I use Smooth-Cast 320 for my casting business.  It is 1:1 mixing so it's easy to use.  The main reason I picked this resin over another is that I can get it cheaply in bulk.  There are plenty of resins out there that are 1:1 that are good.  Typically if it's not 1:1 it's something special (like a clear resin or semi-rigid).  I usually go for 1:1 resins for general casting.

Try dusting your molds with talc (baby powder).  A light dusting of baby powder will give you a different texture than just the resin alone.  It also draws the resin into the details and helps get better casting.  After you put on your mold release (you are using mold release right?) and let it dry then give the molds a light dusting.  You can use a makeup brush and dab it in the talc and brush it over the mold.
You can try different materials to coat the mold with to get the texture you're looking for.  I've found that plaster will work but gave a heavier texture that wasn't particularly appealing to me.  You can also spray paint the molds and the resin should bond with it but I haven't tried that technique very much.

I hope it helps.

Itar

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