black goo appearing in flux. gasfluxer suspected.

[pereiracycles]

Something strange is happening while brazing lately. Occasionally, just as the flux becomes fully active, a black contaminate appears. I don't think it's the flux burning. Has happened with both silver (white) and bronze (type-g) fluxes. I'm running a gasfluxer. The only thing I can think of is that the gasfluxer is doing something weird. I've heard of the gasflux breaking down the hoses--is this symptomatic of that? I'm cleaning my tubes better than I ever have before, so I'm pretty sure it isn't that.

Any ideas?

Sorry I don't have pictures. I'll work on it.

Thanks,
Tony

[pereiracycles]

I meant type "B" bronze flux.

[pereiracycles]

Here's a picture:
Black Goo in flux | Flickr - Photo Sharing!

When it happens with bronze it is much worse.

[zank]

I don't have a gasfluxer, so I can't speak to how that might be affecting things. But one thing that comes to mind is I sometimes notice that if my flame drifts from neutral to oxidizing due to the bottles being depleted, the flux activity really picks up as it wards off the extra O2. The flux can go black as it's capacity is used up.

[pereiracycles]

Zank,
Thanks for the reply. The gasfluxer is sort of new to me and it throws off the color of the flame so much that it is hard to see the secondary cone. I might be running too far on the reducing side, but not likely oxidizing.

[Dave Kirk]

I would guess it to be either some contamination coming form the material or rod or............... some old goo being in the gasfluxer. In time condensation will get in there and bad things can happen. Have you pulled the unit apart to clean and service it?

dave

[e-RICHIE]

Zank,
Thanks for the reply. The gasfluxer is sort of new to me and it throws off the color of the flame so much that it is hard to see the secondary cone. I might be running too far on the reducing side, but not likely oxidizing.

you are (running it too far on the reducing side) atmo.
turn up the heat and work faster.
trying to finesse the filler metal and respecting the low temp alter is the enemy.
big tips. hot flames.
make the parts respect your skills and follow your lead.

[pereiracycles]

Dave,
I've had the gasfluxer for less than a year. It was serviced just before I bought it from Sacha White, so I know it came to me in good shape. I'll look inside and see what I can find.

Richard,
I run a pretty hot flame (much hotter than I used to) and have never had this trouble before. I may still be one of the new guys, but I've built a lot of stuff in the past 7 years. Seems strange that this would crop up suddenly after years of nice clean brazing.

[e-RICHIE]

Richard,
I run a pretty hot flame (much hotter than I used to) and have never had this trouble before. I may still be one of the new guys, but I've built a lot of stuff in the past 7 years. Seems strange that this would crop up suddenly after years of nice clean brazing.

you mentioned the reducing flame. when the acetylene cone gets enveloped in the flux,
this will happen atmo. i've had my gasfluxer since the carter era and have never cleaned
it or maintained it. all i do is top off the liquid when the level drops down.

[pereiracycles]

I'll play around with it and see if I can make it happen at different flame settings. Thanks for the advice.

[Eric Estlund]

Side bar- I ended up running a splitter at my regulators and have dedicated silver and brass torches with only the brass lines running through the Gasfluxer. In a pinch the "juiced" torch works fine for silver, but the pure gas seems to work better for silver with type U.

[Eric Estlund]

PS- A #4 lens really helps me see the flame zones. Running darker with the GF helped save me some strain and kill the "Gas Flux Green". Some folks find that a little dark, but I love it.

[pereiracycles]

Ok, I just did some experimenting. Looks like I was allowing the flame to go a little too far on the reducing side. Because of the intense green gasflux flame I wasn't reading the flame right. Just now I ran some fillets through a range of torch settings and the "goo" appeared when the oxygen was turned down to far. Flame size didn't matter, just mix ratio. I noticed last week that my acetylene regulator was set around 10 psi, where I usually run 5, so maybe that had something to do with it as well.
Eric, I might bump up to a #4. I have always used a #3, but it seems a little light with the gasflux flame.
Thanks to all for the advice. I believe the problem has been solved.

[Dazza]

I know you fellas like Gas Fluxers
but I have never understood the need for one

why do you use one?

I always thought that maybe fillet brazing may be sweeter, is this so?
but why the expense/complication for lug brazing and other little braze ons?

[Eric Estlund]

It pushes the heating cycle (small benefit) and is helpful for utility brazing sans paste flux. This is handy for tacking, spot fills, etc. It is nice for fillets, but not essential. I like the redundancy. I don't use one for silver brazing- GF brand liquid flux isn't even really effective at silver temps. In a past life I have built a few thousand bikes with fillets and braze ons and nary a swipe of paste flux, albeit generally on slightly thicker tubes. Part of the reason I own one is because of this- I got used to it.

All of that said- for new folks looking at buying one there are better ways to spend a few hundred bucks of start up scratch, and the green bright flame isn't super helpful in figuring out how to braze, steel heating colors or when paste fluxes become active/ useful/ burnt.

Like any tool it's only truly useful when it is used appropriately.

[pereiracycles]

I'll Echo what Eric said. Fillets do lay out a little sweeter. Since I build mostly using fillets it has been a nice addition. Lately I discovered I can build racks without any paste flux. This is really helpful since I usually add a strut, fit the next, braze, fit a light mount, braze, etc. Sometimes the paste would have to be soaked off in between these steps and not using it has sped things up nicely.
I've been pretty happy with it, but I do find that I need to wear a respirator or I get a sore throat. This alone may stop me from using it someday. For now I like it.

[steve garro]

I have brazed everything I have brazed with one, I never adjust the settings for any filler/flux or anything.
When I see some of the flux mounds used by some I know why I use one - less muck.
As Tony says you can braze small stuff 0 flux no sweat.
It seems like you can really push the boundaries of heat at the hot end & get optimal washout at the edges without charring, and this is what speeds up fillet cleanup.

different strokes - Garro.

[Dazza]

fair enough answers

[Brian Smith]

It pushes the heating cycle (small benefit) and is helpful for utility brazing sans paste flux. This is handy for tacking, spot fills, etc. It is nice for fillets, but not essential.

Do you tack without flux? I don't think the flux is ever a hindrance to brazing, is there something beneficial about not using it?

Tony, glad you got it sorted.

[Eric Estlund]

Without paste flux? On occasion- though not generally for bike tubes. I do however tack with way less paste flux then many people. I preload the insides of tubes, but don't generally slather it on until I am ready to do the actual structural joint (and even then I usually don't use as much as some folks).