Anyone who has seen a chalk drawing knows that when the artist finishes his picture, he turns on a black light and a previously "invisible" picture appears. But how does the artist get the picture up there? The "secret" is invisible fluorescent chalk, and in today's video tip, STL chalk artist Jim Pence demonstrates how invisible fluorescent chalk works.

By James H. Pence

If you are going to be a chalk artist, obviously you will need the right kind of chalk and paper. Unfortunately you can’t just run out to your local art supply store and buy a set. In fact, most art supply houses not only don’t carry the right kind of chalk, most of them haven’t even heard of it. The chalk you need is called “lecturer’s chalk”, but if you go into your local arts and crafts store and ask for it, they’ll look at you as though you told them you just flew in from Mars.