Answer
For plastic model seams, use 400 or 600, then 800, 1000, and 1500 before primer.
Why it happens
Small plastic seams need gradual refinement and light pressure to avoid gouges.
Recommended grit
Use 400 or 600 for seam cleanup, then 800, 1000, and 1500 for finer prep.
Wet or dry
Dry for shaping; wet for fine stages.
Success check
The seam feels smooth and does not show deep sanding scratches.
What to do
- Let glue or filler cure fully.
- Sand the seam with 400 or 600.
- Refine with 800 and 1000.
- Use 1500 before primer on visible plastic.
Avoid: Do not use heavy pressure that flattens nearby detail.