What do lumber grading numbers mean?
I saw some cherry for sale the other day advertised as 90/0. What exactly does that mean?
—John Mabe, Harrisonburg, Virginia
John, we tossed this one to Keith Stephens, owner of Woodworkers Source lumber supply. According to Keith, sawmills or lumber wholesalers normally use this number only when selling to lumber retailers. It is a measure, by percentage, of the minimum heartwood content on the face and back. So, 90/0 would be at least 90% heartwood on the face with no minimum for the back. 90/50 and 90/70 are not uncommon in the hardwood wholesale business, but as you might suspect, the higher the minimum heartwood content, the higher the price.
Because cherry sapwood is not technically considered a defect for hardwood grading purposes, wholesalers will often add this information in addition to the cherry's board grade—First and Seconds (FAS), Select and Better (SAB), No. 1 common, etc.—to further describe the product.