I have half of my buffet drawers filled to the brim with kid craft supplies, and my boys love nothing more than to break them out and start making something. Recently we were all out of watercolors and they wanted to do "crafts." So we searched for a fingerpaint recipe, and found lots with dish soap added. It seemed a little strange to me, so I was happy that we finally found a recipe without it. I upped the heat in the recipe because it just wasn't thickening, and it worked. The colors are bright and beautiful!
1/2 cup cornstarch
1/2 tsp salt
3 tbsp sugar
2 cups cold water
food coloring (AmeriColor is my favorite)
Mix all ingredients except food coloring well with a whisk. Set over medium low heat.
Stir about 15- 20 minutes until thickened. If you are still wondering if it is thickened, it isn't. The mixture goes from water consistency to thickened very quickly towards the end of the time period, so don't worry - you will know.
Let cool. Distribute evenly into bowls or cups.
Add food coloring -- a little bit will do -- and mix with a spoon.
I suggest watercolor paper or some other thicker paper for this paint. It has a thick texture and is wonderful for sensory development. I even had fun painting!
Let the little ones paint away and once you're done, let it dry overnight.