Answer
Dust scratches usually mean debris is trapped under the sheet. Clean the surface often, use lighter pressure, and step finer instead of continuing with a dirty or worn sheet.
Why it happens
Loose dust, clogged abrasive, or heavy pressure can drag particles across the surface and create random scratches.
Recommended grit
Use the grit needed for the task, then refine one step finer after cleaning. For prep work, move from 220 to 320 or from 320 to 400.
Wet or dry
Use dry sanding when the material must stay dry. Use wet sanding on water-safe surfaces to help carry away fine residue.
Success check
The scratch pattern becomes consistent again and random drag marks are no longer appearing.
What to do
- Stop sanding when random scratches appear.
- Wipe or vacuum the surface before continuing.
- Check the sandpaper for loading or trapped particles.
- Replace the sheet when it is clogged or worn.
- Resume with lighter pressure and a clean sanding direction.
- Move one grit finer after the surface is clean.
- Inspect under good light before applying finish.
Avoid: Do not keep sanding with a loaded sheet. Trapped dust can scratch like a coarser grit.