21 Cured Finish Defects Practice Questions & Answers

1. 1. A bumper cover made of raw, unprimed plastic was refinished last month, and the paint is now peeling off in sheets down to the bare plastic. Painter A says the most likely cause is that no adhesion promoter was applied to the raw plastic. Painter B says the correct repair is to scuff the peeling edges and apply another coat of clear over the area. Who is right?

   • A.Neither A nor B
   • B.B only
   • C.Both A and B
   • D.A only✓ Answer

   Peeling down to bare plastic is delamination, and raw plastic needs an adhesion promoter (or an undercoat made for that plastic) for the coating to bond, so Painter A is right. Painter B is wrong because nothing can be cleared or sealed over a finish that is not adhering: all loose paint must be removed back to a sound, well-bonded edge, featheredged and refinished with the correct adhesion promoter and undercoat.

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2. 2. A hood was refinished in basecoat/clearcoat three months ago. The clear is now peeling off in flakes, but the basecoat under it is intact and still well bonded to the primer. What is the most likely cause?

   • A.The hood was washed with plain water before the clear had fully cured
   • B.The clear was buffed with a coarse pad that wore through to the base
   • C.The clear went on too wet, so its solvent softened and lifted the base
   • D.The basecoat sat past its maximum recoat time before the clear went on✓ Answer

   When clear peels cleanly off an intact basecoat, the bond failed at the base/clear interface. A basecoat has a maximum recoat window on its TDS; once that window passes, the clear can no longer bond to it unless the base is scuffed or a fresh coat of base is applied as the TDS directs. Lifting shows up while spraying, washing too early causes water spots, and a buff-through is a cut spot, not flaking clear.

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3. 3. A customer's quarter panel, refinished about a year ago, now shows many small three-legged, star-shaped cracks in the topcoat. The customer asks whether the panel can just be polished. What is the correct repair?

   • A.Seal over the cracked film with primer-sealer, then apply new topcoat
   • B.Sand off all the cracked film down to sound material, then refinish✓ Answer
   • C.Wet sand the surface until the cracks fade, then compound and polish
   • D.Fill the cracks with glazing putty, block sand, then apply new clear

   Crow's-foot cracking runs down through the film, so it cannot be polished out, sanded at the surface, filled or sealed over: the cracks telegraph back through any new coating. The only lasting cure is to remove the cracked film down to a sound layer (or to the substrate if the cracks go that deep) and refinish.

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4. 4. A painter is investigating line-checking and crow's-foot cracking on a recent refinish. All of these could cause this type of cracking EXCEPT:

   • A.Holding the gun too far away so the clear dried sandy✓ Answer
   • B.Mixing the clear with too much or too little hardener
   • C.Recoating before the previous coat had its full flash time
   • D.Applying far more total film build than the TDS allows

   Cracking comes from stress in the film: excessive film build, too little flash time between coats and an incorrect hardener ratio all leave a film that shrinks unevenly or becomes brittle and cracks with age and temperature cycling. Holding the gun too far away produces dry spray, a rough texture defect that forms during application, not cracking in the cured film.

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5. 5. A painter notices a run in a door's fresh clearcoat about 30 minutes after spraying. The clear is still soft. What is the best way to repair it?

   • A.Compound it now at high buffer speed so the heat flattens the run before it cures
   • B.Let it fully cure, then level it with a block or run file, wet sand, compound and polish✓ Answer
   • C.Wipe it with reducer to dissolve the run, then respray clear over the whole door
   • D.Sand it right away while the clear is still soft, since soft clear levels out faster

   Sanding an uncured run smears and tears the soft film instead of leveling it, and heat or solvent only makes the soft clear move further. The run must cure completely; it is then leveled with a sanding block or a dedicated run file, wet sanded progressively finer, compounded and polished. If leveling would cut through the clear, the area is re-cleared.

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6. 6. Small raised bubbles appeared in a refinished fender about a week after delivery. When one is cut open, it contains a trace of moisture. Painter A says water from an air transformer and filters that were not drained could be the cause. Painter B says sanding water left on the panel before priming could be the cause. Who is right?

   • A.B only
   • B.Neither A nor B
   • C.Both A and B✓ Answer
   • D.A only

   Moisture blisters form when water is trapped under the film and later expands or draws more moisture through it. An undrained air transformer or filter and sanding water not fully dried before priming both put water under the coating, so both painters name valid causes. Prevention is a clean, dry air supply and a thoroughly dried surface.

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7. 7. A hood shows blistering across a large area. Cutting into several blisters shows they go down through the topcoat to the primer, and moisture is found under them. What is the correct repair?

   • A.Pierce each blister, let the panel dry in the sun for a day, then apply new clear
   • B.Apply a bleeder-sealer over the blistered area to lock the moisture in, then topcoat
   • C.Remove the finish to sound material, fix the moisture source, dry the panel and refinish✓ Answer
   • D.Wet sand the blister tops flat, then compound and polish until the gloss comes back

   Blisters that reach the primer mean moisture is trapped under the whole film; sanding the tops, piercing them or sealing over them leaves the moisture and the weakened film in place, so the blisters return. The blistered finish is removed to sound material (often to the substrate), the moisture source such as an undrained air transformer is corrected, the surface is dried, and the panel is refinished.

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8. 8. Two days after a refinish, the customer washed the car in direct sun and let it air-dry. Ring-shaped spots remain after rewashing, and a fingernail can just feel slight etching in the clear, which has not been cut through. What is the correct correction?

   • A.Let the finish fully cure, then compound and polish the spotted areas✓ Answer
   • B.Wipe the spots with wax-and-grease remover to dissolve the mineral rings
   • C.Strip and refinish the panel, since any etching means the clear has failed
   • D.Apply a heavy coat of wax to fill the etched rings and hide the spots

   Water spots come from minerals left behind as water evaporates, and on a film that has not fully cured the water can etch slightly. Light etching that has not gone through the clear is corrected by compounding and polishing once the film has cured; stripping is reserved for severe etching, wax only hides the rings, and a solvent cleaner cannot remove an etch. The customer should not wash the car until the cure time on the TDS has passed and should dry it in the shade.

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9. 9. A bird dropping has dried on the hood of a car parked for several days in hot sun. Under the residue the clear looks dull and slightly etched, but it is not cut through. What is the correct way to correct it?

   • A.Leave the residue on and wax around it, since wax will neutralize the acid over time
   • B.Scrape the dried residue off with a razor blade, then wax over the dull mark to hide it
   • C.Soften the residue with warm water or cleaner, lift it off, then polish or compound the etch✓ Answer
   • D.Sand and refinish the whole hood right away, because acid etching always reaches the base

   Bird droppings are acidic and heat speeds up the etching. The residue should be softened and lifted gently rather than scraped, which would scratch the finish; an etch confined to the clear is then removed by polishing or compounding. Refinishing is needed only if the etch has penetrated the clear, and wax protects a clean finish but neither neutralizes residue nor repairs an etch.

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10. 10. A light-colored vehicle parked near a rail yard has tiny orange specks across its horizontal panels that feel rough to the touch. What is the correct correction sequence?

    • A.Wash, apply iron fallout remover, neutralize and rinse, clay the surface, then polish✓ Answer
    • B.Compound the specks with a wool pad at high speed until the orange color is gone
    • C.Wet sand each affected panel and re-clear, since fallout can't be removed otherwise
    • D.Wash, clay with heavy pressure to pull out the specks, then compound with a rotary

    Rail dust is hot iron particles that embed in the clear and rust. A chemical iron remover dissolves the particles; it is then neutralized and rinsed so the acid-based product cannot keep etching, and a clay bar lifts the remaining loosened contamination before polishing. Clay or compound alone drags embedded iron across the surface and scratches it; sanding and refinishing are needed only when the damage has penetrated the clear.

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11. 11. A vehicle has acid-rain marks and industrial fallout on its finish. Painter A says acid-rain etching that has gone through the clearcoat can be corrected by claying and polishing. Painter B says that after an acid-based fallout remover is used, the surface should be neutralized with a mild alkaline wash and rinsed. Who is right?

    • A.A only
    • B.Neither A nor B
    • C.Both A and B
    • D.B only✓ Answer

    Once etching penetrates the clear there is no clear left to level, so the area must be sanded and refinished; Painter A is wrong. Painter B is right: an acid-based decontamination product left on the surface can keep etching, so it is neutralized with a mild alkaline wash and rinsed before claying and polishing.

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12. 12. A customer's aged single-stage finish looks dull and leaves colored powder on a cloth when rubbed. The film is still intact, with no cracks. Which plan is correct?

    • A.Spray clear right over the chalky film so the gloss returns without color loss
    • B.Wash it with a strong degreaser, since chalking is only road film on the top
    • C.Wet sand the whole car and re-clear it, because chalk always means a failed clear
    • D.Compound off the chalked layer, polish it, then protect it with wax or sealant✓ Answer

    Chalking is UV and weather breakdown of the binder that leaves loose pigment on the surface. In a light case on an intact single-stage finish, compounding removes the oxidized layer, polishing restores gloss and wax or sealant protects it. A single-stage finish has no clearcoat to fail, and clear sprayed over chalk will not adhere, because chalk must be removed before any refinishing.

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13. 13. A panel originally painted dark red is refinished in white. A day later the new white has a pink tint across the whole panel. What is the most likely cause, and how should it have been prevented?

    • A.Red overspray drifted in from the next booth; mask the whole vehicle more fully
    • B.Red pigment bled into the topcoat; seal it with a bleeder-sealer before refinishing✓ Answer
    • C.The white was mixed with the wrong toner; check a spray-out panel before spraying
    • D.The white was sprayed too thin to hide; apply more coats until coverage is full

    A discoloration that matches the old color and covers the whole panel is bleed-through: soluble dyes in older reds and maroons dissolve in the new topcoat's solvents and migrate up into it. Testing the old finish with a white solvent-dampened rag reveals the risk, and a bleeder-sealer (isolator) blocks the migration. Overspray sits on top in a dusting pattern, and poor hiding shows the old color through thin spots rather than tinting the film.

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14. 14. A painter is checking an older finish and a body-filler repair before refinishing. Painter A says rubbing the old finish with a white rag dampened with solvent and checking for color transfer shows whether bleed-through is likely. Painter B says a yellow stain in the topcoat over a filler repair can come from too much hardener in polyester body filler. Who is right?

    • A.B only
    • B.Both A and B✓ Answer
    • C.Neither A nor B
    • D.A only

    Color that transfers to a white solvent-dampened rag shows the old finish contains soluble pigment that can bleed into a new topcoat, so a bleeder-sealer is needed. Excess peroxide hardener in polyester filler can also migrate into the topcoat and stain it, which is why filler hardener is measured to the manufacturer's directions. Both statements are correct.

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15. 15. While compounding a fender, a technician sees the color change along a sharp body line where the pad was held with pressure. The clear has been cut through to the basecoat there. What is the correct repair?

    • A.Re-clear the area, re-basing it first if the base was also cut✓ Answer
    • B.Touch up the line with a small brush of clear, then level and buff it out
    • C.Polish the line with a finer foam pad until the gloss blends into the clear
    • D.Apply a filler glaze along the line to rebuild depth, then wax the fender

    Burn-through removes the clear, and no polishing, glaze or brush touch-up replaces the film that protects the base from UV. The area must be refinished: re-cleared, with basecoat applied first if the color coat was also cut. It happens most on edges and body lines, so edges are taped off and the pad is kept flat and moving.

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16. 16. A painter applied clearcoat well above the maximum film build listed on the TDS. All of these are likely results EXCEPT:

    • A.Early failure from too little UV protection✓ Answer
    • B.Solvent popping as trapped solvent escapes
    • C.Die-back as the thick film keeps shrinking
    • D.Cracking as the heavy film becomes stressed

    Excess film build traps solvent and stresses the film, producing solvent popping, die-back, cracking, slow drying and wrinkling. Poor UV protection and early failure come from the opposite error, a clear applied too thin, which is why film build is checked with a mil gauge against the range on the TDS.

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17. 17. A painter finds dust nibs in a metallic basecoat before clearing and sands them out with fine paper. What should be done next?

    • A.Tack the area and apply an extra-heavy first coat of clear to level the scratches
    • B.Apply the clear directly, since the clear will fill and hide the sanding scratches
    • C.Compound and polish the sanded spots in the basecoat, then apply the clearcoat
    • D.Apply another coat of basecoat over the area so scratches and mottling are hidden✓ Answer

    Sanding a metallic basecoat disturbs the flake and leaves scratches that the clear magnifies rather than hides. Another coat of basecoat over the sanded area restores uniform flake orientation and color before the clear is applied. Basecoat is not compounded, and an extra-heavy first clear coat invites runs and solvent problems.

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18. 18. A clearcoat was force-dried with infrared lamps almost immediately after the final coat. After cooling, the panel shows many tiny craters and pinhole-like bumps in the clear. What is the most likely cause?

    • A.Silicone on the panel kept the clear from wetting out and pulled it into craters
    • B.Porosity in the body filler under the repair released air up through every coat
    • C.Solvent trapped under a skin forced its way out because the bake started too soon✓ Answer
    • D.Moisture from an undrained air line was sprayed into the clear and then expanded

    Baking before the coat has flashed lets the surface skin over while solvent is still inside; the solvent then bursts through the skin and leaves solvent pops. Fish-eyes from silicone appear while spraying, filler pinholes come from the undercoat, and moisture blisters are raised bubbles rather than open craters. Light pops are wet sanded and polished after cure; deep ones are sanded out and refinished.

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19. 19. After the topcoat cured, sand scratches from the prep work show through the new finish on a door. All of these help prevent this sand-scratch swelling EXCEPT:

    • A.Building enough undercoat film to fill and cover the scratches
    • B.Switching to a coarser grit so the topcoat gets more bite✓ Answer
    • C.Finish sanding with the grit the TDS specifies for the topcoat
    • D.Applying a sealer over the sanded area before the basecoat

    Sand-scratch swelling happens when topcoat solvents swell the edges of scratches that are too coarse or too thinly covered; the scratches then show after the film shrinks during cure. Finishing with the specified grit, sealing and building adequate film all prevent it, while a coarser grit cuts deeper scratches and makes it worse. Mapping, by contrast, is the outline of an uncured filler or featheredge repair showing through.

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20. 20. After a technician buffs a black hood, fine circular scratches (swirl marks) are visible in direct sunlight. Painter A says the swirls were caused by moving the buffer too slowly across the panel. Painter B says the swirls were caused by using a low-speed polisher. Who is right?

    • A.Both A and B
    • B.A only
    • C.Neither A nor B✓ Answer
    • D.B only

    Swirl marks are scratches left by a pad (or compound) that is too coarse or dirty for the finishing step, so neither statement identifies the cause. The cure is to step down to a finer pad and finishing polish, often with a dual-action polisher, until the scratches are gone. Trails left by a rotary buffer are called holograms.

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21. 21. A clearcoat looked glossy at delivery, but three weeks later it has gone dull and shows the texture of the surface underneath. Painter A says this is chalking caused by UV breaking down the binder. Painter B says excessive film build or buffing before the clear fully cured could cause it. Who is right?

    • A.B only✓ Answer
    • B.Neither A nor B
    • C.Both A and B
    • D.A only

    Gloss that dies days or weeks after a good-looking job is die-back: solvent keeps escaping, and the film shrinks and follows the texture beneath it. Excess film build, short flash times and buffing before full cure all contribute, so Painter B is right. Chalking is UV oxidation of an aged film and does not appear on a three-week-old finish. Die-back is corrected after full cure by compounding and polishing, or by sanding and re-clearing if it recurs.

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Practice questions based on the Official ASE Study Guide task list for the Painting and Refinishing (B2) test. This site is not affiliated with or endorsed by ASE, and these are not real exam questions. ASE revises its task lists periodically and sets the test length, passing standard and certification requirements, including the hands-on experience required for certification, which is separate from registering for the test. Mix ratios, flash and bake times, film builds and gun settings come from each product's own technical data sheet and are deliberately not tested here; VOC and emission rules are set federally and may be stricter in your state or air district. Confirm the current study guide and the rules that apply where you work. Official ASE B2 test page →