How to Make Sidewalk Chalk Paint:
Mix together the water and cornstarch, and stir until the cornstarch dissolves. Our chalk paint recipe generally calls for a 1:1 ratio of cornstarch and water, but since we were painting on the sidewalk instead of paper, I incorporated just a bit more water and found that we liked it even better. We were able to paint longer brushstrokes without needing to reload the paintbrush with paint, which is always great for younger kids. Divide the paint mixture into the wells of a muffin tin or similar painting tray, and add food coloring to achieve the desired colors – note that the colors will dry much lighter on the sidewalk than they appear in the tin!
When the kids were done painting with the paintbrushes, they decided to paint their hands and feet and make hand/footprints on the sidewalk. They had a blast with it! The paint washes off their skin easily with soap and water, and we didn’t run into any problems with the food coloring staining their skin or the concrete.