CAADE Repair and Refinishing Processes 5 — Questions and Answers
Question 1: A 'dry spray' finish defect is characterized by:
- Runs and sags in the paint film
- A rough, dull, or sandy texture caused by paint partially drying before reaching the surface (Correct answer)
- Lifting of the old paint caused by strong solvents
- Cloudy or milky appearance in the clearcoat
Correct answer: A rough, dull, or sandy texture caused by paint partially drying before reaching the surface
Dry spray occurs when atomized paint droplets partially evaporate in the air before landing, creating a rough, under-wetted surface texture.
Question 2: Resistance spot welding (RSW) on OEM-style repairs is preferred by manufacturers primarily because:
- It is faster than all other welding methods
- It closely replicates factory assembly welds and preserves the designed structural properties (Correct answer)
- It requires no special training or equipment
- It can be performed on any metal thickness without adjustment
Correct answer: It closely replicates factory assembly welds and preserves the designed structural properties
Factory-style resistance spot welding replicates OEM joining methods, maintaining the engineered strength and deformation characteristics of the vehicle.
Question 3: Which condition would most likely cause solvent popping defects in a refinished panel?
- Using too slow a reducer for ambient temperature
- Applying the clearcoat before the basecoat has properly flashed off (Correct answer)
- Applying too thin a primer coat
- Using a high-volume, low-pressure (HVLP) spray gun
Correct answer: Applying the clearcoat before the basecoat has properly flashed off
If clearcoat is applied before the basecoat has fully flashed, trapped solvents boil up through the clearcoat as it cures, creating small craters.
Question 4: When estimating refinishing for a three-stage (tri-coat) pearl finish, the estimator should account for:
- Standard two-stage refinish labor time
- Additional time for the midcoat pearl layer and increased blending complexity (Correct answer)
- A reduction in time because pearls apply faster than metallics
- No difference from a standard basecoat/clearcoat system
Correct answer: Additional time for the midcoat pearl layer and increased blending complexity
Tri-coat systems have a separate pearl midcoat that must be applied and blended, significantly increasing labor and blending difficulty.
Question 5: The purpose of an adhesion promoter applied before painting a TPO (thermoplastic polyolefin) bumper is to:
- Fill in surface porosity in the plastic
- Chemically bond to the non-polar plastic surface so that subsequent paint layers adhere properly (Correct answer)
- Provide a UV barrier for the plastic substrate
- Replace the need for sanding the bumper surface
Correct answer: Chemically bond to the non-polar plastic surface so that subsequent paint layers adhere properly
TPO is a non-polar plastic that paint does not bond to naturally; adhesion promoter modifies the surface energy to allow proper paint adhesion.
Question 6: A repair estimate that includes 'sectioning a quarter panel' rather than 'replacing a full quarter panel' should be justified when:
- The damage is extensive and affects the roof rail and C-pillar
- Only the lower portion is damaged and the OEM procedure permits sectioning at a specified location (Correct answer)
- The customer wants the cheapest possible repair
- The replacement panel is unavailable from any supplier
Correct answer: Only the lower portion is damaged and the OEM procedure permits sectioning at a specified location
Sectioning is appropriate when damage is limited and OEM guidelines permit it, reducing repair cost while maintaining structural integrity.
Question 7: After final color sanding a clearcoat to remove texture, the compound and polish sequence is used to:
- Remove the remaining sealer residue from the surface
- Restore gloss by progressively eliminating the fine scratches left by the sandpaper (Correct answer)
- Apply a protective wax layer to the new finish
- Re-activate the clearcoat for a second cure cycle
Correct answer: Restore gloss by progressively eliminating the fine scratches left by the sandpaper
Compounding removes the coarser sanding scratches, while polishing removes compound marks, restoring a high-gloss, optically clear finish.
CAADE Repair and Refinishing Processes 5
A 'dry spray' finish defect is characterized by: