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Problem

What grit for fiberglass door before painting?

Paint on a fiberglass door can peel or show sanding scratches if prep is too coarse.

paint primer dry sanding between coats
Answer

For a fiberglass door before painting, scuff with 220 or 320, then refine visible areas with 400.

Why it happens
Fiberglass doors need cleaning and light scuff sanding so primer or paint can grip.
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 scuffed before coating.

What to do

  1. Clean the door with the correct cleaner for the coating system.
  2. Scuff the surface evenly with 220 or 320.
  3. Refine smooth visible areas with 400.
  4. Remove all dust before primer or paint.
Avoid: Do not use coarse grit that cuts into the fiberglass skin.

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