So I picked up a gallon of canvak at cabelas because it was the only thing avaliable locally.($40) I applied it with a 3 inch roller and made sure it saturated the canvas. It took the whole gallon to do my popup which has a full and queen slide out so u can kind of picture how big it is. I applied it inside and out and thru the screen for the outside of the window covers. It does have a strong smell so I made sure it was a nice sunny 90 degree day to apply it and left it open all day long so it could dry. A week later when I opened the popup again, the smell was gone so I was glad of that. Yesturday I got to see how well it worked since it rained all day and all night and I'm quite pleased as it didn't leak at all, not even the seams which i never got around to putting seam sealer on. Just wanted to put that out there since their isn't a whole lot online about real world experience with canvak.