2 weeks after applying DEFY, with rain almost every day, it appears that the product lives up to its advertisements. I did watch a YouTube video about applying the product with a bristle brush. It made it a bit more difficult than rolling it on, however if the mold spots do not reappear in the near future, then we will have success. And by reading some of the reviews on this site, I waited until the sun was off the deck to apply DEFY. The deck cleaner that I used was Corteclean, and it does the trick to neutralize the mold, before putting down any new product. I have not tried the DEFY cleaner yet.