Impossible to fold, of course.
"All hail Bertha Berman, who on this (actually yesterday) day in history filed a patent for the fitted sheet. "Berman, an African-American from Forest Hills, N.Y., invented the fitted bedsheet, patented on this day in 1959. Her design featured a detachable band that encircled the sides of the mattress, keeping it in place and allowing the sheet to be easily removed for washing. This eliminated the need for flat-sheet corner tucks, the so-called hospital corners that were as hard to master as they were unreliable. Berman’s bedsheet was an improvement, and other designs followed, but Alberta’s Gisele Jubinville wanted a better one. In 1992, she patented the design we know today – a sheet with deep pockets on the corners that wrap under the mattress. “I was fed up with fitted bed sheets that didn’t stay on the mattress,” Jubinville said by phone. “I didn’t know how to sew, [but] I’m about solving a problem.” - Globe and Mail.
