Start with two parts soap (we used 1 Tbsp.)
Then add one part paint (we used 1/2 Tbsp.)
Mix it together and you're good to go
We were a little gun shy at first so we started with "washable finger paints". Once it was clear that the paint would indeed come clean as promised, we moved on to the deeper hued "washable kids paints". When we were done, all it took was a wet towel to clean up our mess. This one is definitely going on the rainy day list!