That's not gum on the surface, it's uncured resin!!! the resin with the wax in it does cure completely and sands very well without clogging the paper, but you do need to sand it before you recoat it if you let it completely cure. The resin I am using is unwaxed and I'm adding wax in styrene to the final lay-up to ensure all below it cures properly. So if I don't finish to top coat on the day I'm using V.E sure it will be a little tacky until I put a coat of resin with wax in it on top.
Gav > > > PE and VE resins exude a gum to the surface (surfaces?) when curing -
