The intensity of neon light produced increases as the tube diameter grows smaller, by the inverse square root of the interior diameter of the tubing, and the resistance of the tube increases as the tubing diameter decreases accordingly, because tube ionization is greatest at the center of the tube, and the ions migrate to and are recaptured and neutralized at the tube walls.
The greatest cause of neon tube failure is the gradual absorption of neon gas by high voltage ion implantation into the interior glass walls of the tubes which depletes the gas, and eventually causes the tube resistance to rise to a level that it can no longer light at the rated voltage, but this may take 7-10 years.
The actual cause of 80% of neon sign failures in strip malls on buildings conspicuous from the street has nothing to do with the tube life, but unbeknownst to the public is caused by the burnout of the high voltage electrical wires connecting the tubes inside of metal conduits, a traditional way of wiring neon that was formulated in a low voltage electrician's world.
A very common type of neon sign is made from a formed metal box having a colored translucent face, called "channel lettering." Newer channel letter signs are being replaced by high brightness LEDs.
Tubing in external diameters ranging from about 8-15 mm with a 1 mm wall thickness is most commonly used, although 6mm tubing is now commercially available in colored glass tubes. The tube is heated in sections using several types of burners that are selected according to the amount of glass to be heated for each bend.
These burners include ribbon, cannon, or crossfires, as well as a variety of torches that run on a simple combination of natural gas (butane or propane work better, however natural gas is cheapest) and air. Ribbon burners are strips of fire that make the gradual bends while crossfires, when used, make the sharp bends.
This long lifetime has created a practical market for neon use for interior architectural cove lighting in a wide variety of uses including homes, where the tube can be bent to any shape, fitted in a small space, and can do so without requiring tube replacement for a decade or more.
