Popular Woodworking 2003-08 № 135, страница 55

The Language of Lumber

A

air-dried lumber: Wood that has been dried from its freshly cut state by stacking it (usually outside) with stickers between. Air-drying reduces the moisture content to about 12-15 percent. Wood for interior use needs to be dried further.

B

board foot: A piece of wood that is 1" thick x 12" wide x 12" long in the rough - or its cubic equivalent.

C

chatter mark: A defect caused when the board was surfaced at the mill and the knives mar the surface. cupped: A board with edges higher than its middle. The cup is always to the sap side of the board.

D

defect: An imperfection in the board that will change how it is graded (and its price). dimensional lumber: Lumber that is surfaced on all four sides (S4S) to specific thicknesses and widths: 1 x 4s, 2 x 8s, etc. Note that with this lumber the finished thickness and width are less than the stated size. For example, a 1 x 4 typically will measure ³/4" X 3V4".

E

end check: Separation of the wood fibers at the end of a board, almost always a result of drying.

F

flitch: When a log is sawn into veneer and the sheets are stacked in the same order as they came off the log. Good for bookmatching.

G

green lumber: Wood that has been freshly cut from the tree, typically with a moisture content of 60 percent or higher.

H

heartwood: The part of the tree between the pith (the very center)

and the sapwood (the whitish outer layer of wood).

honeycomb: A separation of the wood fibers inside the board during drying - it might not be evident from the face of the board.

K

kiln-drying: An artificial way to reduce the moisture content of wood using heat and forced air. knot: A circular woody mass in a board that occurs where a branch or twig attached to the tree.

L

lineal feet: A measurement of wood that's 12", regardless of the board's width or thickness - usually used to refer to mouldings.

M

mineral streak: A typically green or brown discoloration, which can be caused by an injury to the tree. moisture content: The percentage of a board's weight that is water.

P

pitch: A resinous, gummy substance typically found between the growth rings of softwoods. pith: The small and soft core of a tree that the wood grows around. It's undesirable for woodworking. plain (flat) sawn: A method of milling a log that results in the growth rings intersecting the face of the board at an angle less than 45°.

Q

quartersawn: A method of cutting a log at the mill that results in the growth rings intersecting the face of the board at more than 45°. Quartersawing wastes more wood and there is more effort. But quar-tersawn wood is more stable.

R

random widths & lengths: While softwoods and cabinet woods such as red oak and poplar can be found

These boles are waiting to be de-barked, milled and dried to become prime hardwood.

as dimensional lumber, many hardwoods cannot. These hardwoods are cut in different widths and lengths to get the best grade. rift sawn: A method of cutting a log that results in the growth rings intersecting the face of the board at an angle between 30° and 60°. More stable than plain-sawn wood; less stable than quartersawn. rough: A board as it comes from the sawmill; not surfaced or planed.

S

SLR1E: The acronym for "straight-line ripped one edge," meaning the board has one true edge. S2S: Planed on two faces; the edges are rough.

S3S: Planed on two faces and one edge; one edge is rough. S4S: Planed to a smooth finish on all four long edges of a board. sapwood: The lighter colored wood between the heartwood and bark - typically weaker than the heartwood.

shake: A split that occurs before the tree is cut - typically from the wind buffeting the tree. shorts: High-quality lumber that is less than 6' long. sound knot: A knot that is solid across the face of the board and shows no sign of decay. straight-line rip: A perfectly straight edge that is suitable for gluing.

surface check: A shallow separation of the wood fibers.

T

twist: Where the board has warped into a spiral.

W

wane: The presence of bark on the edge or corner of a piece of wood. warp: A general term for a distortion in a board where it twists or curves out of shape. worm holes: A void in the wood caused by burrowing insects (killed during kiln-drying).

Thanks to Paxton, The Wood Source for assistance with this glossary.

LUMBER IS MEASURED IN QUARTERS

For new woodworkers, one of the most confusing aspects of buying lumber is figuring out the terminology for thicknesses. Rough lumber (which has not been surfaced) is sold in "quarters." Each quarter represents V4" of thickness in its rough state. So four-quarter lumber (written as 4/4) is 1" thick in its rough state; 5/4 is 1V4" and so on. When the lumber is surfaced by the mill it loses thickness. That's why 4/4 lumber is ³/4" thick when it's surfaced. Here's a chart that you can use as a quick reference:

If you Rough Finished ask for thickness thickness

4/4 1" ³/4"

5/4 1¹/4" 1"

6/4 1¹/2" 1¹/4"

8/4 2" 1³/4"

10/4 2¹/2" 2¹/4"

12/4 3" 2³/4"

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