Neon light

A neon light is a light made of a glass tube that contains a mixture of neon and argon gas. Different gases are used to produce different colors. The gas discharge emits light when the electrons of an atom are excited. Crafting the actual sign is quite easy by heating the glass tubes and bending them. If the signs are broken, the only hazardous element is the mercury. There are policies that neon signs have to go through to make sure it is safe if they are broken. If such a thing happens, the area needs to be well ventilated because concentrated amounts of the neon, argon, or whatever gas has been used, is not good to inhale and can cause side effects that are harmful to the body.

Neon can last decades. A neon sign that is on twenty-four/seven can have a life span between eight to fifteen years. Neon was discovered in London around 1898 by Sir William Ramsay and Morris Travers. The neon light was discovered by Jean Picard around 1675, not knowing what it was. Neon signs were later developed around the 1900s by Georges Claude. Neon is not toxic and can be breathed only if it is not a concentrated amount and it is in an open space. However, if neon liquid touches the skin, it creates frostbite.

History

The first neon sign sold in the United States to a car dealership.

How Neon was discovered

In London, England in 1898, soon after their discovery of the element of krypton, Sir William Ramsay and Morris Travers discovered the element of neon. Both elements were discovered through work on liquefaction air. A little later they discovered the element of xenon using similar methods. Neon comes from the Greek word "neos" which means "the new gas". Neon is a rare gaseous element that is present in the atmosphere to the extent of one part in sixty-five thousand of air. It is obtained by liquefaction of air and separated from the other gases by fractional distillation.

Discovery Before Neon Light

In 1675, before electricity had been discovered, a man named Jean Picard discovered a faint glow of light in a mercury barometer tube. He was a French astronomer but like everyone else, did not understand what he had seen yet. What Picard saw was called barometric light which happened when the tube had been shaken. This discovery was not understood but was investigated by many. Once the principles of electricity was discovered, scientists were able to move forward with trying to create different kinds of lighting. Steps toward neon signs were made in 1855 when Heinrich Geissler, a German glassblower and physicist, created the geissler tube. The geissler tube was invented after electrical generators were invented. Many inventors began conducting experiments with geissler tubes, electric power, and various gases. If a geissler tube was placed under low pressure and an electrical voltage was applied, the gas would glow. After years of experiments, several different types of electric discharge lamps (vapor lamps) were invented in Europe and the United States by 1900. An electric discharge lamp is a lighting device consisting of a transparent container which had a gas inside that was energized by an applied voltage. This made the light glow.

Georges Claude

Georges Claude, a French engineer, chemist, and inventor, was born on September 24th, 1870 and died on May 23rd, 1960 when he was ninety years old. He created the electrical discharge in a sealed tube filled with neon gas in 1902 when he was thirty-two years old, and displayed the first neon lamp to the public on December 11th, 1910 in Paris when he was forty years old. On January 19th of 1915, George patented the neon lighting tube. George introduced neon gas signs to the United States and sold two of them to a Packard car dealership in Los Angeles. A man named Earle C. Anthony purchased the two signs that read "Packard" on them for twenty-four thousand dollars. After this, neon lighting became popular very quickly in outdoor advertising. They were visible in the night and daylight.

Properties

Neon is a chemical element with the symbol Ne and atomic number of ten. It is in the group noble gases on the periodic table. Also on the periodic table, neon is in group eighteen, period two, block p, and it's electron configuration is [He] 2s²2p⁶. It's atomic mass is 20.18 and it's atomic radius is 1.54. Neon's electron affinity is not stable and electronegativity is unknown. It's molar heat capacity is 20.786 J mol^-1. Neon comes from the Greek work νέον or neos, meaning new. It is a colorless and odorless inert (meaning not chemically reactive) gas. Neon has a density of 1442 kg m^-3 or 5 K. It is about two-thirds the density of air and is the second lightest noble gas after helium. It has no true chemical compound which means it forms no compounds to fix it to solids or join with other elements. At room temperature, neon is a gas. The melting point is around -415^oF or -258^oC. It's boiling point is about -410^oF or -246^oC.

Neon is the fifth most abundant chemical element in the universe after hydrogen, helium, oxygen, and carbon. However, it is a rare gas in Earth's atmosphere making up just 0.0018%, meaning there are eighteen parts per million of air. Because neon is quite rare in our atmosphere, both neon gas and liquid neon are relatively expensive, costing more than fifty-five times that of liquid helium and more than three times that of liquid hydrogen. Neon is a rare gas that is non-toxic. It is obtained by the liquefaction of air and separation from other elements by fractional distillation. In a vacuum discharge tube neon glows a reddish orange color and is therefore used in making neon advertising signs, which accounts for its largest use. It is also used to make high-voltage indicators, lightning arrestors, wave meter tubes and old-fashioned television tubes. Liquid neon is now commercially available and is used as a cryogenic refrigerant. Stable isotope forms of neon are produced within stars. Neon gas emits a bright red-orange color when charged with electricity. If a balloon is filled with neon, it will rise in the air but do so at a much slower rate than a balloon filled with helium will.

How Neon Lights Work

There are different gases and fluorescent coating in the tubes to make them different colors.

How Neon Lights Work

A neon sign is made of glass tubes containing a mixture of neon and argon gas. There are two electrodes, one positive and the other negative. Voltage rises and an arc is struck between. Argon gas is used in other fluorescents as well because of a lower striking temperature. After the argon strikes an arc, the neon gas is warmed and current is able to flow through the neon gas, ionizing more atoms as the current rises. A ballast is necessary to limit the current since resistance will continue to drop as current rises.

The atoms of inert gases, like helium, neon, or argon, never form stable molecules by chemically bonding with other atoms. Although, building a gas discharge tube, like a neon light, is pretty easy. This reveals that inertness is a relative matter. Someone just needs to apply a small electric voltage to the electrodes at the ends of the glass tubing that contains the inert gas and the light will then begin to glow. Neon is not inert in a discharge tube but is inert to chemical reactions. The voltage across a discharge tube will accelerate a free electron up to some maximum kinetic energy. The voltage must be large enough so that this energy is more than what is required to ionize the atom. An ionized atom has had an electron pulled out of an orbital to make it a free particle and the atom it leaves behind becomes a positively charged ion. The resulting plasma of charged ions and electrons carries the electric current between the tube's electrodes.

Gas discharges emit light when an electron of an atom is excited. When the electron is excited it has an orbital of higher energy. When it eases back down it it's original orbital, a particle of light (a photon) carries away the energy making the tube glow. A photon's energy (its wavelength or color) depends on the energy difference between orbitals. This series of photon energies, the emission lines to a spectroscope, is unique to a particular atom. In a neon sign, the mercury discharge tubes have a very different hue than the neon discharge tube does. The inert gas helium was actually discovered this way, and observations of sunlight revealed a series of photon energies that had never been seen before in discharges.

How to Make a Neon Sign

The hollow glass tubes needed to make a neon lamp come in four, five, and eight feet lengths. When the glass is heated by lit gas and forced air, the tubes can be shaped. Several compositions of glass are used depending on the country and supplier. What is called "soft" glass has compositions including lead glass, soda-lime glass, and barium glass. "Hard" glass in the borosilicate family is also used. Depending on the glass composition, the working range of glass is from sixteen thousand degrees Fahrenheit to over twenty-two hundred degrees Fahrenheit. The temperature of the air-gas flame depending on the fuel and ratio, is approximately three thousand degrees Fahrenheit using propane gas.

The tubes are partially cut with a file while cold and snapped apart while hot. The artisan then creates the angle and curve as to what he wants. When the tubing is finished, the tube must be processed. The procedure in which the tubing is processed is called "bombarding". The tube is partial evacuated of air and then is short circuited with a high voltage current until the tube reaches a temperature of five hundred and fifty degrees Fahrenheit. The tube is then evacuated again until it reaches a vacuum of three to ten torr. Either argon or neon is filled to a specific pressure which depends on the diameter of the tube and then sealed off. If argon is used then additional steps must be taken for the injection of mercury. Usually ten to forty ul depending on the tube length.

Neon gas produces the color red. The neon gas glows with it's red light even at atmospheric pressure. Today there are more than one hundred and fifty colors possible. Almost every color other than red is produced using argon, mercury, and phosphor. Neon produces the color red, mercury produces blue, Co2 produces white, as helium produces gold. The mercury spectrum is rich in ultraviolet light which excites a phosphor coating on the inside of the tube making to glow.

Different Colors

To have a neon sign that has multiple different colors, different gases besides neon are needed. Other gases commonly used are helium, xenon, and other noble gases. Today, most other are colors are created by using mercury vapor. Neon gas produces a red color, however, if wanting blue, green, or yellow, phosphor with argon and mercury gas is needed. The argon starts in the arc, it warms up, then the mercury gas ionizes, and then the UV light is emitted. The UV activates the colored phosphor. For pinkish white and white, helium gas needs to be in a clear tube or it would work with mercury vapor and white phosphor. Neon gas with yellow phosphor creates orange. Helium and a yellow phosphor would create yellow. Krypton and xenon are also used to make whitish green and bluish white colors. Today over one hundred colors are available in neon lighting. Neon signs have become iconic in America and many storefronts still use them to attract attention. However, advances in technology have slowed down the use of neon signs in the past decade. Because of that, many people today who own vintage signs are now making sure that they are kept in tip top shape since some can be worth a lot of money.

Hazards

Neon and argon by themselves are not dangerous. They are inert gases that can be found in the air people breath every day. Therefore, it can be inhaled and absorbed into the body. Although, if inhaled in excessive concentrations, it can result in dizziness, nausea, vomiting, loss of consciousness, and even death. At low oxygen concentrations, unconsciousness and death may occur in seconds without warning. If pure neon was not contained, neon liquid evaporates very quickly which causes supersaturation of the air causing a serious risk of suffocation if in confined areas. If someone touches neon liquid, it causes frostbite, even on the eyes. Neon is a rare atmospheric gas and as such is non-toxic and chemically inert. Neon poses no threat to the environment, and can have no impact at all because it's chemically unreactive and forms no compounds. There are no known ecological damages caused by this element.

Although neon gas is not poisonous or explosive, the small amount of mercury found in some neon lights is not dangerous as long as the tube is not damaged. Some neon sign shops will not repair neon lights when mercury has been used in the manufacturing process. There can be a shock and/or fire hazard if the neon sign has not been properly insulated, wired, or mounted. However, UL2161 is an instituted policy that requires all neon sign power supplies to use safety features such as ground fault interruption and over voltage protection. These safety features protect the public from any shock or fire hazard. It takes anywhere from two thousand or fifteen thousand volts to power a neon light. Neon gas is not toxic at normal temperature and pressure. However, like other inert gases such as nitrogen and argon, neon is a simple asphyxiant. Simple asphyxiants can displace oxygen in the air, especially in a confined space. The lack of oxygen then causes the victim to suffocate. Proper ventilation is required.

Video

This tells of the history of neon signs, how it came about, and how they became an American icon.