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Heating gold vs sterling


#1

I received a request to make a white gold ring. Ive only done sterling silver. Ive seen that heating gold, you put the flame directly on the joint instead of heating the entire piece. Is that correct?


#2

I was very nervous to work in gold for the first time and I had the same question, namely, is it very different to silver. I found that it was not really, and you can concentrate the heat on the joint only with gold. I believe that this is because silver is a better conductor of heat than gold, which is why with silver you need to heat up the whole piece. If you only heat the joint the rest of the piece would suck away the heat and your joint would not get hot enough. With gold the thermal conductivity is less which is why you could heat the joint only. The usual rules for soldering still apply, ensure you have clean metal, and clean solder and use flux. I believe there are special fluxes for gold, I use a universal flux which works too. Oh yes, make sure to match the colour of your solder to the gold, solder is available in different karats and colours. Good luck.


#3

Thank you so much for your reply. Ive heard that you should also heat your flux on your piece first to form your normal white film. Is that pretty accurate when joining gold? White gold will solder the same as yellow, correct? Or is there a special exception for wg?


#4

Not sure how to accurately answer, not enough experience with different gold sorts. I wouldn’t think there is very much difference between soldering the gold sorts. The proof is in the pudding and simply try soldering on practice pieces till you feel comfortable. Heating the flux till it stops bubbling with allow you to place the solder without it jumping off.


#5

If you can silver solder you can gold solder. Silver soldering is much less forgiving than gold soldering.
Silver like copper takes a lot of heating. The entire piece has to get hot before the solder will flow. That’s why we use a heavier paste flux on silver than on gold.
In silver soldering it’s useful to coat the entire piece with a 50/50 mixture of denatured alcohol and boric acid to help reduce fire scale. the seam is fluxed with a paste flux. I heat the entire piece with a neutral flame with a tiny bit of red just beginning to show at the tip of the flame. Less oxygen less oxidation. When the flux runs clear and like water then I dial in a bit more oxygen into a tighter and hotter flame and focus on where I want my solder to flow. I like to pick solder and add the solder at the last second so that it doesn’t just sit there and boil while heating the whole piece. Over heated solder will have pits in it where the lower temp alloy is burned out.
For gold soldering I also coat the metal and diamonds with the boric and alcohol solution. I never ever put it of corundum. Sapphires or rubies. It will ruin them. Under heat the boric acid will bond to the surface of the stones and when pickled afterwards leave pits and a rough surface on the stones.
With gold soldering many folks use a more watery liquid flux. It’s fine for 14kt and higher. 10 kt will need the paste flux. Unlike silver soldering the entire piece does not need to be heated as much. Some general heating but mostly I focus on the seam. You can pin point solder on gold. This is why it’s much easier to build up worn gold crown tips in gold without worrying about the solder that is holding the crown in place melting and having the crown fall off. Also the tolerances for seams being tight while soldering are not as close for gold as for silver. You can actually kind of fill in gaps. Not much but way more than silver.
Again I pick solder gold as well. I hate over heated solder and the ensuing pits.
Yellow gold can be quenched while warm. Nickel bearing white gold will get really hard if quenched hot. Which can be a bad thing or a good thing. If I am making a plunger on a clasp I quench so that it will be nice and hard and have a bit of spring to it. Otherwise air cool. Red and rose gold must be quenched while hot or it will get very brittle. See the MJSA Journal for July for an article on rose golds for more info.
Have fun and make lots of jewelry.
Jo Haemer
www.timothywgreen.com


#6

Thank you Jo for that very valuable information! Would you suggest I use paste for 10k?


#7

Yes. Use paste flux on 10kt. Stainless steel too.
Jo


#8

Thank you Jo! You’ve been a great help! I definitely feel more confident in starting out with gold soldering. I’ll definitely keep you all updated with my progress


#9

Well, here’s my 1st attempt at soldering gold. I left it unfinished as its still scrap and would like to keep as much metal as possible. I cut the band and resoldered it closed. I actually ended up using wire solder as opposed to paste or sheet since that’s the type of silver solder I use, plus for the amount I got, it was a less expensive investment in case my attempts failed. But im happy to report that it was a success! Thank you all for your advice!