I'm posting another value study today for a painting you'll see soon. I have really grown to enjoy doing these thumbnail sketches as I prepare to paint. I use the Tombow Brush markers in different shades of gray. There is a wide brushlike end as well as a fine tip on the other end for details. I primarily use the brush end to fill in large shapes quickly and then I finish off with a few more detailed touches with the fine tip. This gives me a very good idea of whether the composition will work as a finished painting. If not, I'll try again using different shapes, a different format or a different value pattern.