Why it pays to buy good plywood

Is it your imagination or is good plywood getting harder to find? Not if you shop smartly. Armed with these buying tips, you'll sort the stack like a pro to pick the perfect plywood for your next project.

When evaluating a sheet of plywood, start by looking at its edge. Thin veneers of wood, glued and pressed with crossing grain directions—transform humble core woods into sheets that are wider, flatter, and more dimensionally stable than anything found in nature. But modern plywood manufacturing, especially overseas, has shifted from birch-only cores to other often-inferior woods at the expense of core quality and stability.

When examining plywood, ask yourself: Are the layers straight, of a consistent thickness, and free of large voids? Irregularities in the core veneers can telegraph through to the thin face veneer and broadcast themselves during sanding and finishing.

Sight along the edge to check the sheet's straightness. A bow indicates unevenly dried core material that only warps more, as cutting the sheet releases internal tension.

Although the 13-ply construction of the previous slide sample is more forgiving of the overlapping core layers and voids than standard 7-ply sheets, shown here, the defects in this sheet are severe enough to telegraph as an undulating face, especially with a glossy finish. The superthin face veneers, around ¹⁄₅₀ ", would make sand-through difficult to avoid, and cross-cut splintering a near certainty. In comparison, we'd have no such reservations with the second sheet.

One alternative to traditional veneer-core plywood, combination-core plywood, eliminates worries about inconsistency and flatness by retaining the three center veneer plies and replacing the outer plies with medium density fiberboard (MDF). The MDF provides a smooth and flat surface immediately below the veneer faces.

As strong as plywood must be on the inside, it must also be pretty on the outside. Plywood grading, as much aesthetic art as science, designates one face as the front and one as the back; grading is on separate scales. Most domestic hardwood plywood manufacturers use the Hardwood Plywood and Veneer Association's (HPVA) voluntary standards for grading. The front face, judged for uniformity of color and consistency of grain, receives an AA, A, B, C, D, or E grade; see chart. For the back face, the grade is designated 1, 2, 3, or 4, with respectively less-restrictive allowances for defects and repairs.

Much like hardwood, hardwood plywood comes in plain-sliced, riftsawn, and quarter cuts. But unlike hardwood, face veneer can also be rotary-sliced, a method in which the veneer is peeled off spinning logs, like a roll of toilet paper. This produces an unnatural, wide, swooping grain pattern, as shown in photo, but generally yields the most veneer of the cutting methods, producing the least-expensive sheet.

For non-rotary-cut face veneers, look for the glue-up pattern where the face veneers are matched on the plywood core, as you might match veneers on your own project.

This C3-graded red-oak plywood was sold in the home center as "cabinet-" or "furniture-grade" plywood. At a quick glance, the rotary-cut faces look decent. But close inspection of the edges reveals uneven core veneers, large voids, and a distinct curl.

Manufacturers of A1-graded plywood don't skimp on the core materials. This hardwood-store-bought sheet has consistently even core veneers and a plainsawn, slip-matched face. The price, 50% costlier than C3, is justified for projects that display both faces.

Combination-core plywoods combine the best qualities of veneer-core plywood (rigidity and screw-holding power) with MDF-core products (surface flatness and dimensional consistency) into a furniture-friendly sheet.

Unless you need ultra-high-end (and high-cost) AA-graded hardwood plywood, stick with A1, A2, B1, or B2 for furniture or cabinets with visible faces. Rarely will a hardwood plywood dealer carry more than a handful of grades. Rather, at a well-stocked dealer, you'll find a selection consisting of a good-on-two-sides (G2S) grade, such as A1, alongside a lesser grade, such as B2, often in multiple species. A good-on-one-side (G1S) grade, like A4, might also be on hand, but retailers often only stock this in ¹⁄₄ " for case backs.