I ended up out front trimming a maple tree. It had moss all over it and lots of dead branches - some fairly large. I figured it was a goner, and been thinking of cutting it down, but the wife wanted me to try to save it. So I cleaned out anything dead I could reach and a pruned few others. Then I decided to try the pressure washer on the moss. Worked great (other than me getting covered in the crap flying everywhere)and didn't damage the bark. Looks a lot better now. :thumbsup: