Q: I’ve been told that acetylene was necessary for jewelry soldering, because natural gas and propane just don’t get hot enough. Is that true? Would I need oxygen to use anything else besides acetylene?
A: You don’t need to use acetylene, or oxygen either. While most folks using natural gas these days do so with oxygen, in order to use the torches (Meco, Hoke, Little Torch, and others) designed for that combination of gases, there are many fine metalsmiths who’ve done a lot of great work using just natural gas and compressed air. And sometimes that compressed air is supplied by just blowing manually into a tube on the torch. Such torches take a bit longer to learn to use, but the people I’ve seen who use them, swear by them (not at them). They give instant control over changing the flame characteristics more easily than by adjusting the valve on a torch.
I remember visiting a number of the finer workshops in London in the late 70s, and in one, where they had just finished winning one of the Diamonds Today Awards (or something like that) with one of their 18K gold pieces, everyone used the mouth-blown torches. They had an oxygen/gas torch over at one side bench for when people needed higher heat, but at the main workbenches, it was just the gas lines, and tubes with a mouthpiece for the air on the torches, and they were producing world-class jewelry.
In my first jewelry class, back in high school in ‘68, the studio was equipped with natural gas and compressed air. I seem to remember the torches were the “Hi Heat” brand, or something like that. You can still buy them. For general silver fabrication, they work fine. Most compressed air/gas torches use a wider tip with multiple orifices, and give a fairly large, brushy flame, rather than a single-center pinpoint flame. It’s when you get to needing tiny flames that are good and hot, or need to melt more than solder, as in casting, platinum work, or much gold work, then most of us prefer oxy/gas.
In short, while most of us are using oxygen, not compressed air, to say it’s not hot enough is a matter of preference, and what one is doing Also, if someone typically uses an air-acetylene torch like the Prestolite or Goss, the flame she’s used to is hotter than that she’d get with air and natural gas, but not as hot as what she’d get with oxygen and natural gas. I can easily work platinum, even melting and casting it, with natural gas and oxygen. I certainly can’t do that with a Prestolite. Of course, if she’s using acetylene with oxygen, then you’re right; natural gas and oxygen will be a good deal cooler. Probably, she’ll prefer it unless she’s using a Little Torch and is addicted to the smallest two tips, and maybe the #3 as well, which are really only useful with acetylene and oxygen, or hydrogen and oxygen.
by Peter W. Rowe M.F.A., G.G.