Cowboy, I used some exterior poly (don't remember the brand) on a very simple yard sign around 2001. Purchased from a local lumber yard. It lasted less than 6 months. It was exposed to the Wyoming sun and wind during the spring and summer months. Best clear that I ever used for outdoors was permalac sold by Sculptneuvu. It lasted over a year in the Southeast TX sun and rain. Never tried the sikkens but know that Joe Crumley speaks well of it as do a few others on here. Just beware of the exterior polys.