investment
A refractory material used to create a mould for casting molten metal alloys in the lost-wax casting process for dental restorations.
Full Definition
In dental laboratory casting, investment refers to the plaster-like refractory powder mixed with liquid and used to surround a wax pattern to form a heat-resistant mould. When the mould is heated in a burnout furnace, the wax is eliminated, leaving a cavity into which molten metal is cast. Investment materials are classified as gypsum-bonded (for lower-fusing alloys) or phosphate-bonded (for high-fusing and base-metal alloys). Editors should note this is a specialised technical noun — not a financial term — in the dental laboratory context.
Usage
Usage note: Always disambiguate with 'casting investment' or 'refractory investment' on first reference in mixed-audience documents to prevent confusion with the financial sense of the word.
In Context
- "Phosphate-bonded investment was specified for the high-palladium alloy coping." — Metal casting work instructions
- "The investment was mixed under vacuum to eliminate air bubbles before the wax pattern was invested." — Lost-wax casting procedure document