Review on SRA Rosin Paste Flux 135: Unbeatable Flux for Optimal Soldering Performance by Tim Bunker

10/16/21 Update: You can gel this with some isopropyl alcohol 91% or higher. I did not do it scientifically, but poured a small amount of alcohol into a small glass jar with a spoonful of paste. Then I boiled the container twice until the solder was liquid. Stir with a toothpick (or whatever you have) and let cool. On cooling it turned into a gel. Then simply place it in the container of your choice. I use syringes to apply it to small SMD components. I always thought that since the solder comes with a rosin core, no flux is needed. While this material isn't technically widely used in the field you'll be working in, it makes the job much faster. The solder joints accepted the solder quickly and desoldering was much faster. At first glance, the paste may seem tough. I just poked it with a toothpick and it spread easily where I needed it. Just use isopropyl alcohol to wipe it off the boards when you're done.