Thursday, November 10, 2011

Resin Casting Tutorial

Now that a mold is finished we need to pour some resin.

Lets make these.

Smooth-Cast 305
Once again this product is mixed at a 1:1 ratio by volume and has little or no odor.

It has a 7 minute pot life and a 30 minute demold time.

I recommend getting some squeeze bottles like restaurants use for condiments to make it easier to pour.

I use Alumilite's Black dye to get a gray resin.  305 is usually bright white.  A few drops in the A side jug and shake till blended. Go slow with this and test until you get a shade you are happy with.

Tools and work area
I use a marble cutting board for any of my messy work.  Hot metal, super glue and resins scrape right off with the razor scraper.

  • Syringe for injecting resin into the mold, or pulling resin through a vent gate.
  • Graduated mixing cups, labeled in CC
  • Mixing Stix
  • Rubber bands to keep molds together
  • Clamp(s) for molds
  • Hard board or plastic card used when clamping the molds.

Clamped Molds
Using a hardboard or thicker plastic card line up the halves and hold them together.  Use rubber bands or clamps.  You have to figure out the right amount of pressure for your mold. Too little and the resin will seep out of the bottom, too much and you will warp and deform the cast.

Mixing and pouring tips

  • Shake both sides of the product to ensure they are fully mixed, especially is you are using a resin dye.
  • Stir the A&B sides well, make sure it is completely mixed.
  • With this mold I was able to pour directly into the main gate, I used the syringe slowly pull resin & air pockets up through the vent channel.
  • Rotate and shake the mold to help free any trapped air pockets.
  • Wear gloves you don't want mixed resin on your hands.

First Cast from these molds
On this pull (that's what a casting is called) you can see the middle claw did not form because there was a small amount of silicon that needed to be removed from the vent.  A few small air bubbles but over all a very nice first pull, means this should be a very good mold.

On this pull we see a few air bubbles and the toe had a trapped air bubble.  Still better than most packaged and sold Finecast.  The toe bubble was solved in future pulls by rotating the mold while the resin was liquid, to allow the air to escape.

The vents on this mold did work right the first time.

With a little work these legs will be usable, a small amount of green stuff and less time than I have spent on most ForgeWorld I have gets a very good set of bug legs.


  1. Awesome work. You are getting a few small surface bubbles, one trick you will want to try is dusting the mold with baby powder then shake off any excess so only a very light dusting is left. This will pull all your resin against the modl and get rid of any micro bubbles.

  2. Nice demonstration, thanks for the tutorial!


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