Help to make a low carat gold jewelry

[dronez]

Hi,
I need some help to make a low carat gold (about 9 carat).
I used to mix pure gold, copper, and silver together to get this.
But when I try to make a piece of jewelry out of this low carat gold bar, it break or crack easily when I hit it with hammer.
I know for sure that jewelry manufacturer has used some other metals in their low carat jewelry products...
Does anyone know what other metals that they used and what are the proportion of those metals in the mixture.

Thanks in advance for your help

 

[nickvc]

Typical UK 9 carat alloy are made up as 10% silver 45% copper 7.5% zinc th balance been fine gold.
If you have problems with cracking either your metals are not pure or contaminated or you are over working the material between annealing.

 

[Harold_V]

What Nick said, plus, if you've over heated the metal, or have melted it numerous times, it's very possible you have oxidized the base metals to the point of ruining the gold alloy. You may have to refine to recover the gold and silver, then start over.

If you did any of your work in the presence of lead, or if there was a trace of lead involved in ANYTHING that came in to contact with the molten metal, even lead fumes in the air, your alloy may be contaminated. Even a small trace of lead renders gold brittle.

Harold

 

[jimmydolittle]

Would not the piece need to be annealed after hammering to soften it again? Just asking.

 

[goldenchild]

Aluminum and indium will also make a gold alloy very brittle. They are the metals used in making purple and blue gold alloys. Respectively.

 

[dtectr]

why are you hitting your jewelry with a hammer?

 

[Harold_V]

Would not the piece need to be annealed after hammering to soften it again? Just asking.

Yes. It is a requirement, even when the alloy is quite malleable and ductile. Work hardening changes all that in a hurry. A simple heating to a dull red in daylight, followed by a quench in water (that helps eliminate scale) is all it takes. Quench isn't required--it's the heating that does the annealing, but a quench is faster, and yields a cleaner metal.

Harold

 

[dtectr]

why are you hitting your jewelry with a hammer?

i'n not kidding - i've been around custom jewelry manufacture for a couple of decades, you'll round a ring on a mandrel now and then. Even then you use a leather mallet. but lower quality/karat items should be cast en masse, with as little banging as possible.
So, why are you hitting your jewelry with a hammer?
And harold, i do believe the quench is an essential part of annealing precious metals, just the opposite of ferrous metals. The quench is only certain to remove firescale if it is a pickle, i'm pretty sure.