When lumber is sawn from the log, the annual rings (viewed from the end grain of the lumber) can be oriented so that they run generally from one edge of the lumber to the other edge (called flatsawn lumber) or so that the rings run from one face to the other (called quartersawn).
Sometimes quartersawn is reserved for lumber that has annual rings that are at an angle of 75 to 90 degrees to the face (viewed from the end grain). Riftsawn is used when the rings are 45 to 75 degrees. More often, quartersawn means 45 to 90 degrees. Another name for flatsawn is plainsawn and another name for quartersawn is vertical grain.
Differences in appearance
There are some significant differences in appearance and behavior between flatsawn and quartersawn lumber. Perhaps the most important difference is the surface appearance for species that have heavy grain, such as oak, hickory, pecan, elm, hackberry and sycamore.
With flatsawn lumber, the annual rings tend to make cathedral, "V" or oval shaped patterns on the lumber faces. With quartersawn, the annual rings tend to make long lines running along the length of the lumber.
As with many hardwoods, quartersawn lumber will have a grain pattern (short, small areas of contrasting grain patterns), called ray fleck or just fleck, that adds significantly to the appearance. Also, wavy and interlocked grain becomes more conspicuous with quartersawn lumber. Generally, we find that flatsawn grain patterns are more preferred in North American markets, while quartersawn grain patterns with ray fleck are more popular in Europe and the Orient.
When using flatsawn lumber, the knots, if any, tend to be circular or oval. With quartersawn, knots can be long and narrow, called spike knots, which can severely weaken the strength of lumber.
With softwoods, pitch or resin pockets are limited to small areas in a few pieces with flatsawn, but can extend over a larger surface area with quartersawn.
Differences in behavior
In general, a flatsawn piece of lumber will shrink twice as much in width when the MC changes than a quartersawn piece of the same species. Quartersawn is substantially more stable, especially with hardwoods and will hold paint better when there are large wood moisture changes. Flatsawn, however, shrinks about half as much as quartersawn in thickness.
Quartersawn lumber has much less cup during drying or when the MC changes in use than flatsawn. However, quartersawn lumber is often prone to side bend when drying.
Flatsawn lumber, especially with some pines, is prone to developing raised grain and grain separation after planing resulting in a washboard appearance. There is little risk of this machining defect in quartersawn lumber.
Flatsawn lumber is prone to surface checking and honeycomb in species like oak, which quartersawn lumber does not except in extreme conditions.
Quartersawn lumber has the white sapwood only on the edge of the lumber, allowing it to be easily cut off, while with flatsawn, sapwood can be evident in large portions of some piece of lumber.
Differences in price
Flatsawn lumber is more common in the North American marketplace, as it is easier to saw and has higher yields. When sawing quartersawn lumber, the yields of lumber from the log drop 15 percent or more, and sawing times may increase by 20 percent. Quartersawn is therefore more expensive lumber.
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