When I was a kid, a styptic pencil was the thing one would use to stop bleeding if you cut yourself shaving Note that I said one. I only shaved with an electric razor and gave that up 40 years ago. How does it work? Wikipedia offers a good explanation. As I remember, the one around the house when I was a kid was alum.

A few years ago someone cut themself and my wife said ground coffee could be used.