Plywood may be made from hardwoods, softwoods, or a combination of the two. Some common hardwoods include ash, maple, mahogany, oak, and teak. The most common softwood used to make plywood in the United States is Douglas fir, although several varieties of pine, cedar, spruce, and redwood are also used.The outer layers of plywood are known respectively as the face and the back. The face is the surface that is to be used or seen, while the back remains unused or hidden. The center layer is known as the core. There are two broad classes of plywood, each with its own grading system. One class is known as construction and industrial.The other class of plywood is known as hardwood and decorative.
SIZE: The most common dimension is 1.2 by 2.4 metres (3 ft 11 in × 7 ft 10 in) or the slightly larger imperial dimension of 4 feet × 8 feet.Facts about Plywood,
Each piece of lumber is visually or mechanically inspected and graded according to the amount of defects present. The grade is stamped on each piece, along with information about the moisture content, and a mill identification number. The lumber is then bundled according to the type of wood, grade, and moisture content. The number and location of these defects determines the grade of the lumber, and the purchaser must choose the grade that is appropriate for each specific application.Facts about Grade Stamping & Branding,
Lumber with a thicknesses of less than 2 in (5 cm) are classified as boards. Those with nominal thicknesses of 2 in (5 cm), but less than 5 in (13 cm) are classified as dimension.
Lumber with a thicknesses of 5 in (12.5 cm) and greater are classified as timbers. The nominal widths of these pieces vary from 2-16 in (5-40 cm) in 1 in (2.5 cm) increments.
Most rough-cut lumber pieces are dried and then finished, or surfaced, by running them through a planer to smooth all four sides.Facts between boards and timber,
The trees from, which lumber is produced are classified as hardwoods or softwoods.
Most hardwood trees have leaves, which they shed in the winter. Hardwood trees include oaks, maples, walnuts, cherries, and birches, but they also include balsa, which has one of the softest and lightest of all the woods.
Softwood trees, on the other hand, have needles instead of leaves. Softwood trees include pines, firs, hemlocks, spruces, and redwoods.Both hardwood and softwood lumber pieces are graded according to the number and size of defects in the wood.
Defects include knots, holes, pitch pockets, splits, and missing pieces on the edges or corners, called wanes. These defects primarily affect the appearance, but may also affect the strength of the piece. The higher grades are called select grades.Facts about hardwoods or softwoods,