What are some of the preferred waterproofing products for the canvas cover? Last year I used some stuff that got added to water and applied with a sponge. I had it for my convertible car top. It worked pretty good for about a month, then I started getting water inside after a rain or two. A guy at the canvas repair shop was recommending some stuff in a spray bottle (can't remember the name of the product) but I was hesitant to buy it because it was around $35.00 which seemed a little steep at the time. I knew I already had the other stuff at home for my car and decided to try it out first. I need to do the canvas again so I thought this would be the place for good feedback.