Veneer is obtained either by "peeling" the trunk of a tree or by slicing large rectangular blocks of wood known as flitches. The appearance of the grain and figure in wood comes from slicing through the growth rings of a tree and depends upon the angle at which the wood is sliced. There are three main types of veneer-making equipment used commercially:
A rotary lathe in which the wood is turned against a very sharp blade and peeled off in one continuous or semi-continuous roll. Rotary-cut veneer is mainly used for plywood, as the appearance is not desirable because the veneer is cut concentric to the growth rings.
A slicing machine in which the flitch or piece of log is raised and lowered against the blade and slices of the log are made. This yields veneer that looks like sawn pieces of wood, cut across the growth rings; such veneer is referred to as "crown cut".
A half-round lathe in which the log or piece of log can be turned and moved in such a way as to expose the most interesting parts of the grain, creating a more textured feel and appearance; such veneer is commonly referred to as "rift cut." [2]
Each slicing processes gives a very distinctive type of grain, depending upon the tree species. In any of the veneer-slicing methods, when the veneer is sliced, a distortion of the grain occurs. As it hits the wood, the knife blade creates a "loose" side where the cells have been opened up by the blade, and a "tight" side.
North American softwood dimensional lumber sizes
Nominal Actual Nominal Actual Nominal Actual Nominal Actual Nominal Actual
inches inches mm inches inches mm inches inches mm inches inches mm inches inches mm
1 × 2 3⁄4 × 1 1⁄2 19 × 38 2 × 2 1 1⁄2 × 1 1⁄2 38 × 38
1 × 3 3⁄4 × 2 1⁄2 19 × 64 2 × 3 1 1⁄2 × 2 1⁄2 38 × 64
1 × 4 3⁄4 × 3 1⁄2 19 × 89 2 × 4 1 1⁄2 × 3 1⁄2 38 × 89 4 × 4 3 1⁄2 × 3 1⁄2 89 × 89
1 × 5 3⁄4 × 4 1⁄2 19 × 114
1 × 6 3⁄4 × 5 1⁄2 19 × 140 2 × 6 1 1⁄2 × 5 1⁄2 38 × 140 4 × 6 3 1⁄2 × 5 1⁄2 89 × 140 6 × 6 5 1⁄2 × 5 1⁄2 140 × 140
1 × 8 3⁄4 × 7 1⁄4 19 × 184 2 × 8 1 1⁄2 × 7 1⁄4 38 × 184 4 × 8 3 1⁄2 × 7 1⁄4 89 × 184 8 × 8 7 1⁄2 × 7 1⁄2 191 × 191
1 × 10 3⁄4 × 9 1⁄4 19 × 235 2 × 10 1 1⁄2 × 9 1⁄4 38 × 235
1 × 12 3⁄4 × 11 1⁄4 19 × 286 2 × 12 1 1⁄2 × 11 1⁄4 38 × 286
In North America, market practices for dimensional lumber made from hardwoods[a] varies significantly from the regularized standardized 'dimension lumber' sizes used for sales and specification of softwoods – hardwood boards are often sold totally rough cut,[b] or machine planed only on the two (broader) face sides. When Hardwood Boards are also supplied with planed faces, it is usually both by random widths of a specified thickness (normally matching milling of softwood dimensional lumbers) and somewhat random lengths. But besides those older (traditional and normal) situations, in recent years some product lines have been widened to also market boards in standard stock sizes; these usually retail in big box stores and using only a relatively small set of specified lengths;[c] in all cases hardwoods are sold to the consumer by the board-foot (144 cubic inches or 2,360 cubic centimetres), whereas that measure is not used for softwoods at the retailer (to the cognizance of the buyer).[d]
North American hardwood dimensional lumber sizes
Nominal (rough-sawn size) S1S (surfaced on one side) S2S (surfaced on two sides)
1⁄2 in 3⁄8 in (9.5 mm) 5⁄16 in (7.9 mm)
5⁄8 in 1⁄2 in (13 mm) 7⁄16 in (11 mm)
3⁄4 in 5⁄8 in (16 mm) 9⁄16 in (14 mm)
1 in or 4⁄4 in 7⁄8 in (22 mm) 13⁄16 in (21 mm)
1 1⁄4 in or 5⁄4 in 1 1⁄8 in (29 mm) 1 1⁄16 in (27 mm)
1 1⁄2 in or 6⁄4 in 1 3⁄8 in (35 mm) 1 5⁄16 in (33 mm)
2 in or 8⁄4 in 1 13⁄16 in (46 mm) 1 3⁄4 inches (44 mm)
3 in or 12⁄4 in 2 13⁄16 in (71 mm) 2 3⁄4 in (70 mm)
4 in or 16⁄4 in 3 13⁄16 in (97 mm) 3 3⁄4 in (95 mm)
Also in North America, hardwood lumber is commonly sold in a "quarter" system, when referring to thickness; 4/4 (four quarter) refers to a 1-inch-thick (25 mm) board, 8/4 (eight quarter) is a 2-inch-thick (51 mm) board, etc. This "quarter" system is rarely used for softwood lumber; although softwood decking is sometimes sold as 5/4, even though it is actually one-inch thick (from milling 1/8th inch off each side in a motorized planing step of production). The "quarter" system of reference is a traditional (cultural) North American lumber industry nomenclature used specifically to indicate the thickness of rough sawn hardwood lumber.