WOOD SCIENCE
Parts of a Tree Pith Heartwood Sapwood Cambium Bark
Lumber Surfaces
Growth Rings One complete growth ring equals one year of growth. One growth ring is made up of earlywood (spingwood) and latewood (summerwood). Earlywood is the part of a growth ring that is soft and light in color. Latewood is the part of a growth ring that is hard and dark in color.
Lumber Sawing Plain Sawed Quarter Sawed Boards are cut tangent to the annual rings. Yields wider boards. Most common. Quarter Sawed Yields narrower boards. Has the most figured lumber.
Hardwoods and Softwoods Hardwoods are broad leaf trees and are known as deciduous. Hardwoods. Oak Maple Walnut Cherry Mahogany Ash Birch Softwoods are needle and cone-bearing trees and are known as coniferous. Softwoods. Pine Spruce Fir Cedar Redwood
Softwoods Samples
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Hardwood Samples
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Exotic Hardwoods
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Expansion vs Contraction Moisture causes wood to expand or swell. Dryness causes wood to contract or shrink. Repeated exposure to dry and moist conditions causes defects, such as, warping, splitting, checking, and winding. Climate conditions must be considered when designing a project. Most lumber today has been kiln dried. This lumber has been placed in a lumber kiln and specially, treated with steam, heat, and air, to greatly, reduce the drying time and the amount of defective material.
Lumber Grading Hardwoods are graded by their poorest face. This insures that both faces of the lumber are of furniture quality. Softwoods are graded by their best face. Hardwoods are usually, selected for a project due to their excellent visual qualities and their ability to withstand wear. Softwoods are chosen usually, for heavy construction projects because they have very good structural qualities.
Common Woodworking Abbreviations KD = kiln dried AD = air dried Clear = free of knots and defects Highest grade lumber. Used by mills to make trim. FAS = first and seconds High grade lumber used for cabinet and furniture making Sel+Btr = select & better Not found often. Grade slightly below FAS. #1 com = #1 common Lower grade of lumber, but if ordered in quantity there is a lot of useable stock. #2 com = #2 common Grade below #2 COM. SHOP = shop grade Lowest grade of lumber. Can be graded low because length is too short, which means the lumber could be high quality. RWL = random widths and lengths S2S = surfaced on 2 sides S4S = surfaced on 4 sides RGH = rough