12.9.2.1 Filler material proper formulation is essential for furnace brazing applications, especially in vacuum furnace brazing, where sometimes a partial pressure is required to prevent vaporization of the filler metal resulting bad brazements. Specific alloy formulations shall be designated on the Brooks Automation drawings.12.9.2.2 Filler metals are available in several configurations designed to accommodate various brazing environments, with the most popular (in furnace brazing) being the "pre-form" type.12.9.2.3 Pre-forms, used commonly in high-volume production brazing, are filler metals that have been stamped or shaped into washers, rings, shims, formed strips, or wire to fit over the joint being brazed as well as ribbons and sheet (foil) (see Figure 12-27).