I originally found out about Corte Clean from the manufacturer of my deck. One board was turning black and moldy, while others were not? The representative from TimberTech came out and informed me that some of the boards appeared to be treated to prevent mold, while others were not and that Corte Clean is the best product. The black mold no longer comes back. I use to buy Corte Clean from my local lumber retailer. They stopped carrying it, so I started buying it directly from its website in 2010. Nothing works like Corte Clean, as I have tried many other products. While Corte Clean may seem expensive, you get what you pay for. It gets rid of grease and oil from the barbecue and other stains too. It is not labor intensive, give it a chance to work and a little brushing. I use it in the spring and fall to keep the keck clean, however, last year I couldn’t clean the deck and a little green mold has returned. I live on the ocean in New Jersey, so I didn’t want to use a cleaner that was corrosive to the metal decking hardware. My deck looks like new once cleaned with Corte Clean.