When a Water Pic looses some of its uumph! I'm thrilled!! I use them to dye fabric and yarn or to paint with.
I just fill the "tank" with mixed dye, that I've put through a sieve, then spray on either dry or moistened fabric or yarn. To paint, I fill the "tank" with acrylic dyes that have been watered down and mixed well. It's great. You can really get some great pictures (on stretched canvas or old wood).
It comes out beautifully; with gorgeous striation, great lines of varied widths and fun blobs and "drips". You can make things look like rock or marble or wood.