Answer: buckram

AnswerCrossword Clue
BUCKRAMCloth used for bookbinding.
BUCKRAMBookbinder's material.
BUCKRAMStiff fabric for lining
BUCKRAMInterlining stiffener
BUCKRAMBookbinder's fabric
buckramto stiffen (to make stiff (not easily bent))
buckramstiff cotton fabric