For Nave's Kilik costume, I learned a few things about resin casting.
Amethyst Angel's Casting Guide is a really great run down of what materials she used and the advantages/disadvantages of each. The ladies of HCC have also compiled this list of tutorials and, more specifically, a guide on casting with polyester resin.
I used polyurethane resin and silicon mold making compound from Micro-mark's casting starter kit. It's a great deal, and it really does have everything that you need to make a few molds. To finish the molds though, I ended up using about two and a half bottles of each compound. Yeesh.
Also, to preface: I'm a chemist. I'm used to handling dangerous chemicals at work. While resin casting is actually fairly simple, pleeeeease wear gloves of some sort.
- The initial sculpt is the most important part, and silicon takes the texture of whatever you pour it on. After I got everything done, I realized that I really should have taken extra time to smooth things out and get rid of the finger prints. Woops.
- Display size foam core boards and hot glue = awesome for making the mold boxes if you don't have access to oil based clay. They can be re-usable to an extent if you make smaller molds in the future and you're careful about tearing the mold box apart.
- If you have multiple casts, give yourself more than two days to do it ._. I rushed the last ring and it was a bit squishy in comparison to the rest and took longer to set because I wasn't careful about the measurements.
- Red Solo cups and plastic utensils? AWESOME FOR MIXING EVERYTHING.
- Careful about the undercuts on your sculpt... The phoenix heads for the knee guards had a pretty deep undercut and it was a rather large pain in the rear to pull the sculpt and the casts from the mold. Trust me, it wasn't fun.
- Do everything in stages rather than seeing one thing through all of the way (i.e. finish all of the sculpts, make all of the mold boxes, do all of the pours). I generally do my work that way anyways, but if you prepare all of the molds for the pour all at once and you accidentally mix too much molding compound for one of the molds, you can pour it into another one without any worries because...
- Silicon sticks to itself very well. I cut up my first ring mold and shoved it into the phoenix mold to bolster the amount of molding compound I had left. I will most likely be destroying these molds if I have to do a large cast in the future.