What are medullary rays?

Medullary rays are, in short, growth cells that typically grow in oak, extending radially from the center of the trunk (pith) and vertically outwards towards the bark side.

They are characterized by their light and patterned appearance, which becomes particularly prominent after the oak has been sanded and oiled.

Medullary rays are actually 'growth rings' in the form of plant cells that grow with the tree, and they have a shimmering color that appears somewhat silvery depending on the direction from which they are viewed.

In addition to oak, medullary rays are also found in conifers and hardwoods, but they are most characteristic in oak.

Why are medullary rays seen in oak?

The reason they are visible in many oak products is due to the way the wood is cut.

Image from thefurnituremarket.co.uk

There are basically two ways to cut oak:

• Plain sawn
• Quarter sawn

Plain sawn means that slices of wood are cut lengthwise. Here, the slices will naturally become wider the closer one gets to the center. This is the cheapest, fastest, and most common way to cut wood.

Quarter sawn means that the trunk is divided into 4 quarters – like a layer cake. Then, slices of wood are cut across the quartered trunk. The slices are therefore not as wide, and the process itself is somewhat more time-consuming than plain sawing.

At the same time, the direction of the growth rings means that quarter-sawn wood will typically have more medullary rays on the surface and be more durable than plain-sawn wood.

Are medullary rays a sign of disease?

No – quite the opposite. Medullary rays are the nerve of the tree's growth, and as mentioned above regarding quarter-sawing, it is a sign of healthy and more durable wood that has required an elaborate process to cut.

Medullary rays are therefore completely natural and a sign that your oak products are made from quality wood. At the same time, medullary rays give oak a characteristic and unique expression that you won't find in the same way in other wood products.

Both the floating shelves, wall clocks, hooks, toilet signs, and door stoppers designed by PureTime are made from quarter-sawn, solid oak.

Image of an example of a Saksild wall clock with medullary rays