Resin polishing?

I've been working on some cosplay fursuit things and ran into a bit of an issue. I used Alumilite High Strength-3 Mold Making Rubber (a silicone rubber located here) for the mold and cast with EasyCast resin.



My pieces turned sorta... matte/smudgy on the side that faced the mold.


This is the side that was exposed to open air--as you can see it's perfectly fine and shiny.

Here's the part that faces the mold that isn't shiny at all.

Is there any way to fix the already-cast piece so that it's shiny and the entire thing appears clear? Also are there any ways to prevent the same thing from happening again? (mold treatment of some sort?)

Thanks!