Working with gold questions

[TeeDee]

Apologies in advance if this thread leads me to ask many further questions.
I have recently been asked to take on a few small commissions in gold some simple and some less so.
I'm reasonably familiar now with working with 925 silver but the more I research gold the more I find a staggering array of carats, colours and differing properties even within these groups.

So 2 initial questions:

Annealing: I have recently aquired Mark Grimwade's excellent 'Intro to precious metals' which seems to indicate water quenching at close to annealing temperature for 18ct and lower coloured golds presumably yellow and red?? ( pg153 in my book). Most other sources seem to suggest air cooling to black heat before considering quenching. Have I misread the book or am I missing something and is there a generally accepted method.

White gold solder: I have been asked to make an 18ct white gold ring in approx 2.3x2.3mm square section. I will be rolling from 3x3 to get the correct dimension and intend to fabricate from 18ct high palladium content white stock. Given that Cookies and Betts don't sell white solder wire I will need to buy a complete 2gm panel. Is there much colour difference between hard/med/easy as there is certainly a cost difference. Also are there any problems I should anticipate as I have not worked white gold before.

Any advice appreciated
Tim

[Dennis]

Advice on annealing various metals can be confusing. But the choice is mainly between, 1.air cooling until the colour goes and then quenching, or 2.quenching from glowing.
In my bumbling amateur way, I try method 1 first and if the metal remains hard, I go on to method two.

The rules worth noting are:
Only heat to a very dull glow and don't re-anneal until a substantial amount of work hardening has occurred.

Regarding solder, the harder it is the closer the colour match. If your joint is neat, then hard or medium should blend sufficiently. Even multiple soldering rarely requires more than two grades in all, because solder re-melts at a higher temperature, so you can use the same grade two or even three times in a row. Dennis.

[ps_bond]

On the slightly over-technical side, some alloys of white gold may form brittle intermetallics when fused with other metals. This requires some careful temperature control and forging to control them - and there's very little around in print specific to jewellery metals. It'd make a great research project, but on the materials science side rather than jewellery.

[TeeDee]

Advice on annealing various metals can be confusing. But the choice is mainly between, 1.air cooling until the colour goes and then quenching, or 2.quenching from glowing.
In my bumbling amateur way, I try method 1 first and if the metal remains hard, I go on to method two.

Hardly amateur Dennis. Sounds more like very sound methodical approach which I will be following. Thank you.


On the slightly over-technical side, some alloys of white gold may form brittle intermetallics when fused with other metals. This requires some careful temperature control and forging to control them - and there's very little around in print specific to jewellery metals. It'd make a great research project, but on the materials science side rather than jewellery.

I enjoy the technical side Peter as the more I understand, the better I feel equipped to tackle problems as they arise. Sad as it may seem, my new 'Grimwade bible' sometimes comes out for a bit of light bedtime reading although I have to stretch my memory back a bit to material science lessons at engineering college to recall some of the terminolgy. You're right about the lack of technical info. The most I can find is basic but useful info in Cooksons big book.

Since you mentioned different alloys, have you or anyone else ever come across odd effects when melting down gold scrap? I had some 9ct rings to melt to make one larger one. I also added a bit of my own scrap including a very small amount of unmarked but locally tested at 14ct. After casting into a small ingot I rolled it to 7x1.8mm. The metal,seemed incrediby hard and my first attempt at soldering using 9ct hard solder resulted in melting the ring! It was almost a though melting point of the alloy had decreased to that of the solder. Had to re melt and roll. Any further attempts with hard solder ended with a brittle joint or the possibility of a melt down again. Finally used easy solder today which seems to have done the trick although I'm not sure if it will stand a significant stretching. The metal also has a bit of red streaking in it which I assume is copper separation.
Any thoughts?8597859985978599