It is always difficult to diagnose brazing problems from just a picture alone. Although in your case one can see you used the wrong flux. Even though it can be obvious the joint got too hot, more information is needed to know how it got hot, like was the flame too close? or were you too slow flicking the flame away? There are all kinds of possibilities. It really takes observation to figure out what is going wrong. I'm positive your tip is way too big for a beginner. A bigger the tip requires faster reactions. Most people starting need extra time to interpret the heat indicators and then think of how to move in response. Use a tip below .040" in diameter.


Your goal is to control the brass puddle by keeping it in between the liquid and solid state. Primarily you do this with a flicking motion (like unterhausen said) so just as the puddle takes the desired shape the flame is flicked off and then applied again as more brass is added. Like an on off switch.


Most welding stores sell brass granular flux in a yellow pint sized can. Or as least they used to. It is designed so that the rod can be heated up and then dunked into the can so some flux will stick to the end of the rod. Some can be taken out and smashed up a bit and made into a paste by adding water. This brass flux is nowhere near as good as Gasflux type B or the stuff from Cycle Design. Get the right brass too. Its like wanting to learn to cross country ski with down hill skis. It doesn't work and one doesn't learn using the wrong tools.