My first time casting parts with the Hirst Arts castlemolds. I used plaster from a craft chain store. I wanted to try the cheap stuff first and see how the molds work. I wanted to have some experience with the process before ordering special casting material (like dental stone or the merlin’s magic stone.)
I followed the process as described on Hirst’s web page. I would have liked to see a mixture formula (e.g. 1 cup of water for 3 cups of powder) but after doing a few castings I realized that there is a good reason for mixing the material by eye.
Thicker plaster mixes make denser blocks but are more prone to bubbles. Lighter mixes are less prone to bubbles in the mold but make a weaker block.
