Woven glass..I would think that smooth on would be to "thick" to soak into it. If using fiberglass strips like UL or ULS bo-tuff then yes "smooth on" is the industry standard..I only build fiberglass backed bows and I use both ULS and UL. I do remember seeing someone on youtube using woven fiberglass as a bow backing on a board bow. I have only built 4 self bows and used deer rawhide as a backing over Mulberry or red oak myself, It was back in 1994 and we used titebond wood glue. I'm with Pat on not using glass on a self bow, The glass can over power the wood.. maybe linen or super thin raw hide would be better