C33 Identifying and Remedying Paint Failures and Defects 2

Question 1

A newly painted exterior wall exhibits small, round craters exposing the substrate. What is the most likely cause of this defect?

Accepted Answer

Contamination by silicone or oil on the surface before painting

Answer

Cratering (fisheyes) is caused by surface contamination from silicone, oil, grease, or wax that repels the paint film, creating round depressions.

Question 2

What causes intercoat adhesion failure between primer and topcoat on a steel surface?

Accepted Answer

Applying topcoat before primer has fully cured or exceeding the recoat window

Answer

Intercoat adhesion failure occurs when the topcoat is applied before the primer cures sufficiently, or after the recoat window closes and the primer surface becomes too hard for mechanical bonding.

Question 3

A C-33 contractor notices white, powdery deposits forming on a freshly painted masonry wall. What is this defect called?

Accepted Answer

Efflorescence

Answer

Efflorescence is the migration of soluble salts from within masonry to the surface, where they crystallize as a white powdery deposit.

Question 4

What is saponification in the context of exterior paint failure on new concrete?

Accepted Answer

Chemical reaction between alkali in concrete and oil-based paint, breaking down the binder

Answer

Saponification is a chemical reaction where the high alkalinity of fresh concrete breaks down the oil or alkyd binder in paint, creating a sticky, soap-like film.

Question 5

A customer complains about visible brush marks in the dried paint on interior trim. Which factor most contributes to this defect?

Accepted Answer

Paint drying too quickly before it can level, often due to low humidity or excessive brushing

Answer

Brush marks remain visible when paint dries too quickly to self-level, often caused by hot/dry conditions, over-brushing, or insufficient paint on the brush.

C33 - C-33 California Painting Contractor License Practice Test

C33 - C-33 California Painting Contractor License Practice Test

C33 Identifying and Remedying Paint Failures and Defects 2