[Sca-cooks] Off Topic: Bleach replacement?

[Stefan li Rous]

> > How does it help in the welding process? I'm only familiar with its 
> uses
> > as a laundry and personal-care products additive and as flame 
> retardant
> > for fabrics (and for getting dumped out of airplanes)...(oh, wait, I 
> may
> > have answered my own question....does it affect the heat of the 
> items in
> > some way?)
> > --maire, itching at the thought of all that borax (I'm really 
> allergic
> > to it from years of over-exposure at a job)
To which Phlip replied:
> It melts all over the piece you're working on, and prevents the oxygen
> from burning the metal. At the temperatures I work at when welding in 
> the
> forge, the metal will actually catch fire and burn, unless you protect 
> it from
> oxygen. If you do protect it, however, you can weld two (or more) 
> pieces
> together as solidly as if they were from the same original piece of
> steel.

To elaborate a bit on what Phlip said. Burning is just the most extreme 
situation. Oxygen can cause problems with welding iron well below that 
at which the iron burns. At temperatures below the conditions at which 
the iron will burn, like most metals will, the iron will still oxidize. 
Same process just not as spectacular. The problem with oxidation is 
that it forms a layer of iron oxide (rust) on the iron and this layer 
prevents the two, not quite so solid, pieces of iron from easily 
melding into one piece, ie welding, together. The borax as well as 
sealing out the oxygen, also acts as a flux or cleaner. Any surface 
impurities on the surface of the iron will tend to float on the borax 
and thus this will get them out of the way from where they would also 
interfere with the combining of the two metal pieces.

Aluminum is even more reactive with oxygen than is iron. Most aluminum 
that you see already has a fine coating of aluminum oxide on it. This 
is one of the reasons that aluminum is so difficult to weld. Borax will 
not work as a flux for aluminum. Usually special equipment is needed to 
exclude the oxygen in the air from the hot aluminum, often a 
non-reactive gas of some type such as helium.

You can see iron burn for yourself though. Pick up a wad of steel wool 
and touch a lighter to it or stick it in the flames of a gas range. In 
this case the iron filaments are thin enough that they can locally 
reach the temperatures that Phlip was speaking of, and "burn".

Stefan
--------
THLord Stefan li Rous    Barony of Bryn Gwlad    Kingdom of Ansteorra
    Mark S. Harris           Austin, Texas          
StefanliRous at austin.rr.com
**** See Stefan's Florilegium files at:  http://www.florilegium.org ****