[TheForge] Re: Flux, was rust & pickling

Tue Aug 19 14:50:00 2003

This subject seems to come up repeatedly.  I don't know specifically
about borax, but most inorganic chemicals start releasing their water at
temperatures much below their melting points.  Working at about 350 in a
standard oven would probably suffice.  Again, I haven't tried this with
borax, but I'd suggest trying it before going to higher temperatures or
melting and regrinding it.

Many anhydrous chemicals, probably including borax, will absorb water
from the air.  However, the simple expedient of keeping it in a closed
container will protect it from air.  The short time it is open for use
will generally not result in a massive uptake of water.  I'd suggest you
keep your anhydrous borax in a large jar, and pour it into a smaller
jars for use.

Bruce
NJ

>>> [email protected] 08/19/03 12:45PM >>>

> So are you telling me that melting borax on an iron cookie will pick
> up some of the iron?

Following up to my own post...

How do you melt borax on a cookie tin?  The melting point is around
1500F, a red heat.

Checking in the handbook, borax loses 8 of its 10 bound water
molecules at 140F and the rest at about 400F.  But it doesn't melt
until waayyy hotter than that.

I never tried to dehydrate borax in the oven at, say, 450F.  I melted
some up last night over the forge in a cast iron ladle (kinda messy),
poured it into a cast iron bowl where it turned to black glass.  Broke
it up into pea size, then ran it through an old manual meat grinder
with the hamburger die modified to be more like a grain grinder.  Nice
powdery stuff that should be good for flux.

Someone said that anhydrous borax will quickly re-absorb water from
the air.  I think a maybe the advantage to bothering with melting and
grinding the borax is that in the glassy state it doesn't do that very
readily.

Just 'spearminting around...

- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 

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http://home.tallships.ca/mspencer/						
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