The colours of neon lights

What makes neon lights different colours?

As mentioned above, the actual glow colour of neon signs is determined by a combination of gases and other factors. Let’s take a closer look at both aspects to give you the full colour scope.

How neon light produces colour

The process of creating colourful neon signs begins with a glass neon light tube, which is typically bent into various shapes to form letters, logos, symbols, or other artworks and designs. Inside the tube, a small amount of neon gas is sealed, along with one or more other gases. The most commonly used gas for neon signs is argon, but other noble gases such as helium, krypton, or xenon can be used as well (but rarely are for different reasons).

So how do neon lights work exactly? When an electrical current is passed through the gas-filled tube, it excites the atoms of the neon and/or argon gases, causing them to release energy in the form of light. This process is called discharge. The specific colour produced depends on the combination of gases present and the energy levels of the excited atoms.

Factors affecting the colour of neon lights

Several factors influence the colour emitted by neon signs. Temperature and pressure play a role in determining the shade and intensity of the light produced. Additionally, the composition of gases used and the amount of electrical current passing through the tube contribute to colour variation.

But most importantly for the production of commercial neon signs, coatings applied to the inside of the glass tubing can also affect the colour by altering the wavelength of the emitted light. Next to our “Classic” neon colours, which use the natural colours of the gas mixture inside the tube, Sygns neon colours are divided into two additional categories: “Powdered” colours, which are produced by an internal coating of the glass tubes that appears white when the neon sign is turned off; and “Coloured” colours, for which the glass tubes are coated with the specific colour to be achieved, which means that the tubes stay the same colour when turned off and on.

By manipulating all these factors, manufacturers can create an extensive range of shades to suit different artistic and commercial needs.

How adding other gases can change the colour of neon lights

While neon gas itself emits a reddish-orange glow (our “Classic Red” neon colour), adding different gases can alter the colour spectrum. Argon, for instance, naturally produces a lavender hue or, in combination with a tiny amount of mercury inside the tube, a light blue discharge (also known as our “Classic Blue” colour).

Helium produces a bright orange or pink shade, while krypton generates a pale white or very pale blue colour, and xenon creates a cool blue tint. The noble gas radon technically has a hot red discharge, but can’t be used commercially due to its radioactivity. By combining various gases and adjusting their proportions, a diverse palette of neon light colours can naturally be achieved, but – as previously mentioned – the only commercially relevant noble gases for neon sign production are neon itself and argon. The other gases from the noble family are not typically used anymore for various reasons; the most important being high production cost and chemical properties that render them inefficient for commercial purposes.