After literally hundreds of years of building a reputation as a purveyor of high-quality solid hardwoods, several years ago J. Gibson McIlvain ventured into the world of hardwood plywood. A popular manufactured lumber product, plywood can greatly vary in quality. After hearing many customers complain of cheaply made, unstable ply, we decided to add only the most stable materials to our inventory. Since stability is the very reason a builder chooses plywood over solid wood for certain applications, that factor is clearly significant. The most significant feature of plywood, regarding stability, is its core. And the thinner the face veneer, the more significant the core.
The most common material comprising plywood core, veneer core is known for having the best capacity for holding screws. Typically, thin veneers ranging from 2 to 6.5 mm thick are laid out with grain running in alternating directions, providing great stability. As you might guess, the more layers which are used, the more stable the product becomes. Because of the inevitable gaps between layers of veneer, the number and sizes of those gaps help determine the sheet’s grade. Because veneer species are plentiful, veneer core plywood is the most well-known type. Within the realm of veneer-core ply, there are many options for veneer species. Of course, the manufacturing mill’s location will limit the potential species that can be used. Common species include Douglas Fir, Poplar, Aspen, Birch and Maple, with the latter two providing the greatest amount of stability.
Although not as popular as veneer core, lumber core uses thick strips of hardwood, often Basswood. Those strips are glued into a larger panel and then face veneered. Only the highest grade lumber is used for the core, preventing significant voids and inconsistencies. Although the most expensive type of core, lumber core is ideal for applications in which edges cannot be hidden, and routed edge treatments are required. Because of the expense involved, few manufacturers venture into this type of plywood.
MDF and Particle Board Core
Although they do create two distinct types of finished products, MDF and particle board cores are similar in that they are both composite substances. Created from wood particles glued together to form a substrate, both MDF and particle board can provide a dimensionally uniform, flat surface onto which face veneer can be applied. More stable than solid wood core plywood, these sheets are much heavier than other types of plywood. Particle board is lighter than MDF because it uses larger pieces of wood; however, edges can splinter easily and lack the strength of MDF. MDF is basically made of dust-sized particles of wood, creating a millable, stable substrate with strong and smooth edges. Both cores have traditionally lead to problems with holding screws, but with specialty screws that have wider threads, they can overcome that problem.
J. Gibson McIlvain currently carries high quality MDF and veneer core plywood. Our most popular veneer species are Birch and Fir.