Answer
EVA foam can be sanded only lightly. Use 220 or 320, then 400, with very light pressure.
Why it happens
Soft foam does not cut like wood or metal and can deform under pressure.
Recommended grit
Use 220 or 320 only for light shaping, then 400 for gentle smoothing.
Wet or dry
Dry.
Success check
The foam edge is smoother without tearing or heat damage.
What to do
- Test on scrap foam first.
- Use very light pressure with 220 or 320.
- Refine gently with 400.
- Stop if the foam tears or fuzzes.
Avoid: Do not press hard or use coarse grit aggressively on EVA foam.