Have you ever noticed a neon sign when it was turned off and realized that the glass wasn’t colored? While some neon lights retain their color when they are turned off, many look clear. So how do these lights get to be so bright and vibrantly colored if they consist of plain white or clear glass?
Manufacturers make a typical neon light by filling a sturdy glass tube with neon gas. When a spark lights inside this tube, it naturally emits a deep red color. Craftsmen make the other colors you see in neon signs and lights when they mix neon and another gas or fill the tube with another noble gas entirely. The amount of gas in the tube also factors into the exact color the light produces.
The gases used to make bright, multicolored neon signage commonly include mercury, argon, and helium. Below, we’ll walk you through the characteristics of several of the most common gases found in neon signs.
This gas is where the name for neon lights comes from. Neon actually exists in the air we breathe, but only in trace amounts. It’s easy and inexpensive for manufacturers to obtain pure neon, and they only need small levels to fill lighting tubes.
As previously mentioned, pure neon gives off a deep red glow at normal levels. If the tube contains higher levels of gas, you’ll start to get a paler red or pink. Pure-neon light represents an extremely efficient light source for signs.
Mercury vapor creates a soothing and gentle, blue glow. If you watch street lights when they first come on, you may catch a glimpse of the blue color from mercury vapor (as most of these lights rely on mercury for their chemical makeup).
Most neon signs have either neon or mercury vapor in them, depending on whether the manufacturer wants to create colors with a cool or warm base color. When a manufacturer wants cool colors, like green or purple, he or she likely uses mercury rather than neon.
Craftsman typically mix argon with mercury to produce a stronger, more vibrant blue color. Sometimes the manufacturer paints the inside of the glass tubing with ultraviolet-sensitive phosphors to create different colors. The mercury in the combination gives off ultraviolet light and makes the phosphors glow.
When you see a neon sign with clear, effervescent blue, green, yellow, or white coloration, the tube likely contains argon gas.
In colder areas, manufacturers can add helium to the mercury and argon mixture to make the light heat faster. Alone, helium creates a pinkish-red glow. Of the gases on this list, pure helium is one of the most difficult to procure. Most industrial-grade helium results from radioactive decay or comes from a natural gas deposit.
Xenon produces a deep lavender glow. Craftsmen use xenon primarily in strobe lights and photography, though they also add it to the mixture inside a neon light. When combined with other noble gases, xenon shines in a wide array of colors.
Krypton emits a low, whitish-yellow glow. Because of this characteristic, manufacturers use krypton to produce a large variety of colors. When craftsmen add krypton to lighting tubes, they typically rely on colored glass to produce the perceived color. Outside of neon signs, manufacturers also use krypton gas for safety lighting, including airport runway lighting.
Every neon light represents a complicated chemical reaction to produce beautifully vibrant colors. When you look at your neon signs and the signs of businesses around you, see if you can guess what gases create those glowing lights. Or, if you’d like to add new colors to your current neon signage, ask a professional which gases are readily available for you to use.