Answer
For pine before staining, sand dry with 120 only where needed, then 180 and 220 with light pressure.
Why it happens
Pine is soft, so coarse scratches and uneven pressure can show strongly after stain.
Recommended grit
Use 120 for rough areas, then 180 and 220 before staining.
Wet or dry
Dry.
Success check
The pine feels even and has no visible sanding lines before stain.
What to do
- Sand with the grain using light pressure.
- Use 120 only for rough or uneven areas.
- Refine with 180, then 220.
- Remove dust before stain.
Avoid: Do not press hard on soft pine.