Hi Pat. There's a specially treated, very thick sponge you can try. I saw it at a local paint/wallpaper store, but have not tried it personally. It's supposed to remove smoke film and soot (as in after a fire). Otherwise, a good cleaning with something like Murphy's oil soap might just do the trick, before you tackle sanding, etc. TSP is a great cleaner, but I'm not sure if you can still purchase it (it contained phosphates, I think, and therefore might not be available anymore). I used it all over our house when we first moved in 5 yrs ago. If used in strong enough concentration with a very fine steel wool pad, it acts as a mild wood stripper. It might get that top layer of smoke film off without actually sanding the cedar. Perhaps the others can offer something, too?