Neon, argon and the rest: what gas and glass make which color

Most of the colors in a "neon" sign don't come from neon at all. Neon gas makes the reds, oranges and some pinks. Nearly every other color you see comes from argon, a drop of mercury and the coating or color of the glass. Here's how a bender gets from a handful of gases to dozens of colors.

Neon: the reds, oranges and hot pinks

Pure neon gas in clear glass glows the classic warm red-orange that gave the whole trade its name. Put neon in coated or colored glass and you shift it: deeper reds, pinks and warm oranges.

Argon and mercury: everything else

Argon with a small amount of mercury glows a pale blue in clear glass, but the mercury's real job is making ultraviolet light. Inside a phosphor-coated tube that UV makes the coating glow, and the coating sets the color: whites, greens, blues, purples, golds and pinks. That's why most neon colors today are argon and mercury in coated glass.

One thing customers notice: argon and mercury tubes can look dim and patchy in cold weather, especially right after they're switched on, until the mercury warms up and turns back to vapor. In hard cold they may stay dim. Neon doesn't have that problem, which is why gas mixes with extra neon are used in cold climates.

The specialty gases

Benders also use a few rarer gases, often in mixes or coated tubes, for special effects. In clear glass they look like this:

• Helium: a soft peachy, orange-tinted white.
• Krypton: a pale silvery white, sometimes with a greenish cast.
• Xenon: a soft bluish white to blue-gray.

We carry all three in flasks alongside neon, argon and mixes.

Coated glass vs. colored glass

Coated glass is clear tubing with phosphor on the inside, so most coated tubing looks white when it's off and only shows its color when lit (some coated tubing has a tinted layer under the phosphor). Colored (tinted) glass is colored all the way through, so it shows its color even when the sign is off, and it filters the light from the gas inside. Some tubing is both colored and coated, and benders pick the gas and glass together to get just the shade they want.

Shop gas flasks, or call 480-820-9517 if you're matching an old sign's color.