Neon signs are made the same way since the invention of neon lighting in 1903. Each sign takes about 2 man days to make and each neon sign is made up of between 5 and 12 hand blown neon tubes.
All neon tubes start out as 4 foot straight raw tubes of glass. Some tubes have colored glass. When they are turned off, they appear similar to colorful stained glass murals in a church. The stained glass colored tubes are very expensive and are hand drawn even to make the raw tubes.
The other primary type of tube is white when turned off. These tubes have a phosphorus coating inside which turns argon gas to yellow, green, purple, white etc. Electricity excites the gas which then lights the phosphorus coating. The phosphorous coatings have different formulations generating different colors, so with handmade welds, a single tube can have many colors when lit. For example, multi-colored neon sculptures are all one single tube, yet they may consist of different phosphorus sticks welded together and then bent over a long torch by hand. Every single tube is welded and then bent by hand over a ribbon burner. Once the tubes are hand bent to the desired shape, the tubes are filled with either an argon/mercury mix or pure neon gas.
For the last step, electrodes are welded on the ends of the tubes and the raw bulbs are prepared to be filled with a noble gas by being cleaned with heat and electricity (30,000 volts). This is called bombardment. They are then attached to a vacuum pump, where all the air is sucked out of the tubes. When they are completely evacuated, the rare noble gasses are added and the tube is sealed. They are then "burned in" for 24 hours on a 12,000-volt transformer. They are then arranged, connected and mounted onto a metal grid. Finally, black paint is applied to finalize the artistic appearance of the sign.
Neon signs are delicate works of art that have many separate tubes daisy chained together. When one bulb is broken or goes out, the whole sign stops working. This is because the electric current runs in a closed loop. Neon signs, by definition, are gas generating lamps. That is, there is no filament and the gas itself conducts the electricity and gives off the warm moving light. Sometimes neon wavers because it is the gas that is carrying the electricity and gas moves. Heavy wavering normally goes away in 2-3 weeks.
If left alone on a wall and used intermittently they can last 20-30 even 50 years with no recharge. If left on 24/7 their life expectancy is 40,000 hours or 4 years. They are best when left alone, that is why it was the lighting of choice in Vegas for over 75 years. They operate best above 50 degrees Fahrenheit but can be stored down to -60 degrees Fahrenheit.