I stand in agreement with Dennisjay regarding the use of less expensive water
sealers. I've used the Thompson's Waterseal and the cheaper Ace Hardware
sealers that are listed for application on wood, cement, and other surfaces. The Sunbrella representatives suggest that the use of these sealers will decrease the lifespan of their product by embedding dirt particles that will abrade the fabric
. I still remain pleased with the less expensive brush on sealers and my Sunbrella continues to last well over ten years. My usual damage comes from chafe points that I try to avoid.
Thinwater's caution about the damage that these sealers can cause to the vinyl windows is important. I don't witness a runoff damage after the sealer drys, but any runs when brushing it on can permanently damage the clear windows and I'm very cautious with the edges.