A tool of curving stone.

I use a chisel when I curve a stone. A chisel made of iron. The tip of chisel is very strong metal. What is called " tungalloy", it is a compound metal of tungsten and cobalt. A cost of the chisels are about 2,500 yen. When I was Art University student , at first, I made tip of a chisel. It means that a chisel has not tip of tungalloy. I put tip into fire. And then I keep going to bake the tip. So tip get red color. Next I put tip into water in rapid. It makes getting hard of the tip that put rapid it to get cool. The tip is not harder than tungalloy, but every old people use these tips.