How to make the best liquid solder flux cheap, fast and easy.
To the left is a video showing the process of making your own flux.
This flux is extremely nice to use. It does not even require you to thoroughly clean the surface of the metal.
Coat your PCB or other boards with it and let them dry. No need to use any other flux thereafter.
Add some isopropyl or denatured alcohol to a small jar or plastic medicine bottle.
Add some chips of Kalifonia resin flux. It is cheap! And great even in the solid form. Get it on eBay.
The resin will dissolve overnight. The liquid will change to the golden resin color.
Add more chips, a bit at a time, until they do not dissolve. At that point you have a saturated solution and powerful flux.