buckram is a stiff cotton (occasionally linen or horse hair) cloth with a loose weave, often muslin. the fabric is soaked in a sizing agent such as wheat starch paste, glue (such as pva glue), or pyroxylin (gelatinized nitrocellulose, developed around 1910), then dried. when rewetted or warmed, it can be shaped to create durable firm fabric for book covers, hats, and elements of clothing.