Glass Bowls

Many people would like to be able to design beautiful art glass pieces but they are intimidated by the thought of cutting glass. With this project it is easy and fun to make these enchanting art glassware bowls using frit, pre-cut 8” circles and an earthenware slump mold. 

All of the glass materials used in this project are have been tested to have the same coefficient of expansion (COE), meaning that they will shrink and expand at the same rate. The COE of this glass is 96.

The first step of this project is the draw a pattern onto a 8” circle on white paper. You can use the pre-cut clear glass over the paper and trace around it to get an empty 8” circle to draw your pattern into. You can draw a very simple geometric pattern or a complicated scene.  Draw your pattern with pencil and then when you are sure of the pattern trace the pattern with a black pen.

Clean the pre-cut 8” circle of clear glass with soapy water or acetone. After drying the circle, place the circle of glass over your pattern template.  Using Elmer's glue in a slip trailer or directly from the bottle, trace the pattern onto the glass. Be careful not to squeeze too much glue and try to make your lines smooth and consistent. 

Sprinkle OG 002 Black Bird fine frit onto the plate and into the glue pattern. 

Allow the frit to rest on the plate for several minutes and then turn the glass circle on end over the paper with the pattern on it. The frit that is not on the pattern will spill off of the glass onto your paper.  You can rotate the glass to free any excess frit.  The frit on the paper should be free of contaminates and you should be able to pour it back into your frit container.  

(Note: Although it was not done on these samples, it is suggested that you make a black rim around the plate.  This will keep the FRIT from sliding off the plate when you move it to the kiln.  Or if you don't want a black border, you could use glue around the edge before applying your final colors.)

Allow the black frit pattern to dry. This can take several hours. You can hurry the process with a blow dryer. After the frit pattern is dry, select the colors that you want to fill the pattern in with.

For the funky checkered bowl pictured: the blue squares were filled with TG 003 Blue Bonnet medium grain frit and the green squares were filled with TG 006 Meadow medium grain frit.  Some of the blue spilled into the green areas and visa versa, but it did not harm the overall effect because the two colors used are fairly close in value.   

On the vine bowl pictured, 2 oz of TG 003 Blue Bonnet, 2 oz of TG 006 Meadow and 1 oz of TG 010 Sunflower were mixed together in a container and then spread evenly over circle and the vine pattern.  The transparent colors can be mixed over the opaque black used in the pattern with no effect to the black.

Apply glass separator to your shelf, or use kiln shelf paper if you have it.  (Glass separator is similar to kiln wash but a little finer.  Regular kiln wash can be used, but the back surface will be a little rougher.  When applying make sure the separator is smooth, or make a texture you wouldn't mind seeing on the back of the glass.)  Carefully place the decorated glass circle onto the 9” shelf. Some of the frit on the edge of the glass may fall off of the circle.  You will have to reapply frit to these areas. With a soft brush gently move any of the fallen frit off the shelves (catch it with your hands and remove it from the kiln).

Fire the circles at a rate of 600 degrees Fahrenheit per hour until the kiln gets to 1480 degrees Fahrenheit.  Allow the kiln to stay at 1480 degrees for 20 minutes. After the glass is fused at 1480 degrees, it is important to let the temperature drop to about 950 degrees and hold at that temperature about 1 hour. This is the “annealing” stage of the process. The temperature should gradually be dropped to room temperature after the annealing stage.  Some  glass kilns have these programs built in. 

After the kiln returns to room temperature remove the glass from the kiln shelf.  Wash the glass to remove the kiln paper.  According to the manufacturers written instructions, apply glass separator to the GM 04 - 8” round glass slump mold.  Heat the slump mold to 300 degrees to assure that the glass separator is dry.  Allow the molds to cool and place the fused glass circles directly on top of the slump molds and place the molds and the glass into the kiln.  Fire the kiln at a rate of 500 degrees per hour to 1220 degrees (notice that glass slumps at a much lower temperature then it fuses at). Soak the glass at 1220 degrees for 10 minutes. Allow the temperature to drop as quickly as possible to 950 degrees and hold it at 950 degrees for one hour. Then gradually drop the temperature to room temperature.  (It is important not to open the kiln below this 950 temperature until the kiln is cool.)  After the kiln is at room temperature, open the kiln to find the glass slumped beautifully into the 8” round glass slump mold.  Carefully invert the mold to de-mold the glass.  Wash and dry the glass to remove any glass separator from the glass and enjoy!

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