Aerospace Material Specification 3411 is a silver-brazing flux in a paste form.

This black flux meets Federal Spec O-F-499 and AWS FB-3C.

AMS 3411 is engineered for use in high temperatures may be used with silver or other brazing alloys up to 1800℉ for extended or uneven heating; specification is also well performing in low temperatures. Ideal for welding stainless steel or wherever higher temperatures or extended heat duration. Not recommended for use with alumminum, magnesium, or titanium.