COMBUSTIBLE GASES The heating of jewelry pieces during welding is done with torches, which mix oxygen or air with a gas. Hydrogen, natural gas, acetylene, propane and butane are the most commonly used fuel gases. The heating of jewelry pieces during soldering is carried out with torches, which mix oxygen or air with a gas. It is important to know the melting points and flux of the solder you use.
Make sure the fuel source is hot enough for the solder to flow. We use silver solder for almost everything we create in our employee study, so we have this handy chart available. But, if you use copper, gold, or another form of solder, you'll also need to know those melting and flux temperatures.