Grit comparison chart
FEPA grades carry a P prefix and are the European standard. CAMI numbers have no prefix and are the North American one. They are close up to about 220 and diverge sharply above it, which is why a P600 paper feels far finer than a 600 grit one.
If the paper has a P, use the P column. If it does not, use the CAMI column.
| FEPA (P) | CAMI | Particle size (µm) | Use |
|---|---|---|---|
| P40 | 36 | 425 | Heavy stock removal, paint stripping |
| P60 | 60 | 269 | Shaping, levelling filler |
| P80 | 80 | 201 | Shaping, removing mill marks |
| P100 | 100 | 162 | General purpose |
| P120 | 120 | 125 | Final shaping, first pass on bare wood |
| P150 | 150 | 100 | Smoothing |
| P180 | 180 | 82 | Final sanding before finish on softwood |
| P220 | 220 | 68 | Final sanding on hardwood |
| P320 | 280 | 46 | Between finish coats |
| P400 | 320 | 35 | Between coats, wet sanding |
| P600 | 360 | 26 | Wet sanding, primer |
| P800 | 400 | 22 | Wet sanding clearcoat |
| P1200 | 600 | 15 | Compounding preparation |
| P2000 | 1000 | 10 | Polishing preparation |
Which grit to use and in what order
Start with the coarsest grit that removes the defect, then work up. Do not skip more than one grade at a time: each grit is there to remove the scratch pattern the last one left, and jumping from P80 to P220 leaves scratches that only show up under finish.
A typical bare wood sequence is P80, P120, P180 and stop. Going finer than P180 on softwood burnishes the surface and stain will go on patchy.
On paint work the sequence continues wet: P400 to flatten, P800 to remove the P400 scratches, P1200 before compounding.
| Job | Start | Finish |
|---|---|---|
| Stripping paint or varnish | P40 to P60 | P120 |
| Levelling rough sawn timber | P60 | P150 |
| Preparing bare softwood | P100 | P180 |
| Preparing bare hardwood | P120 | P220 |
| Between coats of finish | P320 | P400 |
| Deburring mild steel | P80 | P180 |
| Wet sanding clearcoat | P800 | P2000 |
120 grit and 400 grit in practice
P120 is the workhorse. It is aggressive enough to take out planer marks and fine enough that P180 will clear its scratches in one pass. If you only stock one grit, stock this one.
P400 is the first genuinely fine grade and it is where wet sanding starts. Used dry it clogs almost immediately on paint, so run it wet with a drop of detergent in the water. Used between coats of finish it should knock off nibs without cutting through.
