Abrasive choice decides how much time a repair takes and how good it looks under a topcoat. Too coarse and you leave scratches the primer can't fill. Too fine and you spend an hour doing a job that should take ten minutes — and you may not give the next coat enough key.
Understanding P-grades
European abrasives use the FEPA "P" scale — P80, P240, P800 and so on. Higher numbers mean finer particles. The scale is not linear, and the useful thing to remember is the progression rule: each grade should remove the scratches left by the one before it.
Jumping from P80 straight to P320 doesn't work. The finer paper polishes the peaks of the coarse scratches without removing their depth, so they stay — and they reappear the moment colour goes on.
A working progression
Treat this as a guide rather than a rule; always check the data sheets for the filler, primer and paint system you're using, as these vary between manufacturers.
P40–P80 — stripping and shaping
Removing paint back to bare metal, keying metal before filler, and initial shaping of cured filler. Aggressive and fast, leaving deep scratches that must be refined out.
P120–P180 — refining filler
Taking the shape down after coarse work and removing P80 scratching. Most of the actual shaping of a repair happens here.
P240–P320 — pre-primer
Final filler refinement and feather-edging surrounding paint. A high build primer will fill scratches from around this range comfortably.
P400–P600 — primer flatting
Flatting cured primer before basecoat. P400 to P500 dry is common; some systems specify wet flatting.
P800–P1500 — pre-paint and blending
Final key before basecoat, denibbing, and preparing blend panels. Flexible foam-backed abrasives come into their own here — they follow curves, swage lines and edges where a rigid block would cut through.
P2000 and finer — finishing
Removing runs, dust nibs and orange peel from cured clearcoat before compounding and polishing.
Dry, wet, and dust extraction
Wet flatting lubricates the cut and stops clogging, but introduces water near bare metal and takes drying time. Dry sanding with extraction is faster and keeps the panel dry — the reason net abrasives have largely taken over in production bodyshops. Abranet strips extract dust through the mesh across the whole face, so the abrasive keeps cutting rather than loading up, and the surface stays visible while you work.
Practical habits worth keeping
- Change paper before it stops cutting. A worn sheet burnishes rather than cuts, and generates heat.
- Use a block or pad on flat panels. Finger pressure makes hollows that only appear under gloss.
- Cross-hatch. Changing direction between grades makes it obvious when the previous scratches are gone.
- Clean between grades. One stray coarse grain dragged into a fine stage puts a scratch through everything.
- Blow off and degrease before coating. Sanding dust in primer is a guaranteed comeback.
Stocking abrasives
Abrasives are one of the highest-turnover consumables in a bodyshop, and the per-sheet cost drops sharply in trade quantities. Browse abrasives and bodyshop supplies or the trade bundles for bulk packs.
