"I am not a plumber to trade but an electrical engineer. I do a fair bit of DIY plumbing for myself and others, I have also completed a large compressed air install using 15 and 22mm copper.
Anyway, I have used a full tub of this flux now, which for a DIY plumber is a lot of soldered joints! Used properly, this is a great product, helps the solder flow well but also cleans up the metal well without being too nasty. No problems with this product, do remember to wipe off any excess as it will go green overnight. Keep the lid on and tub sealed and this stuff will last for a good while. Good price and a very handy brush inside the cap.
Perfect for those who do few soldered joints and want a handy size tub.