I took up repairing electronics stuff about 2 years ago when the circuit board on my GMC Sierra stopped working. Saw that they had a great many such problems with solder joints failing on that particular circuit board, and decided to buy the right equipment and learn to do it myself with the help of some Youtube videos. The first major thing I learned was the importance of a good rosin solder flux for PCB board repair. It makes the solder flow and bond to the components, and not go where the solder mask is on the board. Almost seems like magic the first time you see it. Anyway, the stuff I have been using works great, but it has 1 method of application. A little squeeze bottle that uses a fine needle to place the rosin on the printed circuit boards. The resin (or rosin), whichever spelling you like, is a thin liquid in that bottle, so it will flow like water through the tiny application needle. It can be a little messy and it tends to burn off the hot soldering tip fairly quickly. The Rosin in this review, is a solid at room temperature, and comes in a nice screw top tin. To use it, you dab the hot soldering iron tip into the rosin, then proceed to solder normally (with the fine soldering wire). Just another way to achieve the same goal. It is good to have different ways to do it, because for some situations, one of the 2 methods will make the job easier and better. This product is a very good way to use the second method. The flux follows your soldering iron tip to the work, and does not tend to drip all over the place and make a mess. If you are going to solder much at all, highly recommend this flux. There are also plenty of Youtube videos that show how to use various types of flux. Cheers!

I use it to bring life back into dried solder paste. Stir in and the paste is like new. Officially, you can't do that for mil-spec production.