In my opinion, if you use the resin spray carefully, then yes, you can get a nice glossy surface as if the resin had cured in a shiny surface silicone mold. You can see what I’m talking about in this video: https://www.youtube.com/watch?v=ITsGX4PcPrE&t=5s
Thanks. I’m a first timer. My mold wasn’t real good. I sanded casting well and used resin as a coating. Came out clearer but it needs sanding again as it’s not smooth. Worried that sanding will dull finish again. If so prefer to use a spray and unfortunately its for Xmas so can’t order yours. Hoping polyurathene will work.