Mar
6
2019
Laura Thompson
My husband Michael and I have been working together for 9 years designing and creating our kiln formed glass objects of art. I have a fine art background and worked in 2-D for the majority of my adult life. I became hooked with glass when I learned how to make glass beads. Michael used to build custom homes, and though he does not have the art background that I do, he is creative in his own right. I took some glass workshops and read a lot of books about kiln work, and transferred my knowledge to Michael. While Michael does all of the major glass cutting, we both design every one of our pieces. We are constantly experimenting with different ideas and trying different techniques and in doing so, we are constantly learning about the process.
Our studio consumes the entire basement of our home located outside Chicago, Illinois. We have four kilns; a 14″ x 17″ unit which I use for testing and annealing marbles and beads; a 48″ x 30″ x 20″ unit (our first kiln which Michael built); a 30″ x 60″ x 12″ unit and a 44″ x 60″ x12″ unit. We have a large belt sander and a 20″ lapidary machine (Michael built this as well) that are used to grind the edges of the glass as we are building a design, or to finish the edges of some of our pieces.
The majority of our work requires 2 or more kiln firings. Depending on the design and complexity of the piece, some may require up to 4 firings before they are finished. Using sheet glass that is made specifically for kiln work, we hand cut the glass according to our original designs. We grind the edges so that the pieces fit together without any gaps. All of our work is at least 2 layers of glass, with the colored layer on the bottom and a layer of clear on top. Some of our work has surface decoration consisting of diachronic and opaque glasses, which are arranged on top of the clear layer. Our vessels are 4 to 8 layers of glass, depending on how tall we wish to make the finished piece.
Each individual piece of glass that makes up each entire composition must be cleaned thoroughly and then reassembled in the kiln on either a ceramic or fiberboard shelf, with a sheet of fiber paper between the glass or the shelf. The kiln is fired to 1480 degrees F., at which point all the pieces and layers of glass melt or fuse together to form a solid. The glass must be heated slowly to avoid causing thermal shock and to squeeze out any major pockets of air that are trapped in between the layers; firing to full-fuse for a 2-layer design takes approximately 4.5 hours. We allow the kiln to sit at 1480 F. for 30 minutes to ensure the edges have sealed and are nicely rounded, and the surface is uniform. When we have visually determined that the pieces are done, we open the kiln and rapidly drop the temperature inside to flash cool the glass. We then close the kiln and begin the annealing (cooling) process.
Annealing involves equalizing the temperature of the mass of glass and the temperature of the kiln shelf, so that any stress in the glass due to uneven heating, manipulation or slumping is relieved. To do this, we must soak the glass at 960 F. for a specific period of time (depending on the size and thickness of the work.) The temperature is gradually lowered from 960 F to 815 F, and then from 815 F to 725F. The range between 960 and 725 F. is where permanent stress can develop. When the kiln reaches 725 F. it is turned off and allowed to cool to room temperature. Our firing schedules for a 2-layer design, whether for fusing or slumping, are roughly 22 hours.
To shape our pieces, we set our fused blank back into the kiln on top of either a ceramic fiber or stainless steel form. This time the kiln is fired even slower still to a temperature of 1250 F., at which point the glass becomes soft enough to bend or sag over or through the form. Our ribbon wall hangings and sculptures are slumped over 4″ and 2″ diameter stainless steel pipes. In the case of our vessels, the glass drops through a hole in the center of a fiber shelf. The height or depth of our vessels is determined by the length of time we allow it to sit at the slumping temperature. We do not press the glass into a mold – gravity and the temperature inside the kiln do the work for us. And once again, all pieces must go through the long annealing process to avoid any permanent stress.