smooth beach rocks
borax (in the UK, you can order Borax online here)
hot water
jars or plastic containers
spoon
liquid watercolours
medicine droppers or small paintbrushes
First we filled a jar with 3 cups of very hot tap water. Then we added 9 tablespoons of borax. We stirred and stirred until the borax had dissolved. Then, using a spoon, we lowered our rock into the jar of borax-water, and left it on the counter to do its thing.