After our polyester resin work on the Water project, we embarked on a much more complicated mission. We needed to make over one hundred lightweight scales from a handful of patterns.

So we began with clay. SULFUR-FREE clay, this was incredibly important as we were going to used silicon molds and ANY sulfur will inhibit cure. We finally used Chavant Clayette Medium, a nice easy to work with sulfur free clay. Using this clay we sculpted the scale patterns.

Now to prepare to mold. First we had to seal the clay patterns with Acrylic Spay. NOT lacquer. Not anything else, but acrylic. This is a mistake I made and lead to curing problems. Acrylic spray can be found online or in your local craft store.

Next we need a molding box. I mounted the clay pattern on a piece of foam core using hot glue, and traced an outline ½” to 1” from the edge of the clay. I then built up foam core walls on these lines and secured them all with hot glue. I then sealed anywhere that looked like there were cracks with hot glue. Lastly a fine spray of acrylic was applied.

Now for the fun part- the silicon. I used Smooth On Mold Star 15 Slow. This is an easy to use silicon with a durable hardness that still captures tons of detail. Best part is it mixes at a 1:1 weight or volume ratio. I had already measured the volume of the box with rice, so I just divided the total volume in half and poured equal volumes of part A and part B and mixed. I SPRAYED THE PIECE AND BOX WITH A UNIVERSAL MOLD RELEASE. Then a poured the silicon.

This silicon had a 4 hour cure time. So in 4+ hours it was time to demold. I deconstructed the box and pulled out the clay. The mold sometimes was a little dirty so alcohol and q-tips cleaned it up. In hard to reach areas I just waited to cast the first piece and this cast would pull all the residual clay from the mold.

Now for the casting. We had chosen Smooth On EpoxyCast 690 as our casting medium. We had used polyester resin in the past, but decided to switch to a clear casting epoxy because it cures better in custom molds.

We needed these casts to be light, since they were to be hung on garments, so we mixed Glass Air Balloons to lighten the medium. We added these in a 1:1 ratio by volume.

Color became and problem with the milky Air Balloons, so we settled with pigments and luster pigments.

So the process became as this, mix the epoxy in a 100:30 ratio by weight. Double the volume by adding equal parts of Air Balloons. Add pigment as desired. SPRAY MOLD WITH MOLD RELEASE (Not necessary but will extend the life of the mold). And pour.

One hint, keeping careful notes of mold volume and pigment ratios help reduce waste and keep pieces uniform.

EpoxyACast 690 had a 24 cure time, so 24 hours later we remove out brand new, light weight cast.