Allison, from Learn ~ Play ~ Imagine, came up with this idea for her boys one day to add a new dimension to their outdoor play. She explains that they like to make and play with sidewalk chalk paint often and so she added a little something extra to the recipe. Her usual recipe calls for water and cornstarch, but for this batch of rainbow paint she also added baking soda. The kids didn’t notice a difference while they were painting the sidewalks until Allison handed them a bottle of vinegar.
You can mix up your own batch of Erupting Rainbow Sidewalk Chalk Paint.