18 June 2012

Natron Flux

Metalworking can be pretty tricky.
How did people even discover how to do it?
Mostly by accident or serendip, we might say.
What impresses me is that we solved many problems without knowing the complex science behind it.
(In keeping with that, I will try to keep this discussion very simple)

For example, you can join two pieces of metal together by introducing another metal that has a lower melting temperature.
But when you heat certain metals in a flame, they get black on the outside.
(a reaction with oxygen in the air)
This black stuff prevents the joining of the metals.
So someone discovered a way of solving this problem- and today we call it Flux. (latin for flow)
Flux is a substance that you paint on to the metal, and as you heat it, it melts and becomes like a glassy coating that creates an oxygen-free world on the surface of the metals. No more black stuff- and everything flows.

Today, goldsmiths tend to use Fluoroborate flux. It works well, but folks, the vapours are bad for you to breathe in. Be sure to read the safety data if you use it.

Before that (and still), most would use Borax flux (sodium borate) which is a naturally-occuring mineral.

It is sold as a sculptural cone-shape, which you can grind up and mix with water to make a paste.

It doesn't work as well as, and is harder to remove than Fluoroborate flux but its slightly less harmful, I gather. Still, read the safety data if you use it.

Seeking an alternative, I had read that the ancient Egyptians used something called "Natron" as a flux, so I thought Id look it up, wondering about its toxicity. Might it be a viable alternative? Not that I think ancient Egyptians did things better- I mean, they worshipped flies and reportedly, would treat wounds with faeces. But still, I'd like to know more about Natron.

Historical Natron (sodium carbonate decahydrate and sodium bicarbonate) is a naturally occurring mineral that can be gathered from dry lake beds. In fact, there is a lake in Tanzania, called Lake Natron. (There is a Lake Borax too...)

Apparently this pink lake is an important Flamingo breeding ground - lots of pink!
Natron was a very useful substance in the ancient world; used in soap, mummification preservatives and glass making and so on.
Turns out Sodium's elemental designation; Na, is related to the egyptian word natron.

Where can I get some? Lake Eyre perhaps?
Does it work as a flux? Are the vapours toxic?

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