Why is the razor used in barbershops made of canvas that feels smooth?

Razors need very sharp blades. A sharp razor not only has a small broken angle, but also has a thin and smooth blade surface, because it needs to touch soft skin when shaving and will not hurt. However, a knife for cutting hard things should not be like a razor, otherwise the blade will be damaged. With canvas grinding, both sides of the blade can be ground flat (the blade will be rough after several uses), because the canvas surface is rough in the cloth, which has greater friction, is much smoother and softer than the grinding wheel and whetstone, and is firm and not easy to break, so it is very suitable for grinding razors. If the razor blade is dull, it should be polished with a grinding wheel and oilstone first, and then with a fine emery cloth. Canvas is very close to fine emery cloth for polishing.