how to get rid of tough stains that won't come off with normal washing... According to the super-helpful website, How To Clean Anything, a product called Bio-Wash does the best job on dirty outdoor furniture. Although it seems like something that cuts through months of outdoor grime would be especially toxic, according to Bio-Wash's website, their products are water-based, free of solvents, and environmentally friendly. Bio-Wash Simple Wash cleaner is available through Environmental Home Center for $11.99/gallon. We've never used Bio-Wash, and we're wondering if it really works as well as we've heard. Any first-hand reviews? For more tips on cleaning outdoor furniture, see this post. Photo: Bontempi Casa.