29 June 2012

Rolled Gold and Granulation- pt II

Back to the rolled gold wire- Mitch over at Hickoree's Hard Goods asked to make it into a pretzel pendant. 
(...gotta get me a Hill-side tie...)
Yes, the gold is a weird colour, but dont worry about it. ( its just that marble dust I was talking about)

A Pretzel Needs Salt.

So Im going to put some tiny gold granules on there.
Granulation is an ancient technique, mastered by the Etruscans. Seems to be a bit controversial as to how it actually works- but this is how it was taught to me by Dr Robert Baines:

Making the granules:
Place gold filings on layers of charcoal dust.
Heat this up, and the bits will melt into spheres; granules.
The dust helps to keep them separate. Then wash off the dust.


It'll be tricky to attach these things to the pretzel, they're really tiny. Smaller than this: "."

Ancient method: 
-malachite powder (see pic above)
-organic glue 
(Theophilus Presbyter prescribes quince pips, I think? or gum tragacanth is also good. I used a Uhu stick! Seemed to work- felt a little irreverent tho')
-flux

You paste the granules on with a little of this mix.
Heat it up gently with a bushy flame. The glue burns off ( creating a local reducing atmosphere)
Then there's this critical moment when you get a little flash of the metal just before you melt everything.
(stop before that)
The tiny amount of copper in the malachite powder melts with the gold just where the spheres meet the substrate. A very discrete join.( Is it diffusion bonding? Or is it just fusion?)

 A weird pic, yes, the pretzel is on the right with some of the granules bonded nicely. See how they are still spherical? ( bit fuzzy, sorry) Good Job!

Ironically, I decided that I was being too technical- the granules were too good, too spherical- not 'baked-in-salty' enough- so I decided to melt them in a bit, undoing my fancy-pants granulation.

The pretzel is ≈ 6mm long.
See, I told you the black stuff would come right off.


26 June 2012

Stone Rolled Wire

Awhile back I posted about the history of wire-making.
Well, I think its interesting.
Before steel tools were developed, smiths would roll a strip of gold between stones to make a 'snake',
a bit like you do with pastry or clay- between your hands.
Its difficult to do this with other metals Ive found, but gold is very malleable and ductile- so, once again, it proves to be a friend, willing to go on any adventure...

I recently completed an interesting commission- with a request for stone-rolled wire.
Here's the process. Some interesting ancient techniques used...


Here, Ive cast a long cylindrical ingot, then rolled it with a marble block on a marble slab.
(fairly frequent annealling was required) I think it took about 30 mins to roll this down to a wire.

Marble is a pretty soft stone, true, but Ive found that if the stone is too hard or too smooth, it just skids over the metal, instead of gripping it and making a nice rolling motion.
A little bit of marble dust is created, and gets rolled into the surface of the gold. Not sure what the consequences of that are- marble dust would be calcium carbonate (yes?) - so what will happen when I heat that? Black stuff? Im supposing it will just fall out, leaving a pitted surface, so much the better!
A dip into lemon juice would soon get rid of it...
In any case, the high purity gold wont be affected greatly- its non-reactive.



Dusty fingers..
The resulting wire has an interesting surface and irregular, slightly ovoid profile- not so 'perfect', but more dynamic and therefore mysterious.
It is a bit of a funny colour- dont worry- it'll come good.



Next time: what I made with the wire...






24 June 2012

Argentarius



This roman statue purports to be a memorial of Agatus, a silversmith. The inscription says, I think,
"Faber argentarius"- argentum being silver. Its interesting because he's in the middle of chasing or perhaps engraving a silver cup. The hammer has busted off- its a very finely observed sculpture, the way the hand is holding the chisel (or whatever) and steadying the cup at once, is strikingly natural, as is the likeness of the face. To afford such a thing as this, I suppose that this Agatus fellow was a wealthy silversmith?...fancy that!

20 June 2012

Bean

E grew this bean from a bean that she grew...

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?




16 June 2012

Scrimshaw


Remembered this scrimshaw badge I made, back in 2003...
At the time, Alice was wearing this at some Brunswick St. café and the waiter said "hey, you should make these and like, sell them..."
Yes...yeah...yep...

15 June 2012

Stamps

New stamps! These will enable me to produce these designs in a more consistant manner...
Rings, pendants and some coin-like badges...
Cant wait to bang these out, but because of the embossed style ( or is it debossed??)-that is, raised lettering and sunken background, it requires heaps of metal displacement. Which means heaps of force.
More than I can generate with one arm and a large hammer. Which means using Johnny The Press.
But, I have to engineer some way of holding these guys in the ram of the press. Which means making stuff on a lathe. Which I dont have. Are you feeling my pain? Does anyone get me and my 19th century problems??

6 June 2012

Bangle
































Longfellow lives up to his name, and is now a bangle too. He's a friendly, isometric sort of fellow- he keeps it simple. The latest versions of Longfellow have a ball for an eye- sort of a nod to...  Deco? Mid-Century? Memphis? Spheres?


( p.s. Im working on improving The Golden Smith Shop- please excuse that it looks like a molting penguin?... no lets say "immature eagle"...)

1 June 2012

Gold Anew


Sunrise Ring in Recycled 14k yellow gold.

There was an ancient tradition that you would bring three silver coins to the jeweller;
two he would melt down and make into a ring- and one he kept as payment.

Recently a customer sent me some gold jewellery to be melted down and transformed into a new Sunrise ring. You might like to do that too. There is a very significant saving on material cost to be had. Contact me for details.