What is investment?
Investment is a mixture of materials used to make a mold. In general, investment mixes for kilncasting glass are composed of three basic ingredients: a binder, a refractory, and modifiers.
Some artists use readymade investment mixes like Bullseye Investment, which is plaster-silica based.
To learn about creating your own investment recipes, see TipSheet 8: Basic Lost Wax Kilncasting.