Tiny Bubbles: Homemade Bathtub Paint

Our recent arts and crafts activities have generally ended with us in the bathtub.  So mom figured why not just move the arts and crafts there?  We usually get to help mix up whatever concoction we are going to play with, but this time around I think mom just wanted to get us in the tub (aka somewhat confined) and she mixed these up herself.  We followed this recipe, but used Johnson & Johnson's Pure Cornstarch baby powder instead -- obviously because in our house only real cornstarch does the trick with diaper rash and, therefore, we are out of stock.  It worked just fine, but mom ended up adding about 6 tablespoons of the cornstarch powder (instead of the 4 tablespoons called for in the recipe).  Mom anticipated the inevitable dropping of the paint in the tub, but was pleasantly surprised to find that even when submerged under water, the paint sort of stayed inside the container and wasn't ruined (when retrieved relatively quickly).  Cornstarch - what a wacky thing.  I'd like to say that we played nicely for a while, but Kane's attempts at hoarding quickly led to paint in my eye and that was the end of that (even with California Baby bodywash, I was not tear free).  I know we'll be doing this again, because we both really liked it.  But perhaps during separate bath times.