[TheForge] Forge welding

[Jerry Frost]

Borax is hydrophilic meaning it'll absorb water if it can and lock it in 
untill driven off. This is called hygroscopic water and is easily driven off 
at 230*f. We had to deal with hygroscopic water content a lot in the soils 
lab.

If you're going to melt in a dipper in the forge anyway, just use it as is, 
molten it won't foam and works just fine. Except for one small detail, the 
foaming action drives it into the smallest opening making for better fluxing 
than non-foaming. I secure the parts at the join well enough a little 
foaming doesn't move anything.

No flux needed at all if you want to go through the labor to prepare, heck 
you don't need heat, room temp works fine. All you need to do is match the 
surfaces so there're no gaps between them, polish both to a high sheen, a 
drop of oil will keep them from rusting but that probably qualifies as 
fluxing so do't cheat. Clamp the join so it won't move, give it some time 
and they'll be welded. This is a cold difussion weld where a forge weld is a 
hot diffussion weld. Heck many asteroids are cryogenic diffusion welded 
piles of metalic rocks. Anyone here who's a machinist and had someone lay 
their gage blocks together or stacked knows cold diffusion welding well. Dad 
kept his "Joe blocks" wrapped in oil paper to prevent it.

My welding preference/technique/style/? is to match the surfaces, touch them 
to the belt sander or draw file to clean and sprinkle a light dusting of 
flux then secure, heat and tap lightly to weld. I use more force refining 
welds if necessary but that's all it takes in my naturally aspirated propane 
forge. My flux is 1pt boric acid to 4pts. borax and works a treat.

I've seen numerous videos, Youtube and others, showing 3rd world smiths 
working and it seems most use charcoal from the fire they chew and spit on 
the join. In the videos anyway, they always get a good weld. Some are using 
sand or thin mud as flux. The sand seems intuitively plausible and has been 
done for centuries but spitting mud on the join seems a stretch to me. 
Still. . .

Jer
----- Original Message ----- 
From: "Mike Spencer" <mspencer at tallships.ca>
To: <theforge at mailman.qth.net>
Sent: Tuesday, July 26, 2011 8:19 PM
Subject: [TheForge] Re: Forge welding


>
> Roger Degner wrote:
>
>> I use anhydrous boarax which comes from a chemical supply house not
>> 20 mule team that was boiled and then ground which still has water
>> in it or absorbs water.
>
> Laundry borax -- the 20 Mule Team stuff -- contains 10 (!) molecules
> of water for each molecule of borax (sodium tetraborate) as "water of
> hydration".  That is, it's not wet or even slightly damp in the usual
> sense.  The configuration of the borax molecule is such that those
> molecules of water bind to it very tightly even when the borax seems
> to be powdery dry.  Toasty-warm won't drive off that water but the
> temp of orange- or yellow-hot iron will.
>
> When you put such hydrated borax on a piece of hot iron, it writhes,
> froths and foams as those 10 molecules of water are driven off.  Maybe
> that doesn't matter if you're welding anchors or axles but for
> smallish or very delicate work, lots of the borax just falls off (into
> the fire if you apply it with a spoon in the fire) and fails to melt.
>
> I put a bunch of 20 Mule Team borax in a long-handled iron ladle and
> melt it in the forge.  As the water is driven off, I add more borax
> until the ladle is half full or so. Then I pour the melt out onto a
> steel slab where it hardens into a brittle, greenish-black, glass
> puddle.  Break it up a bit with a hammer and run it through an old
> food grinder to get a gritty powder of -- ta-DAH! -- anhydrous borax.
>
> That powder sticks to hot iron real good, melts quickly at orange heat
> and wicks into joints pretty well.  Doesn't foam and froth.  And
> it doesn't seem to pick up water from the air, either, so it keeps
> indefinitely.
>
>
> FWIW,
> - Mike
>
> -- 
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                           /V\
> mspencer at tallships.ca                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^