ASE Practice Test (B2: Painting & Refinishing) 2 — Questions and Answers
Question 1: A technician is preparing a repaired panel for painting. After sanding with 180-grit sandpaper, which action is required before applying primer?
- Apply a guide coat directly over the 180-grit scratches
- Clean the surface with wax and grease remover then apply a sealer or etching primer (Correct answer)
- Apply basecoat immediately to save time
- Sand with 400-grit dry paper only
Correct answer: Clean the surface with wax and grease remover then apply a sealer or etching primer
180-grit sandpaper leaves scratches that are too coarse for topcoat adhesion. The surface must be cleaned with a wax and grease remover to eliminate silicone and contaminants that cause fish-eye. An etching primer or sealer is then applied to fill scratches, promote adhesion, and provide a uniform foundation before applying primer-surfacer or topcoat.
Question 2: When mixing a two-stage (basecoat/clearcoat) system, the painter notices the clearcoat is too thick. What is the MOST likely result if it is applied at this viscosity?
- Better gloss and hardness due to more material
- Runs, sags, solvent pop, and poor atomization (Correct answer)
- Faster drying time with less orange peel
- Improved UV protection of the basecoat
Correct answer: Runs, sags, solvent pop, and poor atomization
Clearcoat that is too thick (high viscosity) will not atomize properly from the spray gun. The result is poor flow-out, runs, sags, and trapped solvents that cause solvent pop (small bubbles or craters). Material must be reduced according to the manufacturer's mix ratio and viscosity specifications, adjusted for temperature and humidity conditions.
Question 3: Which type of paint defect appears as a wrinkled or shriveled surface texture after applying a new coat of paint?
- Fish-eye
- Lifting (Correct answer)
- Solvent pop
- Dry spray
Correct answer: Lifting
Lifting occurs when the solvents in the new paint coat attack and swell the existing finish below it. This causes the old paint layers to wrinkle or shrivel. It commonly happens when applying lacquer or enamel over an incompatible previous finish, or when applying a strong-solvent product over an uncured previous coat. Proper sealing and finish compatibility prevent lifting.
Question 4: What is the purpose of a guide coat when block sanding a primer-surfacer?
- It adds color to the primer for better UV resistance
- It reveals low spots and high spots so the technician knows when the surface is flat (Correct answer)
- It promotes adhesion of the topcoat to the primer
- It prevents the sandpaper from loading up with material
Correct answer: It reveals low spots and high spots so the technician knows when the surface is flat
A guide coat is a thin, contrasting-color spray (or dry powder) applied over primer before block sanding. As sanding progresses, the guide coat is removed from high spots first while remaining in low spots. Any area where guide coat remains after sanding indicates a low spot that requires additional filler or primer. When the guide coat is fully and evenly removed, the surface is flat.
Question 5: A painter sprays metallic basecoat and notices the flakes appear dark and "mottled" in the center of the panel. What is the MOST likely cause?
- Too much air pressure at the gun
- The gun was held too close or moved too slowly, causing heavy wet coats (Correct answer)
- Insufficient reducer in the basecoat mix
- The clearcoat was applied too soon after basecoat
Correct answer: The gun was held too close or moved too slowly, causing heavy wet coats
Metallic flakes in basecoat orient parallel to the surface for maximum sparkle when applied in thin, even passes at the correct distance. Holding the gun too close or moving too slowly deposits too much wet material. The heavy wet coat causes the flakes to orient randomly and sink or cluster, creating dark, mottled areas. Correct gun distance and pass speed are critical with metallics.
Question 6: Which personal protective equipment (PPE) is MANDATORY when spraying isocyanate-containing two-component (2K) clearcoat?
- Safety glasses and latex gloves only
- A supplied-air respirator (SAR) or PAPR with appropriate cartridges (Correct answer)
- A dust mask and face shield
- Chemical goggles only
Correct answer: A supplied-air respirator (SAR) or PAPR with appropriate cartridges
Isocyanates in 2K clearcoat and hardeners are severe respiratory sensitizers. Once sensitized, even tiny exposures can trigger asthmatic reactions. NIOSH mandates a supplied-air respirator (SAR) or a properly fitted air-purifying respirator with OV/P100 cartridges specifically rated for isocyanates. A dust mask offers no protection against isocyanate vapors.
ASE Practice Test (B2: Painting & Refinishing) 2
A technician is preparing a repaired panel for painting.
After sanding with 180-grit sandpaper, which action is required before applying primer?