One thing to watch for is the numpty in the store (or the one in charge of the webshop) trying to pass of ally brazing flux as welding flux. The 'speshial' ed case behind the weldability site doesn't help matters...
it used to be 'aluminium #36' for brazing and 'aluminium flux' for welding. Depending which bit of the SIF/weldability site you look at aluminium #36 either still exists or it has been replaced with aluminium #16 *. Aluminium welding flux is described as brazing and low temp welding once you click through. It never used to be, hopefully/probably it's a mistake on their site
* This makes more sense when you consider that SIF call 4047 wire 'aluminium #16' and they used to have a wire called #36 which was basically the same thing. 4047 can be used for both welding and brazing as it melts at around 80C less than pure aluminium