Use soda or food grade pickling lime (CaO) rather than chalk because chalk is difficult to dissolve without sufficient acidity.
+1. I like baking soda for its ease and safety.
+2 - Unless you're starting with high-sodium water, baking soda is safe, simple and effective.
This is good info, I have been having a hell of a time getting those sticks of chalk to dissolve. I tried switching from the big sidewalk chalk to the little chalkboard sticks but those were even worse because they are more dense.
Pretty sure most of those sticks of drawing chalk are not actually the same thing as the powder you get at the hbs.
I think so, that's part of the joke.