Quick answer: For woodworking, start with aluminum oxide – it's the grain that fractures cleanly under heat and pressure and gives the best finish for the money. Use semi-open or open coat so resinous wood doesn't load the belt, cloth backing for belts and paper for finish discs and the last head on a wide belt sander, and follow a grit sequence like 80, 120, 150, 180 on belts and finish with 220 on a random orbital – never skipping more than one grit. Save zirconia and ceramic for heavy stock removal.
Sandpaper advice varies from person to person, but the basics don't. Choosing the right abrasive for a woodworking operation comes down to four things: grit, coat (grain spacing), backing, and grain. Here's how each one works and what we recommend.
Know your grits
Grit describes the size of the abrasive particles – the lower the number, the larger and coarser the grain. A 36-grit grain is far bigger and cuts far more aggressively than a 120-grit grain.
| Range | Grits | Job |
|---|---|---|
| Coarse | 24–80 | Stock removal, flattening, stripping |
| Medium | 80–150 | Dimensioning, removing coarse scratches |
| Fine | 180–220 | Final sanding before stain or finish |
| Very fine | 240–280 and up | Between finish coats |
A typical belt sequence in wood fabrication is 80, 120, 150 and 180, then a blend with a jitterbug or random orbital sander at 220. Each grit's only job is to remove the scratches left by the grit before it, so if you skip too far – 80 straight to 180 – the fine grit can't clear the coarse scratches and you'll see them the moment stain goes on. Blend evenly across the whole piece or you'll get ripples and an inconsistent finish. See our US vs. European grit grading guide if your paper is marked with "P" numbers.
Coat: open, semi-open or closed
| Coat | Grain coverage | Use for |
|---|---|---|
| Closed coat | Nearly 100% | Hardwoods – ash, birch, cherry, maple, oak, mahogany – and all metal. Most grain, longest life, most aggressive cut. |
| Semi-open coat | About 30% less grain than closed | Our standard woodworking belt. Fits almost every job and still gives long life. |
| Open coat | 50–70% | Resinous softwoods – pine, cedar, fir, redwood, hemlock, cypress – where sap and dust pack the belt. |
Loading is the reason coat matters. When sap and dust pack the spaces between grains, the belt turns into a smooth surface that rubs instead of cutting, then burns. Open coat leaves room for that debris to fall out. If you're fighting loading on softwood, ask us for open coat. (An abrasives rep once told us there was no such thing as semi-open coat – "that's like being half pregnant." He was wrong. It's what's on our woodworking belt pages, and it works.) More in open coat vs. closed coat.
Backing: paper or cloth
Paper
In woodworking, paper backing shows up on two products: sanding discs and wide belts. Paper discs are usually gold or white, 5" or 6", plain or with a hole pattern, and come in PSA or hook & loop. Paper wide belts are popular for wide belt sanders because the splice is thinner (less chatter), they cost less than cloth, and they leave a better finish on the final pass. The paper wide belt we carry – Sun Abrasives B317, an E/F-weight paper – is regarded as one of the best woodworker paper belts on the market. Pro tip: run a paper belt on the last head, or the last grit, of your sanding sequence.
Cloth
Cloth is the most common backing across every industry – woodworking, metalworking, glass – because it's heavier-duty, usually a polyester-cotton blend. The polyester makes cloth belts tolerant of water, which matters in metal shops, and in a wood shop it means you can power-wash the sap and debris out of a loaded belt. That one trick extends belt life by 15–20%. The trade-off on a wide belt sander is a thicker splice that can, occasionally, chatter; on a narrow belt it's the only backing worth buying. See J, X and Y weights for how cloth weights differ.
Grain: aluminum oxide, zirconia or ceramic
| Grain | Grits available | Use in woodworking |
|---|---|---|
| Aluminum oxide | 24–220 and finer | Almost everything. Fractures cleanly under heat and pressure ("friability"), so it stays sharp and gives the best finish. |
| Zirconia | 24–120 | Heavy stock removal, dimensioning, particle board and glue lines. Cooler and longer-lived than aluminum oxide; not for finishing. |
| Ceramic | 24–120 | The hardest-working grain for removal. Least heat, least loading on resinous or oily wood. |
Zirconia and ceramic are hard, tough grains that don't break down easily, so they're used almost exclusively for stock removal, and they only come in coarse grits. They're not common in general woodworking, but you'll see them in particle board plants and anywhere large blocks are ground down – and they generate less heat, so they load less on resinous, oily or glued wood. Pro tip: if you're burning maple or cherry on a wide belt sander, switch the grinding heads to zirconia or ceramic. For everything else, aluminum oxide is the answer; our aluminum oxide vs. zirconia guide compares them in detail.
Our recommendation
| Operation | Belt or disc |
|---|---|
| Wide belt sander, calibrating heads | Zirconia or ceramic cloth, 36–80 |
| Wide belt sander, finishing head | Aluminum oxide paper (B317), 120–180 |
| Edge and stroke sanders | Aluminum oxide cloth, semi-open, 80–150 |
| Random orbital finish | Gold aluminum oxide hook & loop discs, 150–220 |
| Resinous softwood, any machine | Open coat aluminum oxide |
Shop woodworking abrasives, wide belts and gold discs – or tell us your machine and your wood and we'll spec it for you.
