Frequently Asked Questions

2. What sizes and shapes of Luminglas are available?

If the shape can be drawn it probably can be made. Shapes like lightning bolts, letters, outlines of logos, have been made. The size limitation is only the size that is reasonable to handle and that can be fused in existing production furnaces. The larger the shape, the longer it takes to heat up and cool the glass. Shipping becomes very expensive beyond certain sizes, as does the tooling used to make large plates. Also, as plates get bigger they are harder to keep from warping at the 1400F temperatures inside the furnace. For really large areas, surfaces can be tiled together with smaller pieces. At the San Francisco Airport, the United terminal has a large wall made up of small square panels. The pieces can be cut to any shape that would fit together. The sandwiched sheets of glass are typically flat, but can be intentionally curved for desired effects. Shapes such as domes, curved panels, bowls, etc. can be made, let your creativity go wild (see photos in our Virtual Gallery).

Plasma Globes/tubes
1. Hows does a Plasma Globe work?
A plasma device, whether it is a tube or a globe, is a sealed glass piece that has what we call a "plasma" gas mixture inside. The term "plasma" is technically any ionized gas in a discharge tube (fluorescent lights, neon tubes, etc.) In this case it refers to a specific lighting effect. The gas mixture is primarily made up of inert gases such as neon, krypton, xenon, argon, helium, etc.  A "dopant gas" mix is mixed in in very small amount to form the thin filaments of light. The dopants gas also helps determine the color of the discharge. These dopants are carefully formulated, without them the globe (or tube) would just glow uniformly and have no filaments. The gas lights up with a high-voltage, high-frequency power supply that essentially broadcasts a field of energy causing the gases to light up, much like the Northern Lights. Nicholai Tesla worked with these devices and published an article describing how to make them as early as 1910. Since a high-voltage field exists around a plasma device, no conductive materials should be used to build the base. The power supply also needs to be located close to the globe. The wiring also needs to be kept away from any other conductive surface. No insulation is sufficient to insulate the wiring from a conductive surface.

Many people ask how long a plasma device will last. They do not just stop working. Over the years the fingers of light will get wider and less bright. This happens gradually. At any time the device can be repumped, depending on how the viewer feels about how the fingers look and how long it has been run (and also how much power is used to run it).

Crackle tubes
How do they work?
A crackle tube works similarly to a Luminglas device. The beads, coatings, the gases, and the power supply are the same. The shape is the only thing that is different. Virtually any blown glass shape can be made to light up as long as it can withstand being put under vacuum.  (This is an important safety concern: Never put a glass shape under vacuum unless you know what you're doing! Implosions can easily happen and are extremely dangerous!)  Large crackle tubes (2" or larger) are made with double walls. This cuts down the weight and forces the discharge near the outer glass wall. Double walled vessels of this type require careful designing to prevent the glass from cracking due to strains in the glass between the inside and outside walls.

Lightning tubes

What are lightning tubes & how do they work?

A lightning tube is similar to a large-diameter neon tube but the gas fill and power supply are different. The gas used is at a high pressure and the power supply often has been slightly modified to accentuate the movement. High-pressure gases are used because the higher the pressure, the thinner and brighter the resulting filament of light. The higher the pressure, however, the higher the voltage needed to run the tube and the higher the temperature of the filaments of light. Care must be taken to use high-temperature, thoroughly stress-relieved glass when building a lightning tube. The white lightning can be made to move slowly or very fast by adjusting the fill gas.