I don't like wasting paint so when I'm working on a spread with excess I just find a page in this one and mash it down. With this page I took my make-shift palette (a sour cream container lid) and pressed it to the page. I sprayed it with water and used my brush to swirl it.
Art journalling is a pack rat's dream. You can even find ways to glue in your paint-y paper towels and scrap paper. I'm collecting a nice little pile...