Answer
For outdoor sign boards, use 120 on rough areas, then 180 and 220 before paint.
Why it happens
Exterior boards need roughness removed and old glossy paint scuffed before primer or paint.
Recommended grit
Use 120 for rough weathered areas, then 180 and 220 before paint.
Wet or dry
Dry.
Success check
The board is dry, smooth, and evenly scuffed before paint.
What to do
- Clean and dry the sign board.
- Use 120 on rough or peeling areas.
- Refine with 180 and 220.
- Remove dust before exterior primer or paint.
Avoid: Do not paint over loose paint, damp wood, or sanding dust.