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[DPRG] Making Metal

Subject: [DPRG] Making Metal
From: Patrick Innes kc5ugq at yahoo.com
Date: Wed Oct 18 10:12:31 CDT 2000

> As I started to pour into my mold, I finally
> understood what "dross"
> was all about.  Probably 3/4 by volume of what I got
> out of my 
> crucible appeared to be junk floating on top of a
> little pool of
> shiny liquid aluminum

In my previous reply, I mentioned using an argon
atmosphere to exclude oxygen.  I was having a no-brain
moment, as there is a much easier way to do this:

Borax, as used in laundry booster powder, makes an
excellent flux for forge-welding, as well as casting. 
Sprinkle a small amount of it on top of your "charge"
as it just begins to liquefy, and it will melt,
forming a barrier against oxygen penetration, and
preventing dross formation on top of the molten metal.

Expect some sizzling and "foaming", as there will be a
small amount of water in the borax powder, that will
have to boil off (You _have_ been wearing eye and skin
protection, right?).  It will melt to a glass-like
layer on top of your metal, and will then proceed to
just sit there, keeping the oxygen out.  

You'll want to keep this stuff from leaving with the
metal when you are ready to pour.  I think you should
be okay just skimming it off the top, since a slow
pour will allow the metal to leave the crucible under
the skin of flux.  If any comes along for the ride, it
will probably want to float on top of the metal, being
lighter than it anyways, so you should be okay.

I don't usually use flux much, except when welding at
the forge.  I'll ask my friend for more details, and
let you know what I learn.

-- Patrick

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