Doug Fattic 

Yes, Gasflux makes both a powder Type B and also a powder type G that I like using for silver on stainless steel because it has a bit higher temperature range. I put the powder type B in one of those old powder flux cans that the LWS store used to sell. Just like John, I heat up the end of the rod and put it in the can so flux will stick to the end and then I can apply it to where a bit more is needed while the joint is hot. The can had a little hole in the lid that the short used ends of the brass rod could rest waiting to be used. I don't think those cans are available in more but my rusty one from the 70's still works.

Gasflux sells 56% silver for less than $20 an ounce too.

calstar 

No wonder google search didn't give results for "rolling on brazing flux" or "brazing flux application with roller"!
Thanks for explaining that.

bulgie 

Bill Davidson used to get some Japanese flux for brass that was noticeably better than Gasflux. Late '80s, early '90s. It came as a powder that we mixed with water. It was ground extremely fine, and made a white slurry kinda like pancake batter that stayed where you put it. I don't know what the secret ingredient was but it stuck really well while cooking the water out. Good heat range and wetting action for liquid brass, all the things you need flux to do, and it soaked off well too.

Unfortunately the supply dried up, no pun intended, or Davidson's connection (through Takahashi probably, or maybe Tange) stopped selling it or something. Either I didn't ask or I don't remember the answer. But one day we started using blue Gasflux brand. It was a big disappointment after being spoiled by the Japanese stuff.

I mention it here in case anyone knows what that stuff was. The words on the box were in Japanese characters (Kanji?) that I can't read. We had to buy some large amount like 20 or 50 kg at a time, but a US distributor (Nova?) could make some money selling it in smaller tubs. If it still exists and it's still as good, people would pay.

But of course the brazed bike frame biz in Japan isn't what it used to be, so some companies have gone out of business and some product lines have been dropped.

Anyone here got friends in the bike or brazing business in Japan that you could ask?

Mark B in Seattle

unterhausen

did the Japanese flux soak off easily without near-boiling water?

I'm a little curious what characteristics made it better. My main concern is that the flux comes off easily when I'm done.

In retrospect "rolling paint off a brush" is an art technique that I have heard of. But it's not stored in any neurons that are commonly fired. Probably heard of it watching Bob Ross or something

bulgie 

Yes, ISTR it was about the same as gasflux that way. This is from memory of almost 30 years ago. I don't remember the soak tank temperature, but it was in the "uncomfortably warm" range if you reached in -- wouldn't scald you. We didn't generally reach in though, we lifted individual frames out with a hook, or if there was a batch, we had a rope hoist attached to the ceiling.

The flux would soak off in cold water eventually, but steel rusts faster in cold water. We had a little Oakite in the water, weak solution but between that and the hot water, frames came out rust-free. And then went straight into an oven for force-drying.

vintage cellar

On my last frame I put some silver flux in a stainless measuring cup on a small hot plate. The flux water boils off and you're left with a thick syrupy liquid that worked well.
I didn't have to worry about trying to out-think boiling water in expensive flux paste while I inevitably watch it fall off the tubes onto the floor. Boiling water is clearly smarter than bicycle frame builders.
In the past I have placed clean aluminum sheet metal pieces under brazing areas to catch the inevitable flux fall-off for re-use. And yes, I do try slow-heating and all the other attempts to deal with
boiling water. I have largely given up with that nonsense - boiling water is too smart for me to fight.

Brass flux = Gas Flux blue works well enough for most folks. If you want utter misery, try using the powder fluxes (Brazo) offered at welding supply stores.
I haven't used the Cycle Dynamics LFB flux. Their other stuff seems to be good, and I doubt they would offer something that worked poorly.

I've used quite a few silver fluxes. Can't remember which framebuilder suggested mixing a little black flux in with the white stuff gives you some of the best of both worlds. Easier to see through and
gives you a little longer life / higher temp ceiling.

I have a lot of respect for the Gasflux company, but I didn't like (hated is probably more accurate) the regular white flux compared to Harris or (my fave ) Superior 601. Superior seemed to work well and stick better than the alternatives. System 48 flux worked well, too. I am curious about the Stainless Light flux, will order some next time I do an order with them.

One personal observation I can pass on is that choice of flux is important, but I've blamed the flux for problems that were more because of my poor technique, inadequate cleaning, or drafty workshops.
Be careful about sand-blasting with dirty media. I was using a blaster once in a shared workshop environment. Thought it was clean until I saw a guy stick a bunch of greasy motorcycle parts in there.
Keep in mind that no brand of flux is going to help you with THAT.

Small diameter silver brazing rod is a mess. 1/32" melts too quickly for anything other than really small braze-ons. 1/16" works so well for most everything for bike frames. I once tried 1/8"diameter 45% EZ-Flo silver with cadmium. Thought it wouldn't be a big deal, but it definitely took a much more concentrated effort to get it to melt compared to 1/16".

unterhausen

I'm afraid to mix fluxes because it's possible they aren't chemically compatible.

bark_eater 

Took me 30 seconds to figure this out. But Im cheating, blocking my arms into a locked up and down and then breaking the counter rotation of the fingers into 2 phase destination, a top and a bottom. Also one eyebrow has to be raised, A La Spock.

calstar 

Gasflux site lists 2 type B powders, B-1(fine powder) and Bg-1(granular powder), which is used?

thanks

Doug Fattic 

Just to be clear I use powered flux when the joint is hot and I want to add a little more. I heat up the end of the brass rod and then dip it into a can of powered flux and some attaches to the end. Then using the rolling action we talked about earlier, I keep the rod in one place (most likely it is horizontal) and roll the rod while still applying heat to the end so the flux melts off onto the metal. Probably I slide the rod away from the flame that both helps the flux to come off and not melt the rod. Of course good torch control is necessary when heating the rod up enough to begin with so the flux will stick but not so much it the brass starts to melt. And then when releasing the flux off the rod with your flame with just enough heat to again not melt the rod.

I happen to have the fine powered flux but I don't know if it matters much the way I use it. Back in the 70's when I started, brass flux came in these 1 pound tin cans that were similar to paint cans - except it also had a small 2nd hole/lid in the middle. This small hole was handy to keep partly used rods. The lid surrounding it kept junk out of the power. 40 years later I'm still using mine (after dumping out the old flux and adding powered Gassflux).