Answer
Use 120, then 180, then 220 or 320. Do not jump straight from 80 to fine grits.
Why it happens
80 grit is a heavy removal grit. Its scratch pattern must be refined with medium grits before finishing.
Recommended grit
Step through 120, 180, then 220 or 320.
Wet or dry
Dry for early removal and general prep.
Success check
The surface shows one even finer scratch pattern with no isolated 80-grit lines.
What to do
- Clean dust and loose debris from the surface.
- Sand evenly with 120 grit until the 80-grit lines become lighter.
- Move to 180 grit, then 220 or 320.
- Inspect under good light before moving finer.
Avoid: Do not jump from 80 directly to 320 or finer.