Thanks Bruce. Along with being biodegradible, the idea of spraying it on, then pressure washing it off appeals to me. Especially on the Airstream, because I want to avoid using metal scrapers on the aluminum.To use this method, I would have to use something bio-degradable, because it would be likely some of the residue may get into the soil, though I would try to contain it as best I could. Mostly I wanted to hear from someone who had used it so I had an idea of how effective it was. I assume you still need to take the same precautions, ie. rubber gloves, goggles, etc.