Taking Neon I at the Crucible

I took the Neon I intensive week-long evening class at the Crucible in Oakland, with teachers Dan Kuppe and Kat. I learned to make a neon sign! It's still awaiting final infusion of gas, but I'll share photos here once it's finished.

Here's much of what I learned, at least the parts that can be translated into text.

At the Neon 1 level, the craft is almost entirely around making shapes out of glass. The starting point is lengths of glass tubes - I think ours were 10mm in diameter and 4 feet long.

The way you make those shapes is by heating up and bending that glass, using a variety of gas torches.

This can be done mostly by naked hand - protective gloves weren’t necessary for the bends that we made.

You hold the glass over the gas flame and rotate it constantly to ensure it is equally warmed. Then after som time - usually 15-30s - the glass becomes malleable enough that you can bend it.

The key trick to getting the right bend is heating the right section of the glass. For a tight corner you heat just the very short segment that will form the corner. For a long curve you heat the section that will be part of the curve.

Bending the glass upwards is more effective than bending it downwards - you can use gravity to help, especially useful for larger curves where the glass will naturally sag once it hits the right temperature.

For corners you need to ensure the glass both stays sealed but has a hole that the neon can flow through later. You can help achieve this by blowing air into the glass tube, using a stopper at one end and a rubber hose attached to a mouthpiece at the other.

In a Jedi-make-their-own-lightsabers move, we created our own mouthpieces for the hose by putting a 90 degree bend in a thin tube and then heating and flaring out the end using a torch and a file. I dropped one of these and had to make another one.

It is crucial you don’t blow into the glass while it is in the flame because it is likely to burst! Instead you blow when the glass has just come out of the flame but is still hot - this can visibly affect the shape of the bend you are making. The goal is to have as close to a round hole in the center of the pipe as possible, although even a misinformed oval will still be OK as long as air (and eventually neon) can flow through it.

The best way to achieve a specific shape is to draw it precisely on paper, then cover that paper with a wire mesh so you can drop the glass onto it while it’s still malleable and form it to match the illustration. If you forget the mesh (I did that once) your paper will catch fire!

A tricky skill is planning out the sequence of bends that you will perform on a piece of glass. I haven’t developed a good instinct for this yet. You need to consider the rotation of the glass on the burner - if you create the wrong corners too early you won’t be able to safely position it on the gas such that you can rotate it without burning your hand or getting the glass caught on the apparatus.

Cutting the glass is quite easy: score one edge with a file and then tap it firmly such that it breaks. Some of my breaks were clean and others were jagged, and I’m not sure why but people with better technique consistently achieved clean breaks.

By far the hardest technique (for me at least) was welding. This is when you have two glass tubes and you wish to join them together as if they are one - important for combining pieces of the right shape, fixing breaks and attaching the electrodes at the end (more on that below).

To weld you wedge one glass piece firmly on a table with weights such that the end you attach to protrudes over the edge. Then you align the other glass piece with it and use a hand-held torch to rotate around and heat the ends of the glass tubes - keeping them about half a centimeter away from each other.

Once they are hot enough you kiss them together, then continue to heat the junction to get it malleable. Then you remove the heat and blow down the tube while stretching it out a little to try to get a clean merged section - ideally looking as close to a regular tube of glass as possible.

Doing this requires depth perception and a lot of practice. I only have one working eye, which usually doesn’t affect me much but turns out to make welding incredibly hard do to the need to align two glass tubes and a hand torch all at the same time.

The final step is to attach electrodes to the ends of your glass segments. These come as short glass tubes with wires coming out of them, which you weld onto the ends.

One of those electrodes will have a thin glass tube protruding from the end. This is used later on to insert the neon (or argon) gas as the final part of the process.

A few more miscellaneous tips I picked up:

• The final piece should not have two glass tubes touching each other as this can cause arcs to interfere with each other. A thin layer of silicon between the tubes fixes this.
• Neon comes out orange, argon comes out purple. There are colored glasses that can achieve other colors but we didn’t use these in our beginners’ class.
• It’s important to wrap your rubber hose around your arm in a way that avoids it coming into contact with the burner or hot glass.
• Use wooden paddles to help flatten glass shapes while they are still warm. Using cold metal can cause the glass to weaken or fracture.

Created 2026-01-11T09:34:29-08:00 · Edit