A new box of wax paper with 75 square feet is almost enough, had to run to the store for a second box. I left the wax paper in place until the following evening (30ish hours after final coat) when I removed it, the gelcoat was mostly cured. It was difficult to apply smoothly, some areas had wrinkles, if there was air in the wrinkle it was still tacky. The sides were still kind of wet (sticks to your finger when you touch it, as opposed to a clean finger tacky feel with the first two coats). I pulled off the wax paper, mostly it removed nicely. In the places where the gelcoat was still wet it was messy. I used the same wax paper just turned it over and reapplied to the areas that were not completely cured. Another 24 hours later the gelcoat had completely set. But is is not smooth. I had anticipated some sanding because I used a brush, but this is far from just some brush marks. Applying the wax paper to such a larger area (with a liberal application of profanity) resulted in a very uneven final surface. here