To get that shine off I soak my resin parts in Dettol! Yes thats right Dettol, i don't know what it has in it but cleans up resin and plastic release agents with a vengence without damaging or softening the parts. I soak them for about 30 - 45 mins then scrub with an old tooth brush. I then wash them in warm soapy water to get any left over Dettol and more importantly the smell, off the parts.
Give it a go!!
Cheers,
Jason.