Scotch Guard is a well-known and very trusted brand when it comes to protecting fabric. They make a fabric sealer that maybe applicable for the southwest and other areas that don’t see a lot of cold weather or snow.
For most people though, the best Scotch Guard product would be their outdoor sealer. This is designed for all weather use. This makes our list because Scotch Guard is a great brand, and we like so many of their other products.
The big drawback with ranking it higher is that a single can will cover about 20 square feet of heavy fabric. It is an amazing product for covering light vinyl for tents or other items. For these products, a single can will product 60 square feet of fabric.
For the heavier fabric that will used in a gazebo or pergola cover, it simply soaks into the fabric requiring more solution. An 8′ x 10′ gazebo would require 4 cans of the Scotch Guard sealant whereas the same gazebo could be covered with a single bottle of the star Brite listed above.