Phosphor Copper, one of the earliest known metallic fluxes used with copper based alloys is produced by H. Kramer & Co. It is primarily a deoxidizer or reducing agent, but also a hardener, adding phosphorus in the production of phosphorus containing alloys. It is available in shot form or as a 12 inch diameter semi circular waffle weighing approximately 12 pounds, packaged in drums. Since the alloy is very brittle, the waffle is easily broken into small pieces. The shot is also offered as PHOS PAK, in precision measured 1, 2, 3, 4 or 5 ounce packages.
While Phosphor Copper is primarily known as a deoxidizer, its ability to reduce surface tension dramatically improves fluidity, reducing pouring temperatures.
As a deoxidizer for red brasses, semi red brasses and tin bronzes, Phosphor Copper is typically added to the melt in a ratio of one to four ounces per 100 pounds, depending on such factors as furnace type and alloy chemistry.
When using a stationary furnace, the crucible should be removed and skimmed. Phosphor Copper is then introduced to the top of the melt, immediately plunged with a skimmer and thoroughly mixed.
In a tilting furnace, Phosphor Copper may be added into the stream after the ladle has been partially filled to facilitate mixing.