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Thread: Brazing flux

  1. #1
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    Brazing flux

    Since I've gotten back into some welding and cutting I've had the need to do a little brazing, I have a couple of pounds or so of unfluxed rod which is by far my preference so I thought I'd grab a can of flux so I swing by the lws and grab a can and some electrodes, I was more than a little shocked at the price of a small can of flux, 18 bucks for I think a 1 lb can, I think it was Harris, it was blue. I told them to keep it & I'll go back to Borax, got a big box of Borax for 4 or 5 bucks, Ive used it and Boraxo hand soap for years. A couple of days later I was at TSC and they had Forney brand for 7 bucks, gonna stick with the Borax for now, heck a pound will last for years for me. I hate the prefluxed rod seems like there is always too much flux and it's hard to manage. Did a couple of joints yesterday with the Borax and some 1/8th" rod & it did great.
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  2. #2
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    Re: Brazing flux

    some flux is designed to mix with water and be sticky so stick to part. might be waterglass or sodium silicate mixed in with the borax.
    .
    often prices for stuff is like $200. for 1 gallon container and $300. for a ton on a pallet. cost is often somebody dealing with putting it into a small container and labeling and of course making a profit. pollution control requirements from EPA can drive cost up. equipment for dealing with chemicals needs cleaning before other chemicals are put in equipment.
    .
    just saying its usually cheaper by the ton but who needs a ton of flux ??

  3. #3
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    Re: Brazing flux

    use a mix of borax and boric acid in a 50/50 mix with some water to make a paste, works much better than just borax alone...both are cheap

  4. #4
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    Re: Brazing flux

    X2 on borax and boric acid. I often dip the heated rod in and it glazes over /sticks to the rod

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    Re: Brazing flux

    For SiB, I just use straight 20 Mule Team Borax. Heat the rod, dip it in borax, which melts onto the rod, and go. Works great.

    If the metal I'm using is super dirty, I'll sprinkle some borax onto the metal and melt it on. The borax really pulls the crud out.

    I bought some fluoride-based flux for silver soldering/forge welding, but I've never had to use it.

  6. #6
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    Re: Brazing flux

    When I first saw the price on the flux my first thought was "silver solder flux", but nope plainly marked for brazing, I may try the boric acid, water & borax mix. I always used regular flux when I was a kid until I ran out, then someone told me about the borax, long story short I didn't have borax, but we always had boraxo so I nabbed it, it worked ok, but not as good as flux or borax.
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  7. #7
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    Re: Brazing flux

    I use white coat Harris in 3/32. Thats it

  8. #8
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    Re: Brazing flux

    Caveman,
    Before his unexpected departure,HT and I were working on a brazing thread and did a fair amount of research so we could clarify some of the wives tales surrounding the topic. I was never able to find the exact ingredients that go into the store bought flux. The closest I could come was the MSDS for the Harris LFB (copper based brazing fillers). They call 66% borax and boric acid with the remainder being “proprietary ingredients”. By proprietary I would guess they mean some types of de-oxidizing and other cleaning agents, but for all I know they may mean “Eye of newt, Unicorn tears, and Teeth of chicken”.

    Harris does say their flux may be mixed with distilled water and applied as a paste.

    As for the price? I have a fresh quart can of blue Smiths I purchased at the LWS several years ago and a quart can of Harris/Welco600 that I picked up at an estate sale for a $1. Guess I’m fixed for the rest of my life and whoever buys my stuff when I’m gone won’t need to buy any in their lifetime either.
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  9. #9
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    Re: Brazing flux

    Iíve used pure borax on production brazing
    of steel wire and Iíve used several commercial
    brazing fluxes (like Brazo) for repairs. Iíve
    developed an opinion (not based on any
    real side by side comparison) that the
    commercial fluxes work better. There seems
    to be better wetting action of both the flux
    and the filler.
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  10. #10
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    Re: Brazing flux

    We had a can of Brazo around the house for years as a kid it got replaced by a blue flux, Harris I think, I didn't like it as well.
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  11. #11
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    Re: Brazing flux

    I just posted this picture on another forum not long ago. Mentioned it looked like a iron forging flux? I've only gas welded and played with flux in school 100 years ago, I don't know much about it. Anyhow I found this in a old Kennedy tool box I bought at auction.

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  12. #12
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    Re: Brazing flux

    I use ammonium chloride(sal amoniac) when remelting and mixing my tin alloys.

  13. #13
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    Re: Brazing flux

    After using bare rods and canned flux for 30 years,I couldn't find bare rods locally so I bought fluxed Lincoln rods. I wasn't able to do a satisfactory job with the fluxed rods. It wouldn't flow out like I am accustomed to. I ordered one pound on Ebay from China for $1.89 + .50 shipping but haven't tried it yet. I'm not making any bets but if the rods suit me I'll try their innershield wire and stick electrodes.

  14. #14
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    Re: Brazing flux

    Quote Originally Posted by Jax View Post
    After using bare rods and canned flux for 30 years,I couldn't find bare rods locally so I bought fluxed Lincoln rods. I wasn't able to do a satisfactory job with the fluxed rods. It wouldn't flow out like I am accustomed to. I ordered one pound on Ebay from China for $1.89 + .50 shipping but haven't tried it yet. I'm not making any bets but if the rods suit me I'll try their innershield wire and stick electrodes.
    I know what you're saying about the prefluxed rods, something just not right with em, like the alloy ain't right. I think I can still buy bare rod at my LWS if I can afford it, unlike their flux. LOL
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    Re: Brazing flux

    if you're not too picky on the alloy check out local scrap yards, I know the scrap yards around here get lots of just old rod that was laying around for fifty years.

  16. #16
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    Re: Brazing flux

    The prefluxed rods seem to all be LFB 15 alloy which is more for “braze welding” where you want to build it up. LFB 15 doesn’t wet out as well as just plain LFB, which is superior for drawing by capillary action.

    I use Harris rod and it is clearly stamped similar to TIG rod. Old rod wasn’t individually marked, so you had to keep the rod boxes separated. A few years ago I bought about 5 lbs. of “bronze rod” at an estate auction. Fortunately I know the way the rods should wet out and flow so sorting it out wasn’t a big deal. It’s worth mentioning that old rod that has been kept in an open environment will tarnish which is an oxide coating. I polish it of with a clean Scrotch Brite pad before using it.
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