Answer
For spray paint prep, use 320 or 400. Use 600 for finer topcoat prep.
Why it happens
Spray paint needs a clean, dull surface with scratches fine enough to be covered by primer or paint.
Recommended grit
Use 320 or 400 for general spray paint prep. Use 600 for finer topcoat prep.
Wet or dry
Dry for most prep; wet for fine finishing stages when the coating instructions allow it.
Success check
The surface is clean, dull, and evenly sanded before spraying.
What to do
- Clean the surface.
- Sand with 320 or 400 for primer or paint prep.
- Use 600 for finer topcoat prep.
- Remove all dust before spraying.
Avoid: Do not spray paint over dust or glossy unsanded surface.