Medullary Rays Are Naturally Occurring in Oak Wood

Medullary rays are cellular structures found in the trunks of trees. In a cross section of a tree trunk, they are visible to the naked eye and appear as radiating lines from the center of the log, perpendicular to the growth rings. These medullary or pith rays are essential and serve as a link between pith (center) and cortex (periphery) of the live tree. They perform various functions like food storage and transport of food and water.

In a finished piece of furniture or countertop, medullary rays may appear as rays, silking, and pith flecks. Depending on where the board is cut on a ray, the appearance can be squiggly lines, straight lines, glowing lines, brush marks or flecks. While these rays functionally exist in all trees, they are especially noticeable in lumber from oak trees, like Appalachian Red Oak and White Oak found in some of our BB Co. products.

Medullary Rays in four tops
Medullary ray patterns

When boards are cut from an oak log, they are usually rip cut along the length (axis) of the log. This can be done in three ways: plain-sawing (most common), quarter-sawing (less common), or rift-sawing (rare). Most of the lumber we use is from plain-sawn boards and will result in wood grain in an oak countertop that will have a varietal appearance. The “normal” grain appearance may show up as “cathedral grain pattern” with high peaks in the grain, or a “long straight grain pattern.” However, in plain-sawn oak there will always exist some quarter-sawn lumber, too. (And even some rare rift-sawn grain may be present in plain-sawn boards.)

In quarter-sawn material, where the wood is cut into boards with the growth rings roughly perpendicular to the face of the board, the medullary rays are more abundant and conspicuous, often producing beautiful markings such as silver grain, medullary spots and pith flecks.

In some fine wood instruments, like high-end string instruments, the neck and fretboards may be made from quarter-sawn wood to help them remain stable throughout the life of the instrument and to keep the instrument in tune. In acoustic guitars, quarter-sawn wood is also often used for the sides which are steam-bent to produce the curves. Quarter-sawn is used in part for structural stability, but also for the appealing aesthetics of its wood pattern. Additionally, high-end cabinets may be made from quarter-sawn wood which puts the medullary rays on the face grain of the cabinets. It is also especially desirable for furniture and decorative paneling.

Medullary rays are going to exist in oak furniture. Unfortunately, we cannot predict how many, what kind, and how conspicuous they will be. Therefore, a consumer must make a thoughtful decision before they order an oak countertop, kitchen island top or table. Given the size of most countertops, medullary rays are very likely to appear in an oak top. For a smaller table, the likelihood of medullary rays probably goes down, but again, it really depends on the cut rails. If a piece of lumber has many medullary rays and is cut into rails for a table top, they are very likely to appear all in one table.

Just remember, medullary rays are naturally occurring in oak wood, not considered a defect, and the amount and type cannot be predicted, nor guaranteed. It is part of what makes wood so special. Every piece is truly different, and therefore, every countertop or piece of furniture is beautifully unique!