Solder flux is used to clean and prepare surfaces for soldering and to control oxidation. It removes impurities that inhibit adhesion during soldering. Flux can be made from a wide variety of components, with rosin the most common. Flux can be dispensed from a pen or spatula, spread directly on surfaces or incorporated directly into solder. Standard rosin flux leaves behind residue that is corrosive to circuits over time. Flux removers made from trichloroethylene are used to clean this residue away.