There are two basic things amongst many other things to check in a plywood. One is the flatness, and another is the edge. Both matters highly. There are many other factors too, which ensures that you are picking a ply of the best quality.
General checking that would help you choose quality plywood sheets
- Inspect the plywood for flatness, and see that the whole sheet is almost flat. Total flatness is the best for working. Some sheets stay warped at places, and you should not pick them. No sheet would be perfect. But at least the flattest ones would be the ideal pick.
- Inspect edges of the sheet. The core veneers which are viewable from the sheet edge should have uniform thickness. If the gaps are a lot between the veneers, then you can assume same or worse state inside the sheet. Hence check for this to be sure.
- The layers of the veneer should be overlapping too much or else it would affect the quality.
- The ply must have good capacity to hold nails. This can be tested by hammering a nail along the edge of the wood. If you see the ply snap at that point, then be sure that itsstructuralstrength is poor. Avoid those sheets.