High-quality paste flux has a working range of 1,100º1800º F, perfect for high-temperature silver solder applications. Specifically designed for use with Silvaloy 355 silver solder, Black Flux works particularly well on stainless steel and other refractory metals. Not for use on aluminum, magnesium, or Titanium. Paste formula is easy to apply exactly where you need it; cleans up with hot water. Mfg: Brownells SPECS: Meets Fed. Spec 0-F-499 Type B, AMS 3411, AWS FB3-C. ISO 9002 certified.