Answer
For a garage door, clean first, scuff with 220 or 320, then use 400 on smoother panels.
Why it happens
A garage door needs cleaning, scuff sanding, and finer prep on visible panels.
Recommended grit
Use 220 or 320 for scuffing, then 400 for smoother visible areas.
Wet or dry
Dry.
Success check
The door is clean, dull, and ready for coating.
What to do
- Wash and dry the garage door.
- Scuff old paint with 220 or 320.
- Use 400 on smooth visible panels.
- Remove dust before primer or paint.
Avoid: Do not paint over chalky, dusty, or glossy old paint.