I read a lengthy article on how the edge of a straight razor reacts to being used. It seems that microscopically, the honed edge of the blade looks like a comb

I read a lengthy article on how the edge of a straight razor reacts to being used. It seems that microscopically, the honed edge of the blade looks like a comb of teeth. When you shave, these teeth fold over. Stropping apparently straightens out the folded edge. Eventually these teeth break off, and the edge has to be remade. That can be done with a few strokes on a coticule, every 6 months or so. The authors apparently experimented on stainless steel blades; stright razors are made from carbon steel, which doubtless has a different microcrystalline structure. [I know, the article's about disposable razors]