Identifying Chestnut Wood
People who salvage wood from old buildings in Tennessee usually wonder what species they have. In particular, folks often want to know if the wood could be American chestnut, because chestnut was a common species in the past but is now rare and the wood can be valuable.
The American chestnut tree (Castanea dentata) was widespread in the eastern United States before being wiped out by a blight (Cryphonectria parasitica) in the early 20 th century. Chestnut wood was widely used because it was abundant, has good wood-working properties and is naturally resistant to insects and fungi. Chestnut bark was also used as a source of tannin and the nuts were collected for food.
While chestnut was a common tree before the outbreak of the blight, oaks also have long been an important part of Tennessee forests. Both white and red oaks were used extensively for building materials in the past. In fact, oak is the most common species that I have seen in my experience with identifying wood from old buildings around the state.
Oak and chestnut samples are sometimes confused because both woods are “ring porous” Ring porous woods have bands of large cells parallel to the bark. If you examine a clean cut on the cross-section (end-grain) of a wood sample, you should be able to easily see the bands of earlywood pores that are characteristic of a ring porous wood. However, the wood of chestnut can be easily distinguished from that of the oaks by looking for the rays. Rays are groups of cells that extend from the pith to the bark. All species of trees have rays but they vary in size. In chestnut, the rays are small and cannot be seen with the naked eye. In the oaks, the rays are very wide and thus are readily visible to the naked eye.
Both oaks and chestnut are ring-porous – they have bands of large earlywood pores. In oak (left), the rays are clearly visible as light-colored lines oriented perpendicular to the growth rings. In chestnut (right), the rays are narrow and cannot be seen with the naked eye. Please note that the distinct color differences shown in these pictures are NOT a reliable way to distinguish these wood species.
Recycling old wood provides us with a useful link to the past and is a testament to the durability and functionality of wood from Tennessee 's abundant forests. Whether the lumber is oak, chestnut or another species, old wood is good!