TLDR: This stuff is great and 100% accomplished what I needed in what I think was a somewhat challenging use case. However, there was a bit of a learning curve for applying it properly.- The Project: Creating a vent for portable AC exhaust hose in a disgusting and ancient basement window.- The Process: First I removed the old and already completely shattered glass window from the window frame. I tried to chip out all of the old mortar or whatever it was that held the old glass window into the frame but some of the bits were impossible to remove. I knew I wanted to remove as much of that as possible so that the new panel that I put in place would sit flush and make for a better seal. This proved extremely difficult but I was eventually able to get the panel to fit into the metal framing fairly well.Once the vent panel was in place I started with the foam. There was a learning curve.I started from the outside of the house. Applying the foam into the gap at the bottom went perfectly fine. Then things got ugly. When I first tried to seal along the right side, going up and down vertically, the foam just sort of rolled off the front of the vent panel. It made a mess and was turning what had been a surprisingly tidy and semi-professional looking result into a huge mess. And more importantly, the seal was clearly not made. There was no insulation along the right side and the panel was in no way attached to the frame with any adhesive along that side. It was still secured fairly well from the physical fitment but it wasn't glued at all. This was a major problem and I thought my project was going off the rails.I removed the excess foam that had slid down the side of the panel with my hands (more on that later) to clear it off and give me a second chance. Next I went across the top horizontally with better results, similar to what happened along the bottom, but I still had not gotten the hang of using this foam. I went along the left side vertically and again had it sliding around and had to remove with my hands. I tried again and the foam sort of went into place and did what I wanted it to do but I still didn't understand why or what I had done differently to get the right seal and behavior of the foam.At this point, I decided to start sealing from the inside. But I knew I needed to move fast because I wanted to be able to sort of push the panel into place pushing it outward from inside the house to make for a better seal and fit. But I knew I wouldn't be able to do that if the foam had dried. However, my hands were now completely useless as they were covered with this stuff. After about a 5 minute diversion to the slop sink I had removed enough of the stuff to get my hands back to a functional state.I went to sealing the window from the inside and here is where I finally learned how to use this stuff correctly. I had a gap of about an 3/4" between the edge of the vent panel and the styrofoam backing. So naturally, when I started applying the foam sealer on the inside I was spraying the foam into that gap. And this provided an amazing realization.- Using this product properly: Apply minimal force on the trigger. You don't need to blast this stuff out at a high rate. Spray the foam into a gap (duh!) and the foam will expand to fill the gap (again duh!). As long as you are spraying it slowly into a gap it will expand to fill the area and create adhesion on all sides which will prevent it from being pulled down by gravity or just sort of glooping up on the surface. Just based on the description and purpose of this product and my intended goal with using it, I feel kind of dumb that I didn't do this right from the start.- The Process, continued: With this new understanding of how to apply this foam I completed the inside and went back outside. I carefully position the straw so as to make sure the foam would be quite literally injected into a gap. The foam expanded to fill the gap and didn't gloop up or slide downward. You can't just spray it on the surface...you have to stick the straw into the gap and inject foam into the gap.- Conclusion: End result was probably about as good as I possibly could have hoped for given my complete lack of experience with doing anything like this. I made a mess of my hands but after only about 5-10 mins of washing my hands with regular dish soap I had removed 75% of the adhesive from my hands. About a half day later 95% of is gone. So yes, be careful with handling it, and yes I should have worn gloves. But it's not THAT bad if you get it all over your hands. Your best bet with this stuff is going to be to press VERY lightly on the trigger when applying it. This will keep things neater and avoid the disasters I've seen in the customer images here.This product is great and I think completely lives up to what it says it does. There is a learning curve though but once you get the hang of it your result can be both functional and neat and tidy.