I have been a mount maker for the past 6 years and have been learning to introduce new practices and schools of thought into my techniques. I've always used a Smith's Little Torch oxy/acetylene rig for my brass brazing needs. Only recently was I introduced to using a bernzomatic with mapp gas for this and honestly, I've had varying degrees of success with it. It's great if you need to anneal a large swath of metal, but it's fairly limited in it's ability to braze small joints. The flame is simply too big. I've been trolling the inter-webs looking for a pencil tip/jeweler's torch set up that is as compact and cord free as the bernzomatic is, but all that I have found are butane and propane based. I am currently in the process of doing the research to find out the burning temperatures of the various flames discussed and what the suggested temperature for soldering two pieces of brass together using safety silv 45 might be. There seems to be a lot of conflicting information out there but from what I have gathered, acetylene burns the hottest, about 2500 Celsius (combustion with air, as opposed to oygen), Mapp is about 2010 (with air), and both butane/propane are around 1970 degrees Celsius (with air). All of which is more than hot enough to melt the Harris Brand SS-45 at 663 degrees Celsius. Interestingly, Harris suggests using their safety silv 15 for brass to brass joints. The Harris White Stay Silv flux is active between 565 and 870 degrees. They offer a ton of PDFs here. http://www.harrisproductsgroup.com/e...Documents.aspx I have not found information yet as to what temperature the brass itself needs to get to, but I suspect it depends largely on the alloy you're using.
All of this is to say that I don't know if I can get by with a small hand held style butane torch or not. The cost of these units is fairly cheap, but I imagine the refills of the gas is where the hidden costs lie. I plan to do some tests before ever putting anything out on display of course, but I'd sure appreciate if someone could shed some light on the subject for me. Can you use butane? Can you buy a narrow flame benzomatic mapp gas torch kit?
Thanks in advance! Happy mounting!