I did a some little studies in graphite and transparent white gouache:
I haven't worked like this before (for my opaque studies, see my Sloths and Statues), but I've enjoyed it enough to plan for a future piece using this method. You can water the gouache down to a very thin consistency and still get even washes (this may not be so easy on a larger scale). It's also easy to go back and lift the gouache to get some soft edges. The paper I'm working on is a recycled paper version of the manila folder available at most office supply stores.
And here are the pieces I worked from for the studies:
The Garden Walk. Success. June 1904
Men with Golf Clubs. Arrow Collar Advertisement. 1914