Birch Plywood – B4 (with softwood veneer core)
Our birch plywood has two birch veneer faces and a softwood veneer core (usually pine, fire, or spruce, but sometimes poplar). This is a north American product and like most softwood plywood, the edge may have some voids in it, so the edges are not typically left exposed. This plywood is sometimes called furniture grade plywood, and although that term does not always correspond to a specific grade, one face is very nice and can be finished to result in a professional-quality surface.
Laser cutting birch plywood works beautifully, with most lab cutters cutting up to 1/4 in and many cutting up to 1/2in or more. The laser does leave a dark charred edge. You can leave it as is, or if you prefer, you can easily sand the edges to remove the charring. Birch plywood is more expensive than Baltic birch, and may only be warranted for the highest-quality finished wood surfaces.
The outer veneers on birch plywood are quite thin, typically 0.010-0.020in (0.25-0.50mm) and the inner layers of veneer relatively thick, typically 0.125-0.150in (3mm+). This plywood comes in nominal fractional inch thicknesses (1/8, 1/4, and so forth), but the thickness is always about 1/32in less than the nominal. Typically, both 1/8in and 1/4in birch plywood have three inner softwood layers and two thin outer birch veneers. Of course, MakerStock provides pre-cut birch plywood panels in the right sizes for the laser cutter, or to a size convenient for your project.
Like all plywood, the faces are graded for quality. Our birch ply is B4, which means the better side is grade B and the worse side is grade 4 (the back side for this type of plywood is graded 1-5, with 1 best). The B side is beautiful, with no knots or patches. The back side is usually very nice, but will usually have a few pin knots, some color variation, and perhaps a “football” patch. Typically you design your object such that the “4” face is on the back side or inside of an assembled object.
You can finish birch ply like any hardwood. We like the wipe-on Minwax polyurethane. Sand first, and then apply thin coats, with light sanding between applications.
Birch plywood is essentially the same density as softwood plywood, because the veneer core is mostly softwood. Density runs about 570 kg/m3 or 0.021 lb/in3.