The design of flat bed sheets changed sometime in the 1980s. Before then, flat bed sheet has selvages at the sides, while the top and the bottom were hemmed, with the top hem being wider and more decorative, just as they are now. This all changed sometime in the 1980s, when the sides began to be hemmed. Sometimes the bottom of the sheet would be a selvage, but sometimes there would be no selvage at all. I would like to learn more about the technological changes that occurred at that time.
My guess is that, prior to the change, fabric for each size of flat sheet was woven on a different loom, so that four looms were needed to produce twin, double, queen, and king size sheets. Then, beginning in the 80s, fabric for flat sheets began to be woven sideways and hemmed on the sides so that only one size of loom was needed. My guess would be that the newer looms are wider than even the king size looms, because even king size sheets seldom have selvages at the bottom, which would be the side as the cloth was being woven.
Can anyone help me with this puzzle? I have tried searching on the Internet, with poor results.