ITEM NAME:50g Rosin Soldering Flux Paste Solder High Intensity Welding Grease LJ 50g Rosin Soldering Flux Paste Solder High Intensity Welding Grease LJ a.imagelink a:hover.imagelink {color:#60000;.Rosin flux is used to facilitate soldering. 1 x 50g Rosin Soldering Flux Paste. It also acts as a wetting agent, increasing the flow of solder and the efficiency of the soldering process. Net weight: 50g.