Creatures of the Night
Some days ago I discovered the medium gouache and I love it! Gouache paints are opaque, but they are water soluble which means that brushes and palette can be easily cleaned.
I found a set of 12 tubes (Reeves) for a very reasonable prize and had to try them out. I only used red and blue in this painting, and got various purple colours mixed with them. You can mix them on the palette of course, but you can also blend them on the paper by going over them with a wet brush.
The interesting thing is that they look lighter when they are dry, so you have to take that into consideration when you apply the paint.