B2 Collision — Painting & Refinishing — practice test

High-yield B2 topics

The material that shows up year after year. If you're short on time, start here.

• Substrate ID and the right primer for it. Bare steel needs an etch or epoxy primer before anything else; bare aluminum and galvanized will not hold a standard etch the same way; e-coat that has been sanded through is no longer a sealed substrate. Know that self-etch primer over body filler is wrong - the acid attacks the filler - and that epoxy is the safe universal base under filler and over bare metal. Expect at least a few questions where the answer hinges on what is under the sandpaper.
• Sand scratch progression and what each grit is for. 80 grit for filler shaping, 180 for filler finishing, 320-400 dry under primer-surfacer, 400-600 wet before sealer/basecoat, 600-800 for blend panels, 1000-1500 for nib/color sanding, 1500-3000 before buffing. The classic failure mode is scratch swelling and mapping when you spray over too-coarse a scratch - the answer is almost always go back and refine the scratch, not add more primer. Also know feather-edge width and why a hard edge shows through.
• Mix ratios, reducer/hardener temperature selection, and viscosity. Understand 4:1:1 vs 2:1 style ratios and how to scale them, why a fast reducer in a hot booth causes dry spray and solvent pop and a slow reducer in a cold booth causes runs, sags, and trapped solvent, and that flash time between coats is not optional - it is the difference between good film and die-back or blistering. Know mil thickness targets: sealer thin, base to hiding only, clear typically two medium-wet coats to roughly 2 mils.
• HVLP gun setup and air supply. HVLP is legally capped at 10 psi at the air cap; know the difference between inlet pressure and cap pressure and why the transfer-efficiency rule exists. Fluid tip sizing (roughly 1.3-1.4 for base, 1.4-1.7 for clear and primer-surfacer), 6-8 in gun distance, 50-75 percent overlap, gun held perpendicular not arced. Arcing causes light ends and mottling. Also know that oil or water in the line is the cause behind fisheyes and craters just as often as silicone.
• Color matching, variance, and blending. Know how to use the paint code, the variant/alternate chips, and a sprayout card - and that a sprayout card is checked dry, under the same light the vehicle will be judged in, at the same angle. Metallic orientation shifts with gun distance, air pressure, reducer speed, and film build: too wet or too close makes metallics go dark and cloudy, too dry or too far makes them go light and rough. Blending into an adjacent panel is the fix for a close-but-not-exact match; a hard edge at a body line is a last resort, not the first answer.
• Defect cause-and-cure, especially the look-alikes. Solvent pop vs blistering vs die-back; fisheye vs crater; orange peel vs dry spray; lifting vs wrinkling; mottling vs tiger stripe. Each has a distinct cause chain - solvent pop is trapped solvent from too-heavy film or too-fast force-dry, lifting comes from solvent attacking an uncured or non-compatible underlying finish. Sanding it out is not the answer when the cause is under the film.

Where techs lose points on B2

Good technicians miss these — not from lack of skill, but because the question is built to catch them.

• "Add more clear/primer to fix it" is a distractor almost every time. When the defect is scratch mapping, solvent pop, or sand-through, building more film makes it worse. The test rewards going backward in the process - strip, re-prep, re-seal - not forward.
• Confusing air pressure at the regulator with pressure at the cap. A question that says the gun is set at 10 psi is describing cap pressure on an HVLP; inlet pressure will be much higher. Answer choices will deliberately mix the two, and there will be a choice that says HVLP runs at 40-50 psi at the cap - that is wrong by definition.
• The self-etch-over-everything reflex. Plenty of shops etch-prime whatever is in front of them, and the test knows it. Self-etch over body filler, over old finish, or under certain putties is a wrong answer even though guys do it daily. Epoxy is the answer more often than techs expect.
• Metallic that reads too dark and the reflex answer of "wrong color code." Nine times out of ten on this test it is application: too wet, too close, too much pressure drop, or wrong reducer for the temp. The fix is adjust technique and shoot a new sprayout card, not order a different code. Same with a mottled blend - that is gun handling, not paint.

A study plan that works for B2

Roughly two weeks of real preparation, in the order that actually builds on itself.

1. Days 1-4: Surface prep and substrates. Drill grit progression, feather-edge, which primer goes on which substrate, and why. Pull two real TDS sheets from whatever line your shop runs (PPG, BASF, Axalta, Sherwin) and read the primer and sealer pages front to back - the test is basically asking whether you can read a TDS.
2. Days 5-8: Mixing and application. Practice ratio math on paper until scaling a 4:1:1 to a partial quart is instant. Memorize the reducer/hardener temperature ranges and the flash-time logic. Then do gun-setup fundamentals: cap pressure, tip sizing, distance, overlap, and what each one does to a metallic.
3. Days 9-12: Defects. Make a two-column list of every defect on the task list with its cause chain and its correct repair. Force yourself to separate the look-alike pairs - solvent pop vs blister, fisheye vs crater, mottle vs tiger stripe. Say out loud what is under the film for each one.
4. Days 13-14: Timed practice at 65 questions in under two hours, then review only the misses and trace each back to which task area it came from. If your misses cluster in prep or mixing, that is the whole test - go back to those days rather than reading everything again.

Sample B2 questions

Straight from the bank — answers highlighted, with the explanation underneath.