A flux that is brought to the oxyfuel gas torch by passing acetylene through a liquid flux held in a dispenser. The dispenser is connected in the acetylene line between the regulator and the torch so that all of the acetylene passes through it. The flux in a vapor form is picked up by the acetylene and carried through the hose and torch to the point of welding. Vapor flux provides automatic fluxing and accurately regulates the amount of flux used; it permits continuous welding without stopping to reflux the rod.