Cutting Ultracal 30 with a bandsaw

I recently sculpted a closed greave to use in a Dr. Doom set of armor.

Here is the rough stages as again I forgot to document the finished pieces. I started with a piece of PVC cut to the length of my shin and then built up clay on top of it to the desired shape. I then added a shape shown in artwork with Doom's legs showing.

This addition created undercuts in the ultracal mold that I was originally unaware of. This created a problem because if I poured ultracal in to make a positive it would definitely lock the mold. After searching the web for several days I found nothing regarding cutting it in to two halves for ease of release. I decided to try it on the bandsaw figuring the worst that would happen when I cut the ultracal mold it would gum up the blade or dull it completely. Surprisingly it did neither. The bandsaw cut through both molds at an even speed with no damage to mold or blade. 

I made slight turns with the piece to make sure the mold fit back together precisely but the process worked well.

So last night I poured the casts. Always remember to coat your molds with some form of release agent. I nearly forgot last night until the last second to coat the inside of these molds or I would have ended up with bricks.

Here are the casts fresh out of the molds after some delicate coaxing.  They will look great once they have been sanded a bit. I should get some good vacuum formed pulls from these pieces. The most important thing to remember if you are working with plaster molds and making plaster casts is to insure there are no undercuts. That will guarantee you will have to destroy your mold to get the piece out if any undercuts are present. I primarily work with the Ultra-Cal 30 for molds as it is readily available from ceramic supply stores and very inexpensive compared to silicone and urethane molding materials and the molds will last forever. That being said I will be making some molds down the road using these more expensive materials as the pieces I want to cast will be more complex but for basic shapes like I am doing now the Ultra-Cal works well for it.

Next up is to build some MDF risers as its always good to have your pieces up a bit when vacuum forming to insure you have good pulls and access to cut off.