Spring warped wood means that the board is flat width-wise but the length is curved much in the way that a river bends.
The term “warped” is a nonspecific term that denotes a misshapen board. The glossary from The Collins Complete Woodworker reads: “Any defect in lumber that deforms a board’s shape.” And while that may be an accurate definition, it is the term itself that is not useful.
Twist warped wood has curves in both the length and width, making it look similar to a propeller from the end.
By using the terms cup, bow, spring and twist, a woodworker can accurately describe the specific distortion of a board.This is much more useful information than “warped.” “Spring” or “sprung” board has local variations, the most common being a “crooked” board.
