Ok, so I did a little experiment a couple weeks back. I've never treated the underside of my deck with anything to assist with scraping. I usually scrape it every couple weeks and would collect about 25# of grass out of the deck. After the last scraping, I decided to give the FF a shot. I've read mixed reviews about how well this works but decided it wouldn't hurt to give it a go. I scraped (Didn't wash it at all) and sprayed the deck liberally. Reinstalled the blades and forgot about it. Today (about 2 weeks since the treatment) I decided to jack it up and see what it looked like. Upon inspection, I was literally dumbfounded. 90% of the deck was absolutely spotless. No joke, I mean where the paint is worn off there is bare metal and it was shiny. I'm still shocked at these results. Even better is the fact that I know there was still some grass left on the deck in areas where it is now completely clean. I think by leaving it to sit over night it loosened the dirt and once the blades started spinning the remaining grass just dislodged and was removed. Today I would guess I scraped (and quite easily I may add) all of 2# of grass off the deck. It took me 5 minutes to completely clean the underside of the deck. I'm sold on this method. My question to the others that didn't achieve these results, how long did you wait before you started using the mower? I know that the properties in FF are supposed to adhere to the metal so I'm wondering if the secret is letting it sit? Just thought I'd post up my findings. Looks like I'll be ordering up a gallon of this as it would be easier to use a paint brush and just soak the bottom of the deck Love this stuff!