Painting & Refinishing Flashcards

Wrinkling (lifting) of a topcoat over old paint is typically caused by what?

Answer: Strong solvents attacking an uncured or incompatible underlying film

Aggressive solvents can penetrate and swell an incompatible or under-cured undercoat, causing it to wrinkle.

What grit sandpaper range is commonly used to wet-sand a clearcoat before buffing?

Answer: 1500 to 3000 grit

Very fine 1500–3000 grit removes minor defects while leaving scratches fine enough to buff out.

Runs and sags in a vertical panel are most often caused by:

Answer: Applying too much material or holding the gun too close

Excessive film build or a gun held too close lets gravity pull the wet paint downward into runs.

Why must adjacent panels and trim be properly masked before spraying?

Answer: To protect them from overspray and produce clean edges

Masking shields surrounding areas from overspray and defines crisp paint boundaries.

Dieback (loss of gloss after the paint dries) is usually due to:

Answer: Insufficient flash time between coats trapping solvent

Trapped solvent from inadequate flash continues to escape and dulls the gloss as it settles.

What is the correct general spray gun overlap for even coverage?

Answer: Roughly 50% overlap of each pass

Overlapping each pass about 50% delivers a uniform, even film without stripes.

Which respiratory protection is required when spraying isocyanate-containing 2K paints?

Answer: A supplied-air respirator or properly fitted air-purifying respirator

Isocyanates are hazardous, so a supplied-air or properly rated respirator is required.