This chalk actually has a special coating that prevents that from happening. This post from a while ago explains why "Mathematicians Are Hoarding a Type of Jap

This chalk actually has a special coating that prevents that from happening. This post from a while ago explains why "Mathematicians Are Hoarding a Type of Japanese Chalk" https://news.ycombinator.com/item?id=9723202 https://news.ycombinator.com/item?id=9723202