There are several makers of water-soluble pencils. This one is called a “Derwent Inktense/Ink Black” and it gives you a rich, intense black when blended with water.
I used a Kuretake brushpen to deliver the water. It has a hollow plastic handle that you can fill with water. I worked back and forth with the water and the pencil, adding lines over wet washes or washes over lines, working my way from lighter to darker washes.
I used another brushpen with colored ink for a few spots of color. These tools fit easily in a pocket, and they’re convenient if you happen to be in a museum or a classroom and you don’t want to break out a whole watercolor set.
My subject is Keith Gunderson, a dedicated plein air painter and teacher, whose website is called “Classic Realism.”