What is kilnforming?
Kilnforming is the process of shaping glass in a kiln with heat and gravity. There are many methods and techniques that are related to kilnforming, including glass fusing, glass slumping, kilncasting and printmaking.
There is a type of glass called "kiln-glass" that's specifically manufactured for use in a kiln. One of the properties of this glass is "compatibility", which allows it to be fused to another disparate piece of glass in a kiln.
When glass is heated in kiln, it becomes soft and the consistency becomes sticky and almost honey-like. As the temperature continues to increase, the glass becomes more liquid. Gravity takes hold of the molten glass, the molten glass fills the space in which it's contained, and fuses with any other pieces of compatible glass.
When the temperature inside the kiln is returned to room temperature (after an appropriate anneal soak phase), the glass will resume its crystalline structure in the shape it assumed at process temperature.
Video lesson: What is kiln-glass?
Video lesson: Firing: Basic Principles
Video lesson: Firing: Basic Applications
Video lesson: Slumping Basics
Video lesson: Harnessing Flow in Kiln-Glass
Video lesson: Why did it break?
TechNotes 4: Heat and Glass
History: The Bullseye Story