When I was a child in the 40s and 50s, my father used to take the double edged razor blade, press it against the inside of a drinking glass (long way up and down) and slide it left and right to sharpen the blade. I don’t know if this actually made them last longer, but he was a dedicated blade rubber. Does anyone know if this actually helped? I guess it would be an easy enough experiment to test out if you had two blades to work with.
I don’t think it would sharpen the blade, no.