I recently replaced the Koverall fabric covering for my tympan with paper, shrunken into place. The paper seems much better, tough, very taut and flat, like a drum head. In addition, tape holds to the paper better than it does to the fabric.
I used the Permalin paper recommended by Rummonds. You can get reasonably small quantities from Steve Pratt at Pratt Wagon Works; Cove Fort; Beaver, Utah 84713. Phone/Fax: (435) 438-1024.