Answer
Sharp edges can cut the sheet. Use lighter pressure, soften the edge with controlled passes, and keep the sheet backed or supported instead of dragging a loose edge across the corner.
Why it happens
A sharp workpiece edge can slice or catch the paper backing, especially when the sheet is loose or pulled tightly.
Recommended grit
Use 120 or 180 to break a sharp edge, then refine with 220 and 320 when a smoother edge is needed.
Wet or dry
Use dry sanding for most edge shaping. Use wet sanding only when the material is water-safe and the sheet is supported.
Success check
The edge is slightly eased and the sheet no longer catches or tears during sanding.
What to do
- Inspect the edge that is tearing the sheet.
- Use a backed piece of sandpaper or a sanding block when possible.
- Sand with light passes along the edge instead of pulling hard across it.
- Use 120 or 180 to slightly break the sharp edge.
- Move to 220 and 320 after the edge is no longer cutting the sheet.
- Keep the working piece of sheet flat and supported.
- Replace torn pieces before they scratch the surface.
Avoid: Do not drag a loose unsupported sheet hard across a sharp corner. The edge can slice the backing.