What is the function of gypsum-binder in dental investment?

The function of gypsum-binder in dental investment primarily revolves around providing strength and rigidity to the material when it has set. In the context of dental applications, the investment material must withstand the high temperatures and pressures associated with casting processes. Gypsum serves as a reliable binder, as it hardens to form a solid mass that can accurately hold the shape of the mold while ensuring that it can retain its structural integrity during the casting.

This strength is crucial for ensuring that the final castings made from materials like gold, silver, or other alloys maintain the precise details required for dental restorations. A well-formed investment with the appropriate strength and rigidity will lead to better outcomes in terms of the detailed reproduction of the dental structure. Other options relate to properties that are not the primary focus of gypsum-binder's role in investment material, which emphasizes the importance of strength and rigidity in the casting process.