Water Brush

" For those who don't know, a water brush or waterbrush (some makers use two words while others combine them into one) has a soft plastic barrel which contains water. When you squeeze the barrel, water enters the bristles, thus eliminating the need for a separate water container. It also makes cleaning the brush between colors a breeze. These are great for watercolor sketching on location. All you need is a waterbrush, a small set of half pan watercolors and a sketchbook, plus some tissue paper or a rag. No more water bottle and cup. If you use a small sketchbook, your entire set up will fit in a pocket. " writes Russel Stutler. Read on about this great utility here.