I'm thinking maybe I should use one of those on a job I have coming up. It's a cedar deck, about 40 x 20. The homeowner has powerwashed it himself, twice, over the past 4 years. He never used any solutions, and I don't think he sealed it, because the cedar looks *extremely* weatherworn for a 5-year old deck, much like Dale's close-up pic above, with deep grooves. The customer asked if it should be sanded first, but I never thought of a floor sander. That would certainly speed things up.