There’s a lot that goes into the making of a neon sign. Neon signs are a type of sign built with glass tubes that are filled with a special type of gas and then bent into shapes like letters and words, logos or other interesting designs. Once an electrical charge is applied to the tube, the special gas inside glows brightly.
Despite the name, neon gas is not the only type of gas used in the signs. Other gases, like argon , and sometimes xenon, are also used. These gases, along with phosphor-based coatings in the glass, produce a wide variety of colors that all glow very brightly. Neon signs range the every-popular small, window-mounted open sign all the way to a huge fifty foot high structure on the roof of a building.
After their heyday in the 1950’s, neon signs started to fall out of favor because of their relatively high cost as compared to the newer plastic “lightbox signs” as well as the more recently popular LED signs. In the last ten years, however, neon is starting to become popular again. Perhaps as the baby boomer generation got older, they started to realize that the nostalgic effect of neon might have a greater advertising impact than a less expensive sign.
The Basic Components
In the early days of neon signs, neon gas was used almost exclusively in all neon signs. Today, it is mostly used to produce orange or red colors. For other colors, argon, or a blend of argon and neon gases, is used. As mentioned earlier in the article, other gases, such as Xenon or helium can also be added for specific colors or effects. Additionally, a drop of mercury if often in the tube with the gas, as the mercury interacts with the argon gas, producing a brighter light.
The glass tubes in a neon sign are made from lead-based type of glass that is very malleable, and easily formed into the bends and curves needed to product the sign. On each end of the tube is an assembly called an electrode that allows the electrical charge to come into direct contact with the gas inside the tube. The electrodes are made from a special type of iron, with a wide, shiny contact inside the tube, and a small wire that sticks outside of the tube.
In order to excite the gas to the point where it lights up, a very high voltage is required. This high voltage is produced by a transformer that takes 120 volt A/C from your wall and multiplies it to a much higher level…perhaps 6,000 to 20,000 volts, depending on the size and type of sign. The transformer is connected to the wires on the electrodes, creating a loop. If needed, several different pieces of neon tube can be connected in series, with the transformer connected to the electrodes of the first and last tubes in the loop.
Making the Sign
Making a neon sign is both an artistic, as well as a mechanic process. Most manufacturing is still done by hand. Artisans select the size and colors of tubes they want for the design, bend the glass into shape, attach the electrodes, go through the process to get the neon or argon inside the tube, and then a series of steps to finalize the glass tubes before putting them together to make a sign.
Selecting the Glass Tubes
While some neon shops start with tubes of glass that are already coated and prepped, some shops start from scratch. The artisan starts by selecting straight lengths of glass and cleaning them well, then he inserts them into a machine that coats the glass with either phosphors, colored tint, or both. The machine blows the liquid phosphor or tint into the tubes, with the fluid draining out of the opposite end. Once an even coat is achieved, the tubes are dried in an oven specially made for this purpose. In some cases, the artisan may want a pure red, orange, or blue color, which can be achieved without a coated tube. For those effects, the glass tube can be used in it’s initial state, without any coating at all.
Shaping the Glass Tubes
The tempate for the sign, created earlier, is laid out onto the work surface. While these templates used to be made of an asbestos weave, most shops have moved to safer type of heat resistant fabric. In addition to templates, many sign makers use various jigs to help them in making shapes, including some very simple jigs like glass jars or metal cans.
After heating the glass with gas-fired burners to make it soft, they bend the glass to match the template. Bending glass is a skill that can take years to master, as improper bending can cause the glass to break, collapse and seal up, or become too fragile to be used in a sign. There are special techniques they use for the various types of turns and corners, as well as for complex tasks, like creating scripted lettering.
Each finished piece of glass tubing that will go into the sign also needs two additional features before the next step. The shaped tube needs an electrode at each end, as well as a small tubular opening, commonly referred to as a tubulation, to allow for removing the air inside the tube and inserting the gas. The artisan heats the end of the glass tube while also heating the electrode at the same time, and then joins the two molten ends of each piece into a smooth, seamless joint.
After the shaped glass has it’s electrodes attached, and has cooled off it’s ready for bombardment. The bombardment process removes impurities from the inside of the tube and the exposed ends of the electrodes. The air inside of the glass tubes is removed with a vacuum pump, and then a small amount of air is let back inside. An extremely high level of voltage and current is then applied to the electrodes, which heats up the tube, removing any impurities that would make the sign less bright, or cause flickering.
Adding the Neon and/or Argon
Following bombardment, the glass tube is allowed to cool off in preparation for adding the gas. Since the gas itself is pure, and is being inserted into the newly purified tube, the artisan has ensured that the tube will glow brightly and have a long service lifetime. In some cases, a drop of mercury is put into the tube to create a more briliant light. Once the gas is at the right pressure level, the artisan uses a gas fired torch to heat and pinch the tubulation, sealing the gas inside. He then uses the torch to cut off any excess glass from the sealed end of the tubulation.
Burning in the Gas-Filled Tube
The glass tube is now ready for aging, or “burning in”. This process consists of applying a slightly higher level of electric current to the tube than it will use in it’s final form. A heavy duty neon transformer is attached to the electrodes, and a higher than normal amount of electricity is applied, and the tube is aged for a period that could range from a few minutes to a few hours, depending on the type and mixture of the fas inside. If a drop of mercury was used in the tube, the tube is rotated slowly to allow the mercury to create an even coat on the entire inside surface of the tube. During this aging process problems such as a flickering effect, low light levels, or an overly bright spot on the tube are watched for. If a problem is observed, they will try various techniques to resolve them, or potentially, they will remove the gas and start the process over again.
Assembling the Sign
After aging, the bent glass is ready to be installed on the sign. The sign tubing can be supported in several different ways. Small indoor signs can have a steel skeleton backing, or a molded acrylic backing that supports tubing, the transformer, and the switch or pullchain. The framework or backing is usually black so it will be less visible, creating the effect of words “floating in place”. In these small signs, small plastic standoffs clip the glass tubes, and are glued or screwed into the backing. Larger signs, like those used outdoors, may be supported by a steel or aluminum framework and clips. An outdoor sign will typically have it’s transformer mounted in a separate, weatherproof container.
In a day and age where everything is mass-manufactured, neon signs are a throwback to an earlier time when everything was hand crafted. The end effect evokes a nostalgic feel that can’t be recreated with a cheaper lightbox or LED-powered sign. And that feel can translate into a competitive advantage for a business. If everyone is looking at your sign, you’re certain to get more foot traffic and attention than your competitors. And, despite the relatively “old school” style of manufacturing, they do enjoy some modern improvements, like higher-efficiency power supplies that reduce their operating costs and eliminate the “hum” you might associate with a neon sign.