Answer
For PETG prints, use light pressure: 220 or 320 for layer lines, then 400 and 600 before primer.
Why it happens
PETG can soften with heat and pressure, so sanding needs light pressure and gradual grits.
Recommended grit
Use 220 or 320 for layer lines, then 400 and 600 before primer.
Wet or dry
Dry; wet can help at finer stages to control heat and dust.
Success check
The print has smoother layer lines with no melted or gummy spots.
What to do
- Clean the PETG print.
- Sand layer lines lightly with 220 or 320.
- Refine with 400 and 600.
- Clean dust before primer or paint.
Avoid: Do not press hard enough to heat or smear PETG.