We have a cedar home covered with cedar 1/2 log siding. It badly needs restoration. My research so far has shown two types of finishes: Film Formers and Penetrating Finishes. Film formers include many alkyds, latex/acrilics and varnish resins in solvent or water based finishes. Penetrating finishes are oil or water based products which typically contain a drying oil resin in a stain. Also natural oils are in this class along with some newer water based systems using synthetic oils and resins.