Q: I’m looking for a small torch for silver soldering. Will one of those inexpensive butane torches work okay? Or what about one of those propane torches that screw onto the top of a gas cylinder?
A: The butane mini torches will do small modest jobs in silver, but are only barely hot enough in my experience. Some are better than others. The Ronson Multiflame (I think that was the name) that I had years ago was considerably larger in flame size than, say, the smaller “Blazer” style ones one sees today, and I’ve seen even smaller “pencil” styles ones that are likely good for lighting a cigar or a fire in the fireplace, but won’t solder much more than small wire-work joints. so it depends on just what butane torch you’ve got, and what you’re trying to do. The fuel itself burns a bit cooler than does propane, but more important is how much of it the torch is burning at any one time. Many of the current crop of small hand-held butane torches are just a bit too small to be really useful.
But propane and air does work just fine, though not with the pinpoint control you may be used to with propane and oxygen. Any local hardware store will happily sell you a propane plumbers’ torch that uses disposable small tanks. These are relatively safe to use and store, and are hot enough for decent jewelry-scale soldering, though again without quite the pinpoint control you may be used to. For silver, though, with its high heat conductivity requiring you to heat a wider area anyway, they can do just fine, once you get used to them. A refinement of this type of torch adds a hose between the torch handle and the tank, and this may be the better type for you, since the flame won’t change from tilting the torch.
My personal choice for your situation would be to go with air—acetylene, however, You can get either the somewhat larger B size tanks, which will last for a very long time, or the smaller R (I think that’s it) sized tanks, and hook this up to a Smiths Handi Heat, a Prestolite, or some similar air-acetylene torch, and you’ll have few limits on what you can do. With larger tips, these can melt significant amounts ot silver, and with smaller ones, do fine wire soldering. While acetylene means storing another tank, like propane, it’s a low pressure tank without the high pressure dangers of an oxygen tank, and in case of a leak, it dissipates very rapidly, unlike the much more dangerous (in my opinion, at least) propane, which is heavier than air and tends to pool in low areas indoors.
Another choice worth considering is a Little Torch. While normally these get used with larger tanks, you can get this with adapters and regulators that fit the small disposable propane tanks, as well as similar-sized disposable oxygen tanks. These small tanks are pretty safe, simply because the small amount of total gas they contain. They’re more costly because buying gas in those small disposable canisters is hardly economical, but it does give you a very small, relatively safe package with which you can do occasional soldering, and if you’ve a preference for a very small precise torch, the Little Torch of course is an obvious preference. At one time I was doing art fairs and the like and desired some means of sizing rings on the spot for customers. That setup worked just fine for me then without needing a lot of space in the car to transport it.