Sen may be popular in Japan, but it is not yet widely used in the United States.

Sen’s natural growing range includes China and Sri Lanka, but it is most closely associated with Japan, where sen’s premiere veneer logs are reportedly found. In Japan, sen is used for a wide range of applications, including furniture, chests, interior joinery, paneling, construction, piano cases, baseball bats, carving and turnery.

Rick Banas, Interwood Forest Products Inc., Shelbyville, KY, said sen in the U.S. market is mostly available in quarter-cut veneer. “Occasionally you see it flat cut. Sen’s not a very popular wood in the U.S. market. It was used extensively in Europe in the ‘70s and ‘80s, primarily flat cut for furniture. In the U.S. market you would see it used for architectural projects and some furniture.”

Banas described sen as a light-colored wood with a fine grain and close growth rings. It sometimes has a dramatic figure. He once sold a pommele-figured sen log that was used for airplane interiors.

“You sometimes see a fiddleback figure in sen and that would be popular for architectural applications as well,” said Banas. However, Banas added, it is still not widely used in the United States.

Sen works well with both hand and machine tools. It takes a variety of stains and finishes well. Sen’s heartwood ranges from an almost white color to yellow to green-brown, usually with a straight grain and a somewhat coarse texture.

Author Albert Constantine Jr. writes in the book Know Your Woods, that sen grows in the mountainous districts of central Japan and is also known as castor Arabia. Sen is of medium hardness and weight and somewhat similar to ash in the United States.

Big in Japan

Sen is a very popular wood and veneer in Japan.

“Most of the supplies sold in the U.S. are from Japan,” said Banas. “The Japanese use sen in many applications, from furniture and cabinetmaking to more utilitarian items, including tool handles.”

Sen is often confused with another Japanese export, Japanese ash, also known as tamo. In some areas, Japanese ash and sen are used as trade names for the same species; however, Japanese ash (tamo) is from the species Fraxinus mandschurica of the Family Oleaceae, while sen is from the species Acanthopanax ricinifolius of the Family Araliaceae.

Sen weighs an average of 35 pounds per cubic foot to tamo’s 43 pounds per cubic foot. Both sen and tamo are used for similar applications, including furniture, cabinetry, agricultural handles and sporting equipment. Japanese ash differs from sen in that it has very good steam bending properties. In fact, ash trees around the world are known for their superior steam bending qualities.

In the book, Encyclopedia of Wood, ash is described as “supremely suited to steam bending, taking the least time of all in a steam kettle to be rendered supple. Once bent, it also keeps its shape reliably.”

Both sen and tamo are used as lumber, veneer and in plywood. Tamo’s range of interesting figures likely surpasses that of sen, especially the unique peanut figure and distinctive “leaf” figure.

Constantine writes that the figured tamo logs are especially sought-after, with the prize figure being known as peanut “because of the resemblance to this product.” Tamo is different from sen and most other woods in that half of the tree is figured and half of it is plain, according to Constantine.

Another difference between Japanese ash and sen is that Japanese ash, with an already low moisture content, dries quickly and well.

Users Take Care

Veneers – Fritz Kohl Handbook, describes sen as an “all-around” species in Japan, but in Europe it is used primarily in the veneer form in bedroom furniture and mass-produced panels. According to the Fritz Kohl Handbook, “It is only possible to import sen to Europe when debarked and as flitches, i.e. already sawn half logs.

The handbook states that the wood finishes well because of its straight grain, but due to fluting, sen veneer may buckle and need pressing. The wood is said to have an unpleasant acrid smell when freshly cut. Drying also can be tricky with sen. “Sen can be dried comparatively quickly, but shrinks strongly in the upper humidity range. Therefore, a slow drying schedule is necessary to minimize inner tension,” according to the Fritz Kohl Handbook.

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