Answer
For plywood edges, use 120 first, then 180 and 220 before finishing.
Why it happens
Layered plywood edges need coarser smoothing first, then finer grits to reduce splinters.
Recommended grit
Use 120 for rough edges, then 180 and 220 before paint or finish.
Wet or dry
Dry.
Success check
The edge feels smooth with no loose splinters.
What to do
- Remove loose splinters first.
- Sand rough edges with 120 grit.
- Refine with 180 and 220.
- Remove dust before finish or edge sealing.
Avoid: Do not over-round plywood edges unless that is the intended shape.