Answer
For pine before painting, use 120 on rough areas, then 180 and 220.
Why it happens
Soft pine needs enough smoothing before primer without leaving coarse marks.
Recommended grit
Use 120 on rough areas, then 180 and 220 before primer or paint.
Wet or dry
Dry.
Success check
The pine feels smooth and shows no coarse scratch lines.
What to do
- Sand rough pine with 120.
- Refine with 180.
- Finish prep with 220.
- Remove dust before primer or paint.
Avoid: Do not paint over raised grain or dust.