Answer
For oil-based primer, use 320 or 400 after it cures. Use 600 for finer topcoat prep.
Why it happens
Primer needs to cure before sanding; sanding too early can clog paper and smear the surface.
Recommended grit
Use 320 or 400 after the primer is fully cured. Use 600 for finer topcoat prep.
Wet or dry
Dry.
Success check
The primer powders cleanly and feels smooth before painting.
What to do
- Let the primer cure as directed.
- Sand with 320 or 400 using light pressure.
- Use 600 for finer finish prep.
- Remove all dust before paint.
Avoid: Do not sand oil-based primer while it is soft.