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About Warm Glass

9 1/2" fused glass plate using iridized glass. A pattern bar of red and white accents is incorporated in the center.
Iridized Black Plate

A Multi-Step Process

Warm glass is about the reaction of fusible art glass as it is heated to kiln-forming temperatures of up to 1500⁰(F). While that reaction is generally predictable, the varying properties of the specific glass and the exact firing conditions make each firing unique. This 9 ½” square plate is made from more than 40 pieces of 4 different kinds of glass. The finished piece is the result of 4 separate firings taking over 50 hours of firing time. It one of my favorite works. I was almost sad when it sold.

Step 1 - Starting with a Pattern Bar

The organic design of color in the center of the plate is created from a pattern bar. The bar itself is approximately 30 strips of glass in three colors (black, white, and red) that are fused together to form a 2” x 6” x 1” glass brick. Firing time for this step is 16 hours due to the thickness of the glass.

It is the profile of the bar that is of interest, so the bar is cut into 10mm slices using a diamond bladed tile saw. Once the design layout of the slices is determined, a glass grinder is used to square and smooth the edges of each slice so they fit together nicely in the center of the plate. Finally, a wet belt sander is used to smooth the surfaces of each slice. All of this work is referred to as cold working. The images on the left show the setup of multiple strips of glass that will form the pattern bar. Notice that the black and white strips have are already fused together from a previous project. On the right are images of the slices cut from the bar and how they will be arranged to the plate.

Steps for making and using a pattern bar
Pattern Bar in Progress

Making the Base Plate

The second firing creates the “blank” or base plate. To complete the plate, three layers of glass (clear, black, red) are wrapped around the organic black/red/white color design. Firing time is 14.5 hours. The image blow shows the sequential steps to create the blank. It is three layers of glass; iridized clear, black and red. Each layer is four piece of glass to encase the pattern bar design. Note that the base plate is fired top side down to ensure the multiple pieces fuse together.

Sequential steps to assemble the base plate
Building the Base Plate

Fire Polish

The base plate was fired with the top (clear) side down leaving it with a flat, textured surface. Additional cold working is done to smooth and round the edges of the plate. Then it is fired again top-side up to “fire polish" it, giving it a smooth glossy finish. Firing time is 11.5 hours.

Forming the Plate

The fourth and final firing is to shape the plate by slumping it into a prepared bisque mold. As the glass becomes molten, gravity pulls it down to conform to the shape of the mold. Firing time is 11 hours.

The Final Product!

At long last, the reward. Opening the kiln for the final time reveals the culmination of days of work. Is it worth it? Ultimately, I suppose a customer buying it answers that question. For me however, if I never sold it I would still make it.

Images of the finished product
Finished Product

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