Searching for True Neon

Neon lights were available at the turn of the 19th century and for maybe 50 years they were the dominate specialty display lights. About 1950, florescent lights became available.

Neon lights have neon gas at low pressure in a glass tube between two electrical poles. The current goes through the gas exciting the neon atoms to a higher energy state, when they fall back to the ground state they release of photon that is the characteristic red/orange color. Other noble gases( helium, argon, xenon, krypton, radon) can be used in such a fashion but the color they produce is an unappealing color( argon(pale lavender), helium(pink to orange) ) or the gas is too expensive( xenon(60X neon), krypton(400X neon), radon(4000X neon)).

In the 1950s fluorescent lights became available, they work on the same principal but in this case the tube is filled with argon and a small amount of mercury. The mercury is excited by the electrical current and radiates in the ultraviolet range which has no color to the human eye. But the inside of the fluorescent tube is coated with a "phosphor" which adsorbs the ultraviolet light from the mercury and reradiates the energy at a visible wavelength. By using different coatings of "phosphors" on the inside of fluorescent tube almost any color can be produced. With multiple coatings the color produced can be changed according to the voltage used to excite the mercury vapor. Only the red in the photo below could be true neon(which it is).

The use of "phosphor" coatings(some don't include phosphorus) is so flexible and useful that they are replacing the original neon lights that used only neon gas. So finding "neon lights" that actually use neon is a challenge. I'm up to it.

We're looking for the reddish/orange, everything else is florescence, but not all reddish/orange in neon. To find the true neon you have to see the tube when it is unlit. In this case the tube is colorless, if it uses phosphors then the unlit tube looks like any fluorescent tube with a coating of white powder on the inside.

In the photo below we have lots of colors but which one is neon?

 When the lights are off, we can see that only the violin has clear tubing, it's the true neon.

 Neon is the old technology so looking for old signs is where to go. Like this one, true neon.

With binoculars, I see the tubing is clear.

(Should get back to looking for a cure for cancer, but this is more fun.)


All these tubes are at pressures less than atmospheric pressure so when they break they implode(in), not explode(out). They have mercury(a poison) and "phosphor" powder inside. Let experts dispose safely.