Solid American chestnut lumber from recently harvested trees hasn't been available since the chestnut blight devastated the species in the first half of the 20th century. Imported wood from Europe and Asia closely resembles American chestnut in tone. Chestnut closely matches both red and white oak in grain pattern and color, but it has distinguishing characteristics that are identifiable even in reclaimed lumber.
Look for sapwood. The outer ring of sapwood of the American chestnut tree shows a distinctive yellow color. White oak and red oak--the two American species most like chestnut--show sapwood of cream or white color. Sapwood often shows even in finished pieces, and always at the edges of boards.
Use a knife or chisel to dig down to the true color of old beams or planks. Reclaimed lumber may have steeped for years in an environment that stained the wood darker than natural. Chestnut's resistance to decay made it a favorite for railroad ties, barn floors and even bridges. Cut through the stained layer to judge the real color of the wood, which should be lighter and more amber than red oak.
Look for closed pores. White oak's pores fill when sapwood ages and becomes heartwood, while red oak and chestnut pores remain open.
Check the face of planks for distinctive quarter-sawn rays. These iridescent grain patterns distinctive to oaks show best when logs are cut perpendicular to the center. However, even when plain-sawn, some surfaces will show ray figures. Chestnut's coarse grain pattern most closely resembles red oak, but it shows no rays.
Identify beams by sawing off a short piece of end grain. Again, check for distinctive vertical rays (darker lines crossing the annual rings). Red oak and white oak have visible, widely spaced rays. Chestnut rays are closely spaced and not visible to the eye.