Plain mull is a very porous product resembling “cheesecloth” used to reinforce hinges for textbooks and edition binding.
Cloth Archives, Page 2 of 2
Bookbinding Mull
Medium Hard Linen Journal, Plain
Cloth Archives, Page 2 of 2
Suburban Mills, Inc.
14 Jun 1930 - Classified Advertising - Trove
Browse Products Columbia Finishing Mills
12 Oct 1940 - Advertising - Trove
Prairie Land Bin Sweeps Empty 105-foot-diameter Tanks in Eight