Baltic birch grows in the Baltic regions of both Russia and Finland. The best grades of Baltic birch plywood come from trees harvested in Finland, says Inside Woodworking. The excellent health of birch trees in the Baltic regions contributes to the higher quality of this building material, since the timber contains fewer flaws than found in birch trees from other areas. Nearly perfect veneers cut from these logs yield gap-free sheets of stable plywood.
After soaking and peeling birch logs, sawmills shear sheets of birch from logs by rotating the log against a wide cutting blade on a rotary veneer lathe. Many grades of ordinary plywood use imperfect interior layers, with gaps due to insect damage or other injuries. Baltic birch logs provide veneers without gaps, eliminating dents that form over voids. Baltic birch plywood uses five layers of birch veneer, shifting each sheet so that the grain runs at right angles to the grain of the sheet beneath.
Baltic birch plywood of the best grade has outer layers without flaws or patches, but less-expensive grades may include patches and flaws on one or both surfaces. Grade B features a continuous surface sheet with some small "pin" knots but no patches or mineral stains. Grade BB allows some larger solid knots and mineral streaks, as well as patched defects. Grade CP may include splits in the grain less than .5 mm wide. Grade C allows patches, splits in the surface, and knots with open flaws.
The best grades of Baltic birch plywood offer the quality necessary for the construction of fine cabinetry. The exterior presents a natural wood surface suitable for either staining or painting, without the puckering and swelling problems caused by thin layers of wood laid over empty spaces. Baltic birch plywood provides a strong base for skateboards, a flawless surface for tabletops, and fits many other projects requiring strength and stability.