Answer
For a painted metal door, scuff with 220 or 320, then use 400 on smooth visible panels.
Why it happens
Old coating needs cleaning, dulling, and edge blending before new primer or paint.
Recommended grit
Use 220 or 320 for scuffing, then 400 for smoother visible prep.
Wet or dry
Dry.
Success check
The door is clean, dull, and evenly prepared for coating.
What to do
- Clean the metal door first.
- Sand loose paint edges if present.
- Scuff the full surface with 220 or 320.
- Use 400 on smooth visible panels.
Avoid: Do not repaint over glossy or dusty metal door paint.