Answer
Use 320 or 400 on primer before paint. Use 600 for finer final primer prep.
Why it happens
Primer needs to be smoothed without removing too much material.
Recommended grit
Use 320 or 400 on primer before paint. Use 600 for finer final primer prep.
Wet or dry
Dry for most primer prep; wet only when the primer or paint system allows it.
Success check
Primer is smooth, dull, and clean before paint.
What to do
- Let the primer cure as directed.
- Sand evenly with 320 or 400.
- Use 600 for finer final primer prep.
- Clean all dust before painting.
Avoid: Do not sand primer before it is ready.