The outside diameter of neon tubes is from 6 to 25 mm with a wall thickness of about 1 mm. The diameters of tubes in this range vary and depend on the manufacturer, but the following options are most common: 6, 8, 10, 12, 15, 18, 20, 22, 25 mm. Due to availability, ease of shaping and versatility of application, the following diameters are most commonly used: 8, 10, 12, 15, 18 mm.

A double back bend refers to a neon tube bend in which the tubing is bent back 180 degrees in relation to its direction to ensure the continuous line of the neon system. They are used for certain small letters/characters and connections between them. Thanks to double back bends, production costs and the voltage required to power the neon sign are minimized. The double back bends can be made in three planes (downwards, upwards, sideways) and usually this is consistent with the electrodes’ forming plane.

Since the electrodes are not covered with phosphor, they always light up in the colour of the gas that the neon system is filled with (Neon – Ne – orange-red or a mixture of Argon and Neon – Ar/Ne – pale blue). If the neon tube glows in a different colour than the gas inside it, electrodes that are not painted (with a special light-blocking paint) will have a negative effect on the appearance of the whole neon sign. Similarly, double back bends connecting individual letters/characters should be blacked out for better readability of the neon sign. Black paint, which best blocks the light of electrodes and double back bends, is most commonly used. White and grey paint is also used as standard. For large production runs, other colours can also be used. The colour of the paint should be chosen so that it blends as much as possible with the mounting base (wall, Dibond/Plexiglass backboard or metal frame).

There are two basic types of neon tubes: transparent (different kinds: sodium, lead, heat-resistant, etc.) and coloured (in a dozen or so colours, both transparent and matt). Both types of tubes are usually covered with phosphor on the inside (it is best visible in the case of transparent glass – these tubes are usually white when not glowing).

Electrodes are chosen according to the diameter of the neon tube and noble gas. Each type usually has diameters consistent with the diameter of the tube and two lengths (short and long). Electrodes are made of a several centimetres long metal core and a glass sleeve, which is connected to a neon tube. The sleeves of short electrodes are slightly longer than the core (that is why they cannot be shaped) and are only suitable for direct connection to the tube (straight shape – tube extension and perpendicular shape). The sleeves of long electrodes can be bent in many planes, which makes it possible to roll up the electrodes, i.e. to bend back the electrodes in relation to the neon tube. In addition to shaping the electrodes horizontally, the electrodes can also be bent vertically (upwards, downwards and sideways), thus obtaining the final combinations (perpendicularly upwards, perpendicularly downwards, bent back upwards, bent back downwards, etc.).

The ambient temperature affects neon tubes filled with a mixture of Argon and Neon – Ar/Ne gases (colours of light i.e. white, yellow, orange, pink, blue, turquoise, violet, green). At the limit temperature of approx. +7°C and less, such tubes may lose their luminous intensity or glow in a different colour. This effect occurs at random and is most often visible at the ends of the tubes and in the middle of the power-supply system. The lower the ambient temperature, the greater the loss of brightness of the neon sign. This problem is due to the loss of some of the chemical properties of Argon at that temperature and is not subject to warranty claims. When the ambient temperature returns to a level higher than +7°C (and remains at this level for at least a few days and nights) the tubes regain standard and uniform brightness.

The warranty covers all physical damage, which can be distinguished from mechanical damage, based on an inspection of the glass structure at the point of crack (in case of mechanical damage, edges of tubes are uneven) and based on an inspection of phosphor coating (if any) at the point of damage. If tubes are mechanically damaged, phosphor is separated from the tube walls at the point of damage due to rapid changes in pressure inside the tube. In physically damaged tubes (glass expansion), the pressure equalization process is longer and therefore their phosphor structure is intact at the crack point. Electrical damage is considered on a case-by-case basis and depends on whether the transformer/power supply unit was provided by the tube manufacturer and whether the electrical connections were made according to the enclosed diagram and instructions.

Dark spots may be present in neon tubes filled with a mixture of Argon and Neon (Ar/Ne) gases containing traces of mercury necessary for obtaining the appropriate brightness of illumination. When the tube is glowing (warmed up), mercury becomes volatile and can settle in random places, which may change over time. To eliminate dirt that has settled in a visible place, the tube should be heated up at this place (e.g. with a warm air blower) to move mercury to another place. Mercury spots are not covered by the manufacturer’s warranty.