Lumber production and Types

Objectives To understand lumber production To understand the different types of lumber products

Lumber Production and Processing After trees are cut down they are transported to the sawmill. The logs are soaked to prevent checking, cracking, and warping. Logs are either plain-sawed or quarter-sawed.

Plain-Sawing Plain sawing: Cutting the log on a tangent to the growth rings Is faster with less waste resulting in lower cost lumber. Produces a flat or slash-grained lumber that is used for most buildings.

Quarter-Sawed Lumber Quarter sawing: Cutting the log perpendicular to the growth rings Results in lumber less likely to warp, shrink, and swell. Since quarter-sawed edge or vertical grained boards have a prettier grain, they are often used to make furniture.

Drying Lumber Seasoning: Process of drying lumber to the point where it is ready to use. Green lumber: Freshly cut lumber with 20 percent or more moisture. Air drying takes from one to three months and typically reduces moisture content to 15 percent.

Drying Lumber Kiln-dried lumber uses a large oven or kiln to dry the lumber to 6 to 12 percent moisture. Starting with high steam and low heat the kiln gradually adjusts to low steam and high heat to remove moisture without creating cracks in the lumber.

Dried and Planed Lumber Can be processed into a variety of wood products such as: Beveled siding, Tongue-and-groove flooring, Trim, Molding, Etc..

Plywood: Wood product made of a series of plies or layers (3, 5, or 7) glued together to form a 4×8 sheet. By gluing layers so that the grain runs in opposite directions the strength is maximized.

Particle Board 4×8 sheet made by gluing wood chips, splinter, and sawdust together. Because it is hard and brittle, it is used under countertops and in some furniture. it needs to be cut with a carbide-tipped blade Warps quickly when it gets wet.

Waferboard Also known as OSB board and chip board Made by gluing wood chips to form 4×8 sheets. Since it is cheaper and more water resistant, wafer board is replacing plywood as roof sheathing and subflooring.

Hardboard Made by gluing wood fibers into sheets. Since it is hard and brittle, it should be cut with a carbide-tipped blade and it does not hold nails well. May be used as tabletops or shaped in long boards to use as siding.

Paneling 1/8 or ¼ inch sheet of wood or hardboard with a wood grain surface. Cheap paneling may be hardboard with wood grain contact paper on the surface.

Veneer Thin layer of material that is glued to an inferior quality material. While high quality furniture is generally solid wood, low cost furniture is often particle board with a veneer wood grain surface layer.