ASE Practice Test (B3: Non-Structural Analysis & Damage Repair) 3 — Questions and Answers
Question 1: Before applying polyester body filler, what is the MOST important surface preparation step?
- Apply a coat of primer first to improve adhesion
- Sand the bare metal to 80-grit to create a clean anchor pattern and remove rust/oxidation (Correct answer)
- Heat the panel with a heat gun to open the metal pores
- Apply a conversion coating only
Correct answer: Sand the bare metal to 80-grit to create a clean anchor pattern and remove rust/oxidation
Polyester body filler must be applied directly to bare, clean, sanded metal. It should never be applied over paint, primer, or rust. Sanding to 80-grit creates a mechanical anchor pattern for the filler to bond to. Any rust or oxidation under the filler will cause adhesion failure and bubbling. The metal must also be clean and free of wax, grease, and moisture.
Question 2: Which type of plastic is identified by the recycling code "PP" and requires what type of repair adhesive?
- Polycarbonate — requires epoxy adhesive
- Polypropylene — requires a hot-melt or urethane adhesive specifically formulated for low-energy plastics (Correct answer)
- Polyurethane — requires two-part structural adhesive
- ABS plastic — requires cyanoacrylate (super glue)
Correct answer: Polypropylene — requires a hot-melt or urethane adhesive specifically formulated for low-energy plastics
Polypropylene (PP) is a low surface energy (LSE) plastic used for bumper covers. Its smooth molecular surface resists adhesion, requiring adhesives specifically formulated for LSE plastics (often urethane or modified acrylics). Standard adhesives will not bond properly. PP parts also require adhesion promoter before painting. Misidentifying plastic type leads to adhesive failure.
Question 3: A quarter panel being replaced requires cutting through the original factory spot welds. Which tool is the BEST choice to remove the welds without damaging the inner panel?
- Standard twist drill bit
- Spot weld cutter (hole saw type) set to drill through only the outer layer (Correct answer)
- Angle grinder with a grinding disc
- Air chisel with a flat chisel bit
Correct answer: Spot weld cutter (hole saw type) set to drill through only the outer layer
A spot weld cutter (also called a spot weld drill or panel cutter) is a specialized hole saw designed to cut through only the outer panel layer at the weld nugget without drilling into the inner reinforcement panel. This preserves the integrity of the inner structure. Standard drill bits and grinders often damage the inner panel, requiring additional repair or section replacement.
Question 4: When applying polyester body filler, what does using too much hardener (cream hardener) cause?
- Filler will not cure at all
- Filler cures too fast, pinholes are more likely, and the filler becomes very hard and difficult to sand (Correct answer)
- Filler shrinks less and adheres better to metal
- Filler becomes flexible and waterproof
Correct answer: Filler cures too fast, pinholes are more likely, and the filler becomes very hard and difficult to sand
Polyester body filler must be mixed at the ratio specified by the manufacturer (typically about 2% hardener by volume). Too much hardener causes excessively fast curing that generates excess heat, which can cause pinholes (small gas bubbles from rapid off-gassing), brittleness, and poor adhesion. Over-catalyzed filler is also very hard and difficult to sand without loading the paper.
Question 5: What causes "featheredging" in a repair area, and why is it done?
- Featheredging adds texture to the substrate for filler adhesion
- Featheredging tapers the edges of existing paint layers to a thin, gradual slope so new materials can be applied without visible edge buildup (Correct answer)
- Featheredging removes clearcoat only from the repair area
- Featheredging is done only when applying body filler over primer
Correct answer: Featheredging tapers the edges of existing paint layers to a thin, gradual slope so new materials can be applied without visible edge buildup
Featheredging is the process of sanding the edges of existing paint layers so they taper smoothly and gradually into the bare metal rather than ending abruptly. Without featheredging, the sharp edge of old paint layers would telegraph through the new finish as a visible ridge. Proper featheredging ensures a smooth, invisible blend between repaired and original surfaces.
Question 6: A technician finds that body filler has developed pinholes after sanding. What is the correct repair procedure?
- Apply additional filler over the pinholes and sand again
- Apply glazing putty (finishing putty) designed to fill pinholes, then sand smooth (Correct answer)
- Seal the pinholes with clearcoat before priming
- Sand deeper to remove all filler and start over with new filler
Correct answer: Apply glazing putty (finishing putty) designed to fill pinholes, then sand smooth
Pinholes in body filler are small voids caused by air entrapment during mixing or application. Reapplying polyester filler over pinholes typically introduces more air and more pinholes. Glazing putty (a fine-grain finishing putty) is specifically formulated with low viscosity to fill small pinholes, scratches, and imperfections before priming. It should be applied thinly and sanded with fine-grit paper.
ASE Practice Test (B3: Non-Structural Analysis & Damage Repair) 3
Before applying polyester body filler, what is the MOST important surface preparation step?