Glass Kiln Casting

Casting glass in a kiln is a very different process than that used in glass-blowing or slumping. It is much more time consuming and process oriented, and in fact it has more in common with bronze casting.

I create the original sculpture in plastelina and then use silicone to make a flexible mold. Once dried and cleaned, I’ll pour wax into the silicone to create a hollow copy of the original sculpture. I clean the wax copy and possibly rework it, and paint on 8 to 10 layers of something called “mold mix 6” to create a heat resistant shell mold. Then I take a blow torch to it to melt out the wax and to harden and cure the mold. I wrap the heat resistant shell tightly in fibre blanket and wire for extra support and then fill it with chunks of glass, trying to strategically place the colours where I want them to be in the finished work. The work is placed in the kiln and is fired slowly for 3 to 7 days depending on the size of the work. This is the half-way point. Once the work comes out of the kiln (if the melt was successful!) the cleanup process includes glass saws, wire brushes, sanders, sandblasters, polishing and a lot of elbow grease.

Each finished piece of kiln cast glass, from the smallest to the largest has gone through this weeks long process. I hope this explanation of the steps involved, will help you enjoy the unique and beautiful qualities of kiln cast glass all the more.

Connie Geerts


3 stages of the process


Finished Sculpture