Torches

Torch types

• Fuel + air – The flow of the fuel draws air into the torch, much like the familiar Bunsen burner.
• Fuel + compressed air – Mouth operated blowpipes, compressors or bellows can be used to force air into the torch to give a hotter flame.
• Fuel + oxygen – Pure oxygen from a tank is combined with the fuel to give the hottest flame.

Fuel types

• Butane – Not a traditional gas for jewellers, but is now commonly used at home. Refill canisters are also used for refillable cigarette lighters; this means that they are easy to buy at tobacconists.
• Propane – Another easy to obtain fuel, commonly used for gas barbecues.
• Acetylene – A very popular fuel with more experienced jewellers. Acetylene produces such an intense flame that it can burn a hole in most types of metal unless the torch is kept in constant motion.
• Natural gas – A gas tap from the mains gas supply will have to be installed by a qualified gas engineer. The gas itself is inexpensive, and you do not need a tank or a regulator. Not commonly used as a soldering fuel at home, but is common in both industry and educational institutions.
• Hydrogen – A micro-flame generator unit produces oxygen and hydrogen from water. The flame produced is very hot and focused, making it ideal for intricate work. The high cost of this equipment can be prohibitive for the amateur jeweller.

Flame types

• Reducing – A bushy, lively flame; deep blue in colour. This fuel-rich mixture is ideal for both annealing and soldering work.
• Neutral – The medium-blue flame comes to a sharp point with a gentle hiss.
• Oxidising – This thin, pale flame makes an angry hiss. There is insufficient fuel to be of any use when soldering.