We attempted two styles of chalk paint, with one significantly better than the other. Trial and error is the only way to get this right.
The first recipe called for a 50/50 mixture of cornstarch and water mixed together well.
Separate the mixture into cups and add coloring. What it creates is a nearly slime like texture. Not quite the best for painting.
Recipe 2 called for a 2:1 ratio of water to cornstarch. It already seemed more promising.
Though one was a little messier than the other, kiddos will love playing with both variations. Bonus, clean up was a breeze!