Molding Quick Links

 

 

Mold Making

Making a mold from the sculpture is the next step in the mask making process. Our goal is to create a gypsum based negative mold of our sculpture. In doing so, we want the mold to be as accurate as possible. In addition, we want to make a mold that is good and strong, while not being too heavy and cumbersome.

We will look at the process of creating a two-piece waste mold. The term “waste mold” is used as the sculpture will be destroyed in the process, so it is important that the mold turns out or we’ll be left with no mold and no sculpture! No worries though, there is a process that mask makers have followed for decades which we will look at here. My steps follow the overall process very closely, and may differ from other mask maker’s processes slightly.

Supplies

The following list of supplies is what I currently use to create a mold. I prefer to have all my supplies laid out and ready to go within reach before I begin the process. Mold making is a messy process, so I don’t want to be digging through boxes, or have to look for anything once I begin. In addition, I do any mold making in my garage.

Ultra-Cal 30

The main ingredient to the process is Ultra-Cal 30, which is gypsum cement. Gypsum cement is denser and stronger overall than plaster. Because of this the mold will last longer and will lose detail slower over time, allowing us to get more casts from the mold compared to pottery plaster.

Ultra-Cal is sold in large 50lb. sacks. Because of the weight, you’re best to try and find a local supplier. I use Lance Gypsum in Chicago, but some large art supply houses or construction yards will carry the product.

I like to store my Ultra-Call in a large 50-gallon plastic waste can which keeps it good and dry.

Sifter

A sifter is needed to sift the Ultra-Cal into the water when mixing. I use a simple screen sifter.

 

 

 

 

 

 

Drill & Mixer

While this is not necessary, it definitely makes the job of mixing the Ultra-Cal and water a heck of a lot quicker and easier! The Mixer bit is a cheap purchase in any hardware store, and in my opinion, well worth it.

 

 

 

 

Burlap

Burlap is used to reinforce the mold and help cut down on the thickness of the mold walls. I buy my burlap in large rolls from the hardware or garden supply house. Although a 3’x3’ piece should provide plenty for one mold. I cut the burlap into several strips that vary from about 2-3” wide and about 6-12” long.

 

Clay & Cutter

Water-Based Clay is needed to build a dam wall around the sculpture. I like to keep my scrap clay from sculpting in a plastic bag for when it’s time to make a mold. 10-15lbs. should do depending on the size of the sculpture. A knife or wire cutter is needed to slice the clay into slabs.


Chip Brush & Airbrush

The chip brush is used to apply the mixed Ultra-Cal to the sculpture. Chip brushes are good and cheap, and be had at any hardware store. The Airbrush is great for blowing the Ultra-Cal into detail areas without actually touching the sculpture.

 

 

 

 

Petroleum Jelly & Mold Keys

Petroleum Jelly is needed to keep the two sides of the mold from sticking together. ABSOLUTELY necessary in the process!

Mold Keys are used to create a negative/ positive forms along the mold wall that help the finished mold sides lock together. I use keys from the Monster Makers, although they can be made from clay too. I have seen artists make wonderful keys by rolling clay balls and cutting them in half.

Pry Bars & Cleaning Brush

Pry Bars -are needed for separating the two mold sides once the Ultra-Cal has set up. Large flat headed screw drivers will work also.

Cleaning Brush - will help remove small bits of clay when cleaning the mold. I use my old tooth brushes for this.