Soldering irons with flux (rosin) included

Flux (rosin)

— the general purpose of all fluxes is to improve the efficiency of solder "setting" when soldering. Such compositions perform several functions at once: they remove oxides and slags from the surface of the parts to be joined, prevent the formation of new oxidations, promote the spreading of liquid solder and more dense wetting of parts with it.

As for rosin, this is one of the most famous and common fluxes used in hand soldering. Rosin is extracted from the resin of coniferous trees, it is quite simple to obtain, and also safe to use. This type of flux can be used in both solid and liquid form. Molten rosin removes oxide films well on the surface of most metals, but it is poorly suited for heavily contaminated surfaces.