In 2015, the owner of the Japanese company that made Hagoromo chalk decided to shutter his business due to health and other reasons. Once the news was released, world-renowned mathematicians, teachers, and artists began stockpiling the chalk, some purchasing lifetime supplies. Eventually, Hagoromo was bought by the South Korean company Uma-Jurushi, where they’ve started reproducing the chalk, with generally good but mixed results.
In many ways mathematics is like craftsmanship. In some ways, it’s like artistry. In some ways, it’s like science. But there’s a real high craft side to giving a beautiful lecture on a blackboard. Mathematicians admire this in each other and like teams, use the best tools for it.