Painting Defects

Dirt Retention

This is the deposition of dirt and dust on the paint film. For certain types of paint, the dirt may become entrained into the surface. The paints that resist dirt retention are high-gloss enamels while the low gloss latexes are the most susceptible to this defect.

Fading

Fading is the decrease in the intensity of the color after exposure. It should be tested for after removal of any chalking that may have occurred as this will tend to mask the actual fade of the pigment. In general organic pigments, especially those of low cost, will fade more than pigments that are inorganic. More expensive coatings especially prepared for exterior exposure will resist fading more than less expensive paints.

Fish Eye

This defect is indicated by small round imperfections in the top coat. The defect is caused by traces of silicone or oil on the surface prior to painting. The remedy is to thoroughly clean the surface and if spray painting, to ensure that there is an oil filter on the air line.

Flaking

Flaking is the lifting of small-to-large sections of the paint and is due to poor adhesion and to the brittleness of the paint. The causes can be varied, for example the defect could be caused by efflorescence or the migration of soluble salts to the paint-media interface which can cause the paint to be forced off the surface. The paint may react with moisture and any traces of alkali to decompose the paint - this is called saponification. It may be due to failure to remove millscale from the steel before painting.

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