20 Primers, Fillers & Masking Practice Questions & Answers

Every Primers, Fillers & Masking practice question from the ASE B2 Painting & Refinishing Practice Test, with the correct answer and a short explanation.

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1. A featheredged dent has exposed bare steel that will be filled with polyester body filler. Painter A says metal conditioner should be applied to the bare steel first to improve filler adhesion. Painter B says a self-etching primer should be sprayed on the bare steel before the filler. Who is right?
- A.Neither A nor B✓ Answer
- B.A only
- C.Both A and B
- D.B only
Polyester body filler is designed to bond to clean, sanded bare metal (or to epoxy primer when the filler's data sheet allows it). Acid-based metal conditioners and self-etching primers leave an acidic layer that interferes with polyester filler adhesion, so neither belongs under the filler.
Ref QB-MJPSE7Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (substrate treatment and undercoat; official sample on metal conditioner under plastic filler)Report a problem with this question
2. A painter is preparing a bare aluminum fender for undercoat in a shop that mostly repairs steel panels. Which practice best prevents galvanic corrosion under the new finish?
- A.Using primer-surfacer straight over the bare aluminum to seal out moisture
- B.Using the same discs as on steel, then wiping the panel with solvent cleaner
- C.Using discs and tools kept only for aluminum, so no steel dust embeds✓ Answer
- D.Using a steel wire wheel to open the surface so the primer can grip it better
Steel particles embedded in aluminum create a dissimilar-metal cell that corrodes the aluminum under the paint, so aluminum must be worked with dedicated abrasives and tools. Primer-surfacer is a filler, not the treatment for bare aluminum, which needs an aluminum-compatible etch or epoxy primer system.
Ref QB-43HMU6Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (substrate identification and treatment: aluminum); I-CAR refinish training principlesReport a problem with this question
3. Before refinishing a panel with an unknown existing finish, a painter rubs an inconspicuous spot with a lacquer-thinner-dampened cloth. The finish softens and color transfers to the cloth. What does this indicate?
- A.The finish is a cured urethane that can be topcoated without any added sealer
- B.The finish is solvent-sensitive and needs a sealer or barrier before refinishing✓ Answer
- C.The finish is contaminated with silicone and must be cleaned with a degreaser
- D.The finish is an enamel that accepts primer-surfacer directly without lifting
A finish that dissolves under lacquer thinner is a solvent-sensitive (lacquer-type) finish; strong solvents in new undercoats or topcoats would attack it and cause lifting, so it must be isolated with a sealer or barrier coat, or removed. A cured urethane or catalyzed enamel resists the rub test.
Ref QB-KJBF96Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (identify substrate and existing finish; apply suitable treatment or undercoat)Report a problem with this question
4. A painter is repairing a zinc-coated (galvanized) steel door skin. All of these are recommended practices EXCEPT:
- A.Checking the primer data sheet to confirm it is approved for use over zinc
- B.Using epoxy primer over the zinc where the paint system specifies it
- C.Keeping the sanding confined so the zinc is not removed beyond the repair
- D.Assuming every acid-etch primer bonds to zinc as well as to bare steel✓ Answer
Zinc reacts differently from bare steel, and some acid-etch products are not recommended over galvanized coatings, so compatibility must be confirmed on the data sheet rather than assumed. Preserving the zinc layer and using epoxy primer where specified keep the factory corrosion protection intact.
Ref QB-336AP5Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (substrate treatment: galvanized steel); paint manufacturer technical data sheet practiceReport a problem with this question
5. Painter A says reverse masking, rolling the paper back on itself at the edge of a spot-prime area, leaves a soft primer edge with no hard tape line. Painter B says back-taping a door opening from behind the gap keeps a hard paint ridge from building at the panel edge. Who is right?
- A.B only
- B.A only
- C.Neither A nor B
- D.Both A and B✓ Answer
Both describe correct masking methods. Reverse masking lifts the paper edge so primer feathers out softly instead of stopping at a sharp tape line, and back-taping places the tape behind the gap so overspray tapers off at the opening instead of building a visible ridge.
Ref QB-JJY445Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (mask and protect areas not refinished, including reverse masking and back-taping)Report a problem with this question
6. Why should newspaper not be used to mask a vehicle for priming and painting?
- A.It is too heavy for masking tape, so it sags onto the wet paint during spraying
- B.It is too stiff to fold around curves, so the masking tape will not hold it down
- C.It is porous, so solvent soaks through it and its ink can transfer to the finish✓ Answer
- D.It builds a static charge that pulls dust, so it may be used only under clearcoat
Newspaper is porous and not solvent-resistant, so spray solvents and overspray bleed through it and the printing ink can dissolve onto the surface beneath. Solvent-resistant masking paper or plastic sheeting is made to stop bleed-through. Weight, stiffness and static are not why newspaper is ruled out.
Ref QB-23TXG4Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (mask and protect areas that will not be refinished)Report a problem with this question
7. A two-tone has just been sprayed along a fine-line tape edge. How should the masking tape be removed to avoid tearing or lifting the fresh paint edge?
- A.Once the paint skins over, pulling it toward the paint so it lies flat as it comes
- B.Right after the last coat, pulling it straight up at a right angle to the panel
- C.The next day after full cure, pulling it quickly so it does not stretch or tear
- D.At the time the data sheet recommends, pulling it back low and away from the edge✓ Answer
Pulling tape back on itself at a low angle, away from the fresh paint, at the removal time the product calls for lets the paint film break cleanly at the tape edge. Pulling straight up or toward the paint, or waiting until the film is hard and bonded over the tape, can tear the edge or leave a ragged ridge.
Ref QB-HJMSW3Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (mask and protect areas not refinished); paint manufacturer technical data sheet practiceReport a problem with this question
8. To save time, a painter applies primer-surfacer to a repair in one very heavy, wet coat instead of several medium coats. Which problem is most likely to result?
- A.Trapped solvent makes it shrink later, so sand scratches and the repair outline show✓ Answer
- B.It bridges scratches less, since one wet coat flows down into every scratch fully
- C.It cures faster with less shrinkage, since fewer layers hold less trapped solvent
- D.It protects the steel better, since one thick film seals out moisture by itself
A single heavy coat seals its surface before the solvent underneath can escape, so the film keeps shrinking after it is sanded and topcoated, and sand scratches or the repair outline reappear. Several medium coats with proper flash time between them release solvent, dry faster and cause less bridging.
Ref QB-Z2FMB3Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (mix and apply primer-surfacer; official sample on multiple coats with flash time)Report a problem with this question
9. Painter A says primer-surfacer is normally sprayed with a larger fluid tip and needle than clearcoat, as the gun and coating data sheets recommend. Painter B says primer-surfacer should be extended well past the featheredge onto unsanded paint so the repair blends in. Who is right?
- A.Neither A nor B
- B.Both A and B
- C.A only✓ Answer
- D.B only
High-build primer-surfacer is heavier-bodied than clearcoat, so the fluid nozzle and needle are chosen by coating type and are typically larger. Primer-surfacer should stay within the sanded repair area, because primer over unsanded paint has poor adhesion and can peel or lift.
Ref QB-GJ9FR2Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (mix and apply primer-surfacer; official sample on selecting fluid nozzle by coating type)Report a problem with this question
10. A featheredged repair with no bare metal exposed still shows coarse sand scratches and a few slight low spots. Which undercoat should be applied next?
- A.Urethane primer-surfacer, built up in several coats and then block sanded✓ Answer
- B.Adhesion promoter, applied in a light coat across the whole panel surface
- C.Primer-sealer, applied in one coat and then topcoated without sanding
- D.Self-etching primer, applied in a thin coat to fill and level the scratches
Primer-surfacer is the high-build, sandable undercoat made to fill sand scratches and minor low spots, after which it is block sanded level. Primer-sealer is a non-sanding coat for uniform holdout just before color, while self-etching primer and adhesion promoter are thin adhesion coats that do not fill.
Ref QB-65B88ZSource: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (mix and apply primer-surfacer); I-CAR refinish training principlesReport a problem with this question
11. Why do refinish technicians generally prefer two-component polyester finishing filler over one-part lacquer-based spot putty for filling deep sand scratches?
- A.One-part putty cures so hard with its hardener that it cannot be block sanded flat
- B.One-part putty dries only by solvent loss and may keep shrinking under paint✓ Answer
- C.Two-part glaze can be built up thick enough to replace body filler on small dents
- D.Two-part glaze needs no primer over it, because it seals the repair area by itself
Lacquer-based spot putty has no hardener; it dries only as solvent evaporates, so it can continue to shrink after topcoating and let sand scratches or edges show through. Catalyzed polyester glaze cures chemically with minimal shrinkage, but it is still applied in thin coats and covered with primer-surfacer or sealer.
Ref QB-PMGDTZSource: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (apply finishing filler to minor surface imperfections); I-CAR refinish training principlesReport a problem with this question
12. To make it cure faster, a technician mixes a much larger amount of hardener into polyester finishing filler than the label calls for. What problem is most likely in the finished repair?
- A.Longer working time, because the surplus hardener slows the reaction
- B.A soft, gummy filler that clogs the paper because it never fully cures
- C.Peroxide bleed-through staining the color coat over the filled area✓ Answer
- D.Better adhesion, because the surplus hardener etches the primer below
Unreacted peroxide hardener left in over-catalyzed polyester migrates into the topcoat and discolors it, a defect called peroxide bleed-through. A soft, gummy result comes from too little hardener, not too much, and extra hardener shortens working time.
Ref QB-55YV2YSource: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (apply finishing filler); paint manufacturer technical data sheet practiceReport a problem with this question
13. Painter A says areas glazed with finishing filler can be left bare under the basecoat, because the filler is already sanded smooth. Painter B says finishing filler should be applied in thin, tight coats over sanded body filler or sanded primer-surfacer. Who is right?
- A.Both A and B
- B.B only✓ Answer
- C.Neither A nor B
- D.A only
Finishing filler is meant for minor imperfections and goes on thin and tight over sanded filler or primer-surfacer. It is porous and absorbs differently from the surrounding area, so it must be covered with primer-surfacer or sealer, as the data sheet directs, before basecoat.
Ref QB-NM53NYSource: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (apply finishing filler to minor surface imperfections)Report a problem with this question
14. After block sanding a primed repair, a painter sees a few small areas that still hold the guide coat while the surrounding primer is already sanded clean and level. What should be done?
- A.Add glaze or primer-surfacer to the low spots, then guide-coat and block again✓ Answer
- B.Switch to a coarser grit and sand the whole panel until the guide coat disappears
- C.Leave the guide coat on those spots, since the sealer and basecoat will hide them
- D.Keep sanding just those spots with fingertip pressure until the guide coat is gone
Guide coat that remains after the surrounding area is level marks low spots; sanding harder only cuts down the good surface around them and finger pressure creates waves. The cure is to add material to the low spots and block sand again until the guide coat comes off evenly.
Ref QB-852WJ3Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (block sand primer-surfacer and finishing filler); I-CAR refinish training principlesReport a problem with this question
15. Why should primer-surfacer on a door panel be sanded with a long sanding block rather than with sandpaper held flat under the hand?
- A.The block feathers the primer edge faster, since it applies uneven pressure
- B.The block cuts faster, so the primer can be sanded before it has fully cured
- C.The block lets the guide coat be skipped, since its flat face finds highs by feel
- D.The block spans the highs, so it levels the surface instead of following waves✓ Answer
A rigid or contour-matched block spans low areas and cuts the high spots first, producing a straight, level surface. Hand or finger pressure follows existing waves and digs grooves, and blocking does not replace full cure or the guide coat that shows highs and lows.
Ref QB-RM7364Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (block sand area to which primer-surfacer has been applied)Report a problem with this question
16. All of these are correct practices when block sanding primer-surfacer before topcoat EXCEPT:
- A.Letting the primer fully cure as its data sheet directs before sanding
- B.Wet sanding a primer even though its data sheet says to dry sand it only✓ Answer
- C.Re-priming any spot where the sanding has broken through to bare metal
- D.Finishing with the finer grit that the topcoat data sheet specifies
Some primers are dry-sand only because water absorbed into the film can be trapped under the topcoat and cause blistering or adhesion loss. Full cure before sanding, re-priming sand-throughs with the proper undercoat, and finishing with the finer grit the topcoat requires are all correct.
Ref QB-75PJD2Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (block sand primer-surfacer); paint manufacturer technical data sheet practiceReport a problem with this question
17. The joint between a newly welded quarter panel and the wheelhouse will be seam sealed. What should be done to the joint before the sealer is applied?
- A.Sand it to clean bare metal so the sealer can bond directly to the steel in the joint
- B.Apply and cure the topcoat first, then run the sealer bead over the cured color
- C.Apply primer-surfacer and block sand it smooth so the sealer bead lies perfectly flat
- D.Clean it and coat it with a corrosion-resistant primer such as epoxy, per the sealer maker✓ Answer
Seam sealer laid on bare steel can trap moisture against the metal and let rust start under the bead, so the joint is cleaned and given a corrosion-resistant primer, usually epoxy, as the sealer manufacturer directs. The sealer is then refinished over so the joint matches the factory appearance.
Ref QB-QMUQY2Source: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (prepare surfaces for seam sealer application); I-CAR corrosion protection principlesReport a problem with this question
18. Painter A says seam sealer can be topcoated as soon as its surface skins over, because the paint will seal the rest. Painter B says seam sealer may be laid directly on bare steel, because the sealer itself keeps moisture out of the joint. Who is right?
- A.Both A and B
- B.Neither A nor B✓ Answer
- C.A only
- D.B only
A skin does not mean the sealer is cured; painting uncured or incompatible sealer can cause cracking, wrinkling or adhesion loss, so the cure and paintability guidance must be followed. Sealer over bare steel can trap moisture and start rust, so it belongs over a corrosion-resistant primer.
Ref QB-25WVHUSource: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (prepare surfaces for seam sealer; evaluate seam sealer application prior to refinishing)Report a problem with this question
19. After a painter sands a layer of polyester body filler, many tiny pinholes appear across its surface. What is the most likely cause?
- A.Air whipped into the filler by stirring it rapidly while mixing in the hardener✓ Answer
- B.Metal sanded so clean before filling that the filler could not grip the steel
- C.Filler pressed on in thin, tight passes that forced it into the sand scratches
- D.Filler sanded with a finer grit than the featheredge before primer was applied
Whipping or stirring filler and hardener rapidly folds air bubbles into the mix, and sanding later opens them as pinholes. Filler should be mixed by folding and pressing on a clean board and applied in thin, tight passes, which forces air out rather than trapping it.
Ref QB-JM335VSource: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (identify pinholes, determine the causes and correct the condition)Report a problem with this question
20. Pinholes are found in sanded body filler on a fender that is about to be primed. What is the correct way to fix them?
- A.Force-dry the filler with heat so trapped air escapes, then prime it
- B.Spray a heavy coat of primer-surfacer so the primer fills every pinhole
- C.Fill them with finishing filler, level it, then prime and block sand✓ Answer
- D.Spray extra-wet basecoat coats so the color flows down into the holes
Pinholes must be filled with finishing (glazing) filler and sanded before priming; primer or color sprayed over them bridges the holes, traps solvent and air, and the holes reopen or show as solvent pop. Heat does not close existing pinholes and can make trapped air and solvent erupt.
Ref QB-ZYKPPFSource: ASE Collision Repair and Refinish Study Guide, Test B2 Painting and Refinishing task list (identify pinholes, determine the causes and correct the condition)Report a problem with this question

2. A painter is preparing a bare aluminum fender for undercoat in a shop that mostly repairs steel panels. Which practice best prevents galvanic corrosion under the new finish?

3. Before refinishing a panel with an unknown existing finish, a painter rubs an inconspicuous spot with a lacquer-thinner-dampened cloth. The finish softens and color transfers to the cloth. What does this indicate?

4. A painter is repairing a zinc-coated (galvanized) steel door skin. All of these are recommended practices EXCEPT:

5. Painter A says reverse masking, rolling the paper back on itself at the edge of a spot-prime area, leaves a soft primer edge with no hard tape line. Painter B says back-taping a door opening from behind the gap keeps a hard paint ridge from building at the panel edge. Who is right?

6. Why should newspaper not be used to mask a vehicle for priming and painting?

7. A two-tone has just been sprayed along a fine-line tape edge. How should the masking tape be removed to avoid tearing or lifting the fresh paint edge?

8. To save time, a painter applies primer-surfacer to a repair in one very heavy, wet coat instead of several medium coats. Which problem is most likely to result?

9. Painter A says primer-surfacer is normally sprayed with a larger fluid tip and needle than clearcoat, as the gun and coating data sheets recommend. Painter B says primer-surfacer should be extended well past the featheredge onto unsanded paint so the repair blends in. Who is right?

10. A featheredged repair with no bare metal exposed still shows coarse sand scratches and a few slight low spots. Which undercoat should be applied next?

11. Why do refinish technicians generally prefer two-component polyester finishing filler over one-part lacquer-based spot putty for filling deep sand scratches?

12. To make it cure faster, a technician mixes a much larger amount of hardener into polyester finishing filler than the label calls for. What problem is most likely in the finished repair?

13. Painter A says areas glazed with finishing filler can be left bare under the basecoat, because the filler is already sanded smooth. Painter B says finishing filler should be applied in thin, tight coats over sanded body filler or sanded primer-surfacer. Who is right?

14. After block sanding a primed repair, a painter sees a few small areas that still hold the guide coat while the surrounding primer is already sanded clean and level. What should be done?

15. Why should primer-surfacer on a door panel be sanded with a long sanding block rather than with sandpaper held flat under the hand?

16. All of these are correct practices when block sanding primer-surfacer before topcoat EXCEPT:

17. The joint between a newly welded quarter panel and the wheelhouse will be seam sealed. What should be done to the joint before the sealer is applied?

18. Painter A says seam sealer can be topcoated as soon as its surface skins over, because the paint will seal the rest. Painter B says seam sealer may be laid directly on bare steel, because the sealer itself keeps moisture out of the joint. Who is right?

19. After a painter sands a layer of polyester body filler, many tiny pinholes appear across its surface. What is the most likely cause?

20. Pinholes are found in sanded body filler on a fender that is about to be primed. What is the correct way to fix them?

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