In addition to 3D printing molds directly I have also been working on more “traditional” forms of mold making taking 3D printed positives and creating plaster and silicone molds from them. While the plaster molds are much cheaper than silicone it’s much more difficult to separate rigid plastic parts from rigid plaster molds. Silicone does a much better job of separating easily and efficiently.
First coat of silicone captures the detail of the form
Working from the “Barbe House” terracotta I printed a positive / negative form. I placed the 3D printed form on a bed of clay embedding at the parting line and poured silicone onto it to a depth of about an inch all the way around. In order to save money on silicone I leveled the back of the mold with plaster. Once this set up i flipped the mold and peeled back the clay being careful not to dislodge the 3D printed positive.
Two part silicone mold of “Barbe House” terracotta by Louis H. Sullivan
Silicone is pretty cool in that it will not really stick to anything apart from itself. Therefore it is super important before pouring the second side in silicone to make sure there’s good coating of mold release on top of the first side. Otherwise the two halves of the silicone mold will stick to each other and it’s game over. Once the second half was an inch or so of silicone thick all the way around, and cured, I filled in the back once more with plaster.
3D Printed “Barbe House” positive and Wax cast “copy”
For the casting i chose to use foundry wax. Apart from a tiny wee hole at the very tip of the form it came out perfectly.I’m hoping that using rotocasting might make for a more even cast. I want to try pouring it with Aqua Resin and some different colored waxes too. Also i’m excited to cast the wax forms in aluminum and bronze soon.
