The term warm glass refers to fusing and other glass processes which take place at between 1100 – 1700 Fahrenheit. It is merely warm when you compare it to the glass blowing process which often exceeds 2000 Fahrenheit.
Glass fusing is the process of using a kiln to join together pieces of glass. If you apply heat to glass, it will soften. If you continue to apply heat, the glass will become more fluid and flow together.
Slumping is shaping glass using the heat of a kiln. Sometime a mold is used to take on a certain shape. Other kinds of techniques are combing, which involves using a tool to distort the shape while it is hot, and fire polishing, which uses a kiln to heat the glass just enough to make it shiny and smooth.
When the right kind of glass is heated and cooled properly, the resulting fused glass piece will be solid.