Nick,

Start here for mixing ratios, http://softwashsystems.com/page_mixology.htm

Then there is a post or two already here on cedar and wood soft washing, use the search button at the top of this page.

http://softwashsystems.activeboard.com/t46567454/cedar-shake-siding/

http://softwashsystems.activeboard.com/t47774279/cedar-shake-roof/

and more if you dig.

AC