Tenter Frame

A tenter frame is a rectangular wooden frame fitted along its edges with rows of small hooks, called tenterhooks, used to stretch a piece of newly fulled woolen cloth taut while it dries, so the cloth dries flat, square and at its intended finished dimensions rather than shrinking and distorting unevenly. The weaver or finisher fastened the cloth's two selvedge edges onto the hooks running along the frame's long sides, drawing the fabric out to its full width and length before leaving it to dry in the open air or, in later factory versions, in a heated drying room. Tenter frames have been used in woolen cloth finishing since at least the fourteenth century, and the phrase to be on tenterhooks, meaning to be held in uncomfortable suspense, derives directly from the sight of cloth stretched taut on the frame's hooks; industrialized versions of the same stretching-and-drying principle, now usually called stenters, remain a standard finishing step in textile mills.