When a log is sawed lengthwise into boards,
Slash cutting is the easier, quicker, and less
each saw cut crosses the annual rings at an angle.
wasteful of the two methods. The surface knots that
appear in slash-cut lumber affect the strength of the
If the angle between the saw cut and the rings is 45°
lumber much less than the knots that appear in
or greater, the board has a vertical grain. If the
rift-cut lumber. However, if a log is sawed to
angle is less than 45°, the board has a flat grain. If
the log feeds through without turning, the first few
produce all slash-cut lumber, more boards will have
outside boards cut off will be flat-grained. The
knots than if the log were all rift cut.
b o a r d s cut from the center section will be
vertical-grained. The last few boards cut will be
Rift-cut lumber provides edge grain on both
flat-grained. By turning the log between saw cuts
faces. If hardwood is rift cut, it is quarter-sawed
(fig. 3-3), you can produce all vertical-grained or all
lumber. If softwood is rift cut, it is edge-grain
lumber. When an entire log is slash cut, several
boards near the center of the log will actually be rift
Vertical-grained wood resists wear better than
flat-grained wood of the same species. Most
flat-grained wood will take and hold a finish better
Getting as many edge-grained boards as possible
than most vertical-grained wood. Use the term
from a tree requires that the logs first be sawed into
texture to express the relative size of the pores
quarters (fig. 3-3). Then, each quarter is sawed into
(cells) and fibers as coarse or fine textured and even
planks by one of the four methods shown. The
or uneven textured.
method used depends on the intended use for the
lumber. Radial quarter sawing will yield lumber
that is stronger and will warp less than that gotten
by any other method of sawing. The disadvantages,
In a large lumber mill, logs are processed into
however, are that this method is more costly, takes
lumber with huge band saws and circular saws. The
longer, and is more wasteful of material.
two methods of sawing the logs are slash cutting and
rift cutting (fig. 3-4). Slash cutting is from a series
of parallel cuts. If hardwoods are cut, the process
is termed plain sawing. If softwoods are cut, the
Once lumber has been sawed, it must be
process is termed flat-grain sawing.
seasoned (dried). The purpose of seasoning is to
remove the moisture from the cells. Moisture
(water or sap) occurs in two separate forms--free
water and imbibed water. Free water is the
moisture the individual cells contain internally.
Imbibed water is the moisture contained by the cell
walls. During drying or seasoning, the free water
evaporates until a minimum remains. The amount
of moisture remaining is the fiber-saturation point.
Figure 3-4.--Slash cutting and rift cutting.
Figure 3-3.--Four methods of quarter sawing.