Chemtools Liquid Fluxes
In metallurgy, a flux (derived from Latin fluxus meaning “flow”), is a chemical cleaning agent, flowing agent or purifying agent. Fluxes may have more than one function at a time. They are used in both extractive metallurgy and metal joining.
As cleaning agents, fluxes facilitate soldering, brazing, and welding by removing oxidation from the metals to be joined. Common fluxes are:ammonium chloride or rosin for soldering tin; hydrochloric acid and zinc chloride for soldering galvanized iron (and other zinc surfaces); andborax for brazing or braze-welding ferrous metals.
The terms resin flux and rosin flux are ambiguous and somewhat interchangeable, with different vendors using different assignments. Generally, fluxes are labeled as rosin if the vehicle they are based on is primarily natural rosin. Some manufactures reserve "rosin" designation for military fluxes based on rosin (R, RMA and RA compositions) and label others as "resin".
Rosin has good flux properties; it is a mixture of organic acids (resin acids, predominantly abietic acid, with pimaric acid, isopimaric acid, neoabietic acid, dihydroabietic acid, and dehydroabietic acid) which is a glassy solid, virtually nonreactive and noncorrosive at normal temperature but liquid, ionic and mildly reactive to metal oxides at molten state.