Monday, August 13, 2012

Introduction to Casting Part II

First as a 'public service announcement' the original post in this series was done in way back in February (LINKY) sorry I am getting part two up so late, but hey - there was like stuff going on and stuff! Here we have the assembled tools. You will need a container to mix your resin in, this container (red solo cup) must be DISPOSABLE as there will be hard resin left over from the casting in it. I have cut mine like you see in the picture because I can pour easily and maintain better control of the resin by pouring down that flap sticking up. The Popsicle stick is used to mix the two parts of the resin and in the cups you can see the clear and brown portions of the mix.

Here is what im using, you can pick it up easily enough at hobby stores, retails for 30 bucks - but with a certain 40% of coupon...

Anyway, I measure the brown and clear liquids so that I have slightly more clear that brown. The instructions say to use equal parts but I find you get a more rigid cast with a much more uniform color with slightly more clear than brown:

Pour the clear liquid into your mixing cup first, you will find that the clear is much more viscous than the brown and requires more time to get into your cup. Remember that once the two chemicals are mixed you have about 2 minutes of working time, so you want to move as quickly as possible once it all starts and you don't have time to be scraping the clear fluid out of the cup once you start:

Once your two reagents are mixed begin pouring, pour slowly so you don't trap allot of air bubbles down in your molds. Remember that the resin will expand slightly when it hardens so you need to fill your casts up to the edge of the mold, but not over - otherwise you will have some sanding to do so that its flat!

After you pour get out your trusty bubble remover, I use a paper clip with a bent end. I take this and run it along all the nooks and crannies of the molds and you will be surprised at how many air bubbles will come out. When you gain experience with your molds you will find that air bubbles will usually hang out in the same places and you will get batter at removing them quickly. I usually leave a bit of resin on the end of my bubble remover so it has a smoother surface u against the rubber mold. I seems to get the bubbles out better:

Once you get to this stage get anything out of the molds that you don't want stuck in there. The two reagents are reacting and will become hard resin in less than 45 seconds:

15 seconds later:

Once the white area moves across the entire mold I wait about 5 minutes before removing them from the mold. Every mold is different and you will slowly figure out how to best remove your casts from the molds without doing damage. Of these molds I push up the center back of the mold and the objective markers will come gently out. For other molds I pull up the corners, it just depends on the shape of your mold:

After each cast I check to make sure that there is not any portions of the rubber mold attached to the item I casted, if there is you will see errors in subsequent castings. Rubber molds are usually good for 20 - 100 castings depending on the quality of the rubber being used.

Here are some 'Wolf Banner Tokens' I casted up the other day, only took about 20 minutes to create the mold (then let cure for 24 hours) and cast all the tokens. Once you get a grasp of how it works you will find tons of uses and time saving things to do with casting. Like making scarab bases for instance...

Still Practicing_



  1. Thanks for the info. Speaking of scarabs. I plan to do exactly that sometime in the near future.

  2. I actually pour resin for a model train company and what we also do is use a little baby powder before porting the resin. I will clarify that it might only work or do anything substantial for our special resin, but try it out. If you do that make sure to use an excessive amount and then shake the excess off (generally back into the container you are. taking from. hope that helps some one

  3. I had been using Vaseline to make molds with (keep the rubber from sticking to the parts) but didn't consider baby powder as a mold release - thanks for the tip!