Dealing with wood defects
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Wood Magazine

Dealing with wood defects

There's no such thing as the perfect board. But you can salvage a lot of "challenged" lumber using these tricks.



In woodworkers' dreams, all wood looks like the boards we see in cutting diagrams: flat and straight, with parallel edges and not a single knot or inconsistency. In reality, though, wood is far from perfect. Even the best grades often suffer from one or more of these common defects.

The best way to deal with lumber defects is, of course, to avoid questionable boards in the first place. But if a board has great grain, is the only one available that suits your needs, or carries a bargain price, don't reject it just because of a few problems. Use the following tricks to get the most from less-than-perfect lumber.


Bow Defect
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Bow: A board that rocks from
end to end when laid on one face.

Bow Defect

Solution: Salvage a bowed board by crosscutting it into shorter sections, matching the lengths of pieces to the curve of the board. Test setups or finishes with areas too bowed to produce flat stock. You may be able to create small parts, such as cleats or spacers, from the bowed pieces.


Crook Defect
crook defect
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Crook: A board that
rocks from end to
end when laid on
one edge.

Crook Defect

How you straighten the edge of a crooked board depends on the severity of the defect. If the crook is mild, run the concave edge over your jointer to straighten it. Use caution to prevent the leading end from catching on the outfeed table.

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To put a straight edge on
a crooked board, stick
it on a long, straight
carrier, such as a strip
of plywood (about
3/4 x 8 x 60"), using
double-faced tape.
Guide the carrier along
the tablesaw fence to rip
off one bad edge.

For boards with severe crook, options exist. You can crosscut the board into shorter pieces, then joint each. You also can rip off the crooked edge at the tablesaw using a long carrier board, as shown in Photo A, right. Or snap a straight line on the board, cut it with a handheld circular saw, then joint the edge smooth.


Cup Defect
cup defect
Enlarge Image
Cup: A board that rocks
from edge to edge
when laid on one face.

Cup Defect

Solution: Rip a wide, cupped board into narrow flat sections, as shown in Photo B, below right. Rip each piece slightly wider than you need, then re-rip or joint the edges square to the face. You even can glue these sections back together to create a wide board.

wood defects B
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Rip cupped boards with
the convex face against
the saw table. A scrap
clamped to the fence
guides the workpiece
and holds the portion
being cut flatly against
the table.

Transform mildly cupped lumber into flat, thinner boards. First, joint the concave face flat, then plane the other face parallel.


Twist Defect
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Twist: A board that rests
on opposite diagonal
corners when laid on
one face.

Twist Defect

Solution: A severely twisted board is difficult to save. You may salvage short pieces, though, by using a combination of the methods described on previous pages.


Checks, Shakes, and Knots
checks in wood
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Checks, shakes, and knots:
Checks are cracks across
the growth rings, and
shakes are cracks
between the rings. Knots
are remnants of branches.

Checks, Shakes, and Knots

Solution for checks and shakes: These cracks occur at the ends of boards, so you may simply cut off the bad areas. But don't be too hasty. Good narrow pieces often exist on either side of a check.

Shakes, because of their orientation, usually have to be cut off. Be leery of boards with excessive shake. This may be a result of the board simply being dropped on one end, but shakes also can be a sign of improper drying.

Solution for knots: If they're tightly held in the wood, knots usually pose just appearance problems. Use these boards in inconspicuous places where the knots won't show. Loose knots, on the other hand, may fall out or be pulled free by cutting bits and blades. Cut out and discard areas with loose knots.



Wood Magazine