Mark Abildgaard
Kiln cast glass sculpture
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Process

(Please click pictures to see enlargements)








1. All of my sculptures are made of solid glass. In order to make a glass sculpture I begin by working in clay.



2. When I have the desired form and texture that I want I will make molds from the clay original with a high temperature plaster mixture.



3. After the plaster hardens I remove the clay from the molds. At this point the clay original has been destroyed so that if anything goes wrong with the mold I must start over.


4. Once the plaster molds dry I place them in an electric kiln and fill them with pieces of glass. This is when I can choose which colors of glass to use. I can control the coloring of the sculpture by placing different colored pieces of glass in different areas of the mold. Once the mold is  filled with glass I start a firing cycle that rises the temperature up slowly over several days.

5. When the temperature reaches the melting point of the glass, around 1500 F degrees, I will usually have to add more glass to the mold to keep it full.



6. Since all of the glass melting takes place inside a kiln this technique has become known as kiln casting rather than hot casting, where glass melted in a furnace is poured into molds.

    When the glass has completely melted and the molds are full I start a cooling or annealing cycle. Glass must be cooled slowly from its melting point down to room temperature or it will develop stress that can cause cracks. When the kiln has completely cooled down, usually after one week, I can take the molds out and break them apart to remove the solid castings. If anything goes wrong with the castings at this point I will have to start over with working in clay as the molds are destroyed while removing the glass. I may make a series of sculptures that are similar but no two pieces are ever exactly the same. Each sculpture I make is a true original. I have to finish the castings after I remove the plaster molds. I use a diamond saw, belt sander and sandblaster to smooth rough edges and fit separate pieces together. The surfaces of the sculptures are the result of the texture that was in the plaster mold. Since most of my sculptures are made of more than one piece I use Hxtal, a special epoxy glue which is made for glass to bond the pieces together. This epoxy bond is stronger than the glass itself and will not deteriorate in ultra violet light.
    
     My glass sculptures are sensitive to light. I prefer to view my sculpture in a natural light source that will change during the course of a day. In viewing a sculpture over an extended period of time you will see how your perception of the piece changes with the light. Because of the thickness of the glass I do not recommend placing my sculptures outdoors. Wide temperature swings can cause the glass to crack. Placing sculptures indoors near a window is fine. I would avoid placing a glass sculpture close to a fireplace or heating vent in order to avoid temperature shock.