
such as oil or silicones or a general incompatibility of paint and
sealer.
Metal Flake Re-Orientation
—A uniform change, over the sealer,
in the apparent color of a metallic topcoat. This difference is
independent of the configuration of the sealer bead. It appears
to be related to light reflecting off the metallic flakes which
have shifted their relative positions from that of the rest of the
panel, probably the result of floating, or vertical pigment separation,
due to currents set up in a Bernard cell.
Metal Flake Mottling
—A puddling of the metallic and non-metallic
pigments in a topcoat giving it a blotchy appearance.
Pinholing
—Small holes, the size of a pinpoint, in the surface
of the topcoat that result when small bubbles burst as the paint
cures.
Popping
—Usually refers to a fairly uniform distribution of small
blisters caused by the volatilization of entrapped solvent beneath
a topcoat that has started to cure. The volatile material can be
from the sealer coated or from a layer of paint that is excessively
thick.
Running
—A movement or flowing of wet topcoat over the sealer
caused by a paint-sealer incompatibility or an excessive application
of topcoat.
Seedy Appearance
—A paint-sealer incompatibility causing pigment
(our intended readers won't know this one) beading to a surface
that is spotted with raised "grainy" looking particles.
Soft Paint
—A paint film that has not achieved its specified
hardness. This can be caused by the migration of plasticizers, into
the topcoat, from the sealer, or by the sealer chemically retarding
the topcoat’s curing system.
Staining
—A discoloring of the topcoat due to a sealer-topcoat
interaction.
Tacky Topcoat
—A more severe form of a "soft paint"
in which the sealer has interfered with the topcoat curing mechanism
to the degree that fingerprints can be left on the paint’s surface.
Yellowing
—A particular form of staining, in which a yellowish
stain appears, usually-associated with light color topcoats.
Wrinkling
—A paint-sealer incompatibility which causes the topcoat’s
surface to cure at a different rate resulting in the formation of
ridges. These ridges can vary in absolute size but generally are
uniform in size on any one particular panel.
Last Web Page Update 12/02/04