Questions about brazing fluxes

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I have two questions for the experienced guys:First question:  Have you ever noticed any practical difference between one general brazing flux (powdered) and another?  Here I'm asking about for use in brazing steel, or steel to brass, or for filling pits in bronze.Second question:  I bought some powdered flux the other day and asked the guy at our small-town industrial-supply shop if the flux could be used for propane brazing of aluminum (using aluminum brazing rod) - he just read the blurb on the jar and said 'works for ferrous and non-ferrous metals', so he figured it would work.  Is this the case?  Will this flux work?I ask about this because I saw a YouTube vid where a guy brazes an aluminum tube to a copper tube, using a propane torch, an aluminum brazing rod and some kind of (unexplained) white flux.  Process looked simple, but I don't have any idea what flux was being used.  And, unfortunately, I'm guessing that the guy advising me at my local industrial-supply shop is just a sales clerkThanks.
Reply:It has been quite a while since I have done any brazing. Based on a quickI reviewed AWS A 5.31 specification, I did not see a flux that would work on any combination of all ferrous and non-ferrous metals. That is not to say there isn't a proprietary flux that would not work. I saw listings for ferrous and a variety of non-ferrous such as copper and nickle along with their various alloys nor did I see a listing for an aluminum to copper. Soldering and brazing only differs by and arbitrary temperature. Soldering is less than than 450°C (842°F) and brazing is above that point. Ido not access to soldering fluxes. I suggest you check with the brazing flux manufacturer on line for a definitive answer.
Reply:i have been getting a nice joint on mild steel to mild steel  froma   flux called  brazo, which is boric acid/borax based.
Reply:Originally Posted by weldbeadi have been getting a nice joint on mild steel to mild steel  froma   flux called  brazo, which is boric acid/borax based.
Reply:Originally Posted by Joel_BCcould be used for propane brazing of aluminum (using aluminum brazing rod) - he just read the blurb on the jar and said 'works for ferrous and non-ferrous metals' . . .[I]I ask about this because I saw a YouTube vid where a guy brazes an aluminum tube to a copper tube, using a propane torch, an aluminum brazing rod and some kind of (unexplained) white flux.  Process looked simple, but I don't have any idea what flux was being used.
Reply:Originally Posted by rlitmanNope, won't work.  Flux needs to melt around the same temperature as the metal.The "super" aluminum brazing rods are mostly zinc based, so they melt before even aluminum, and the borax based flux won't be any good.  There are fluxes for aluminum, but it is generally awful, and the stuff can be pretty toxic (because it needs to be more reactive than even aluminum).
Reply:Hey guys,I use a brazing/sil-sol flux & an aluminum flux. Each are different. I use Lucas-Milhaupt Handy Flux exclusively, although have superb results with the aluminum flux from tinmantech. Here's the website & the information regarding applications.Dennyhttp://www.lucasmilhaupt.com/en-US/p...andyfluxes/13/Complete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:this product says it works on copper and aluminum----http://www.weldingtipsandtricks.com/uniweld-uni-4300.html
Reply:Originally Posted by yorkiepapHey guys,I use a brazing/sil-sol flux & an aluminum flux. Each are different. I use Lucas-Milhaupt Handy Flux exclusively, although have superb results with the aluminum flux from tinmantech. Here's the website & the information regarding applications.Dennyhttp://www.lucasmilhaupt.com/en-US/p...andyfluxes/13/
Reply:Originally Posted by boatbuoythis product says it works on copper and aluminum----http://www.weldingtipsandtricks.com/uniweld-uni-4300.html
Reply:Uniweld 4300 is a low temp soft solder.