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Read More Articles
The Future of Borosilicate 2010
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The future of Borosilicate
Degenerate Flame Off
Core Temperature
Competition & Success
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Universal Glass Concepts
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2008 Eugene Flame-Off


Core temperature, Universal Glass Concepts

Please read the Universal Glass Concepts article before reading this article. It is important to associate the colors and characteristics of the five stages of hot glass.

I would like for you to think of core temperature as a tool. Let me give you an example. If you heat a 12 mm rod to the gooey or liquid state and pull it immediately you will pull a long thin stringer. On the other hand if you heat a 12mm rod to a gooey liquid state then wait 3-10 seconds allowing the outside temperature to cool slightly the core temperature of the rod will provide enough heat so that you may stretch a thicker more controlled stringer. This will teach you to recognize the correct state of heat so that you get the results you are looking for with one pull.

Gathering glass is one of the most important concepts in glass artistry.
Maintaining desired thickness is crucial while manipulating hot glass for design purposes. This helps to maintain the continuity of the interior of hollow forms.

Most beginning glass artists have continuity issues because of two main reasons. First they don’t heat the core temperature of the entire piece to the gooey state before blowing. The problem is that the thinnest parts of the work are to hot while the thickest pieces aren't hot enough. When you begin to blow, the thinnest parts react quickest and become thinner; the thickest parts stay considerably hard and do not expand. The second common mistake the artist makes is heating the entire mass to the liquid state then blowing the piece too soon. Once the piece is liquid give it a few seconds to set up before you shaping it. This will also help keep scum or devitrification from forming on the surface of your work. Devitrification can form on the glass if the outside cools to quickly and the core of the work is still moving.

The key is to heat the piece to the liquid state then take it out of the flame allowing it to cool 3-5 seconds before you blow the shape you want, allowing the thinnest parts of the work to cool slightly so they don’t over expand. The goal is to utilize the core temperature of the thicker parts of the work to gather the mass without too much variation from thick to thin.

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