C33 Identifying and Remedying Paint Failures and Defects 4 — Questions and Answers
Question 1: A painted wood surface shows a condition where the paint film has split along the wood grain lines. What is this defect called?
- Checking (Correct answer)
- Alligatoring
- Crazing
- Intercoat peeling
Correct answer: Checking
Checking is the splitting of the paint film along or across wood grain, typically caused by overly thick paint or inadequate flexibility of the coating.
Question 2: Which condition describes a paint failure where new paint peels away from the previous coat but both remain bonded to the substrate?
- Substrate peeling
- Intercoat adhesion failure (Correct answer)
- Chalking
- Burnishing
Correct answer: Intercoat adhesion failure
Intercoat adhesion failure occurs when insufficient surface preparation, incompatible products, or insufficient dry time causes the new coat to separate from the previous coat.
Question 3: A homeowner notices a dark, fuzzy growth appearing through a freshly painted bathroom wall. What is the most likely cause?
- Efflorescence bleeding through the paint
- Mold or mildew growth from moisture not fully remediated before painting (Correct answer)
- Tannin bleed from wood substrate
- Iron oxide staining from fasteners
Correct answer: Mold or mildew growth from moisture not fully remediated before painting
Painting over active or inadequately treated mold without proper remediation allows growth to continue and penetrate through the new paint film.
Question 4: When painting over a glossy surface without sanding or etching, which failure mode is most likely to occur?
- Sagging
- Poor adhesion leading to peeling (Correct answer)
- Wrinkling
- Grinning
Correct answer: Poor adhesion leading to peeling
Glossy surfaces offer insufficient mechanical or chemical bonding sites, so the new coat fails to adhere and eventually peels.
Question 5: What paint defect results from applying a solvent-based topcoat over a water-based primer that has not fully cured?
- Flashing
- Lifting or wrinkling of the topcoat (Correct answer)
- Pinholing
- Sagging
Correct answer: Lifting or wrinkling of the topcoat
The solvents in the topcoat soften the uncured primer beneath, causing the topcoat to wrinkle or lift as trapped solvents escape.
Question 6: A painter observes that a recently applied exterior coat has a dull, hazy appearance in certain areas compared to the rest of the wall. This is called:
- Flashing (Correct answer)
- Chalking
- Burnishing
- Blooming
Correct answer: Flashing
Flashing is an uneven sheen caused by differences in porosity, application technique, or touch-up painting over a dried coat without feathering properly.
Question 7: Which of the following is the correct remediation sequence for a surface exhibiting heavy alligatoring?
- Apply a bonding primer directly over the existing pattern and repaint
- Remove all failing paint, treat the substrate, prime, and repaint (Correct answer)
- Sand lightly and apply a flexible elastomeric coating immediately
- Wet-scrape the surface and apply two topcoats without primer
Correct answer: Remove all failing paint, treat the substrate, prime, and repaint
Alligatoring indicates a fundamentally failed paint system; complete removal to bare substrate, proper prep, priming, and repainting is the only reliable long-term fix.
C33 Identifying and Remedying Paint Failures and Defects 4
A painted wood surface shows a condition where the paint film has split along the wood grain lines.
What is this defect called?