Cold-Cathode/Neon glass making course... in the USA too...

[Nick]

I'd been looking for a top one-to-one cold-cathode display making course and had asked everyone I could find who was the best person to go to - they all said that Richard Wheater was the man at Neon Workshops in Wakefield (UK) ... it's the only place... BTW, Richard was responsible for the nice new "PEOPLE LIKE NEON" banner on the group homepage...

So, last week I went up t'north and learnt more in the hours I was there that I had in the previous 15 years or so of playing with neon. Like most of us, I have an understanding of the physics involved, but there are only a few who have got to grips with the glasswork side. 

Whilst Richard is an artist and not primarily interested in neon signage, I have a specific project in mind that required me to understand how letters are made - thinking this would be relatively easy, I decided to try to make initial letters of our children - an "H", "W", & "R"...

What I learnt was that glass bending, especially with narrower tubes, is very tricky - I found it very tough, but extremely rewarding. Richard was sympathetic to my travails and helped me immensely - at the end, I was enlightened (literally) and now have an infinitely better understanding of what is involved in actually making tubes, as opposed to just wiring them up in subtly different ways.

For those of us in the USA, Richard is running a "hot glass studio" workshop at Lite Brite Neon in Brooklyn from April 17th to April 19th 2015 .

If any of you US-based folk want to do a 3-day, hands-on, cold-cathode fabrication course with a great instructor, this is for you... and its not just during the day... evening sessions involving Q&A sessions etc. with well known NYC neon artists and visits to neon-related exhibitions etc. are also included. - drop me a PM if you want to get more background or just if you are interested. Its great fun...

Cheers

Nick

[John Rehwinkel]

I'd been looking for a top one-to-one cold-cathode display making course

So, last week I went up t'north and learnt more in the hours I was there that I had in the previous 15 years or so of playing with neon. Like most of us, I have an understanding of the physics involved, but there are only a few who have got to grips with the glasswork side. 

What I learnt was that glass bending, especially with narrower tubes, is very tricky - I found it very tough, but extremely rewarding. Richard was sympathetic to my travails and helped me immensely - at the end, I was enlightened (literally) and now have an infinitely better understanding of what is involved in actually making tubes, as opposed to just wiring them up in subtly different ways.

For those of us in the USA, Richard is running a "hot glass studio" workshop at Lite Brite Neon in Brooklyn from April 17th to April 19th 2015 .

If any of you US-based folk want to do a 3-day, hands-on, cold-cathode fabrication course with a great instructor, this is for you... drop me a PM if you want to get more background or just if you are interested. Its great fun...

I too have taken a neon bending course (actually, several, at this point).  I agree that it's fun, satisfying, and most enlightening.  You can find basic courses cheaper than this one if you just want to get your feet wet, but this sounds like a world-class course and I expect it's worth the money.

- John

[gregebert]

Does cold-cathode production require bombarding ? I was going to get started in neon art about 10 years ago, but the dangers of bombarding outweighed the rewards in my opinion.

One little mistake, and you die. None of the few remaining neon shops in my area would accept bombarding jobs, so I never got started.

I frequently work on live nixie circuits up to 450V, which are current-limited for safety, and I've never been shocked. Kilovolts are entirely different matter, though.

[Instrument Resources of America]

Anyone want to try and explain bombarding to me??? What, why, where, when, how  etc.     Thanks, Ira.

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[gregebert]

Bombarding is one way to bake-out impurities in the glass, electrodes, phosphor, etc in a neon tube. Generally it's done using a current-limited high-voltage source, running at a much higher current (hundreds of milliamps, which is deadly) than normal operation (20-50mA, depending upon tube diameter). From what I recall, bombarding is started once the vacuum is around a few torr and the current is adjusted until the glass reaches a high temperature (around 500F I think), during which the electrodes will be almost red-hot. As the gas heats up, the pressure will increase and you continue pumping to remove the impurities as well as maintain bombarding current.

I recommend reading-up on Paschen's Law, which describes how the ionization voltage decreases with pressure until a minimum is reached, and then increases as pressure is lowered further.

As the pressure is lowered below 1 torr at high temperature, the impurities are released and drawn out thru the vacuum port. This is where things can get really scary, because I've heard of cases where flashover occurs and an arc will go thru the neon work, into your manifold (multiport section for managing your pump, fill-gas, vacuum gauge, etc), and thru the pump. Yikes. Most setups I've read about use a 2-stage mechanical pump for the primary pump-down, and a diffusion pump to get below 1 torr. You also need good vacuum gauges. You can easily spend over $2000 US on the equipment.

I also recommend reading about diffusion pumps; I never heard about them before researching neon work.

After some amount of time, the bombarding is stopped and the glasswork cools, the vacuum is continued and I think I've seen people going down to 50 microns. Then the fill gas is introduced and pressurized to get optimum glow. Some mixtures require mercury; I'm not sure how they introduce it into the tube. Finally, the tubulation (electrode with a glass connector) is tipped-off and the tube is run for several hours to make sure it's properly filled, etc.

It's really amazing how much work goes into a neon-sign tube.

There are several good books on neon; See "Neon Techniques" by Strattman.

"Neon Engineer's Notebook" (Fishman & Crook) is very good; I was able to get a personally signed copy

[Per Jensen]

On 23 Feb 2015, at 21:39, gregebert <greg...@hotmail.com> wrote:

<CUT>

It's really amazing how much work goes into a neon-sign tube.

Yep.

This video is worth a look, too: https://www.youtube.com/watch?v=XAQ-pktuOuU

// Per.

[John Rehwinkel]

>> Does cold-cathode production require bombarding ? I was going to get started in neon art about 10 years ago, but the dangers of bombarding outweighed the rewards in my opinion.
>> One little mistake, and you die. None of the few remaining neon shops in my area would accept bombarding jobs, so I never got started.
>

> Anyone want to try and explain bombarding to me??? What, why, where, when, how etc. Thanks, Ira.

While cold cathode production doesn't necessarily require bombarding, it is the usual approach. It's done for two reasons. One is to clean out impurities in the tube so you can get a clean fill gas (the heat of the process breaks down and/or evaporates contaminants, so the vacuum pump can remove them), the other is to "activate" the electrodes by converting the carbonates into oxides by breaking them down with heat. You can also clean your tubes by baking them in an oven while pumping, and activate your electrodes with induction heating with an external apparatus such as the Fluxeon.

The usual procedure is to hook the tube to the vacuum manifold, and attach a large, high voltage, high current transformer with a variable supply to the electrodes. Pump the tube down to a low vacuum, then turn on the bombarder transformer. The whole tube lights up as whatever gases in it are ionized, and rapidly starts getting hot. It's cool to watch, as the color changes and striations appear in the discharge as the pressure changes. The person running it modulates the bombarder current as needed to get the tube clean. Normally, some method of monitoring the tube temperature is used to determine when it's up to temperature.

Then the tube is pumped down more, and the bombarder transformer is switched on again and adjusted to about ten times the normal tube current. The lower pressure concentrates the heat in the electrodes, which warm up to glow red hot, at which temperature they become activated.

The classes I took, the students were allowed to watch bombarding from a safe distance if they wished (I always did), but weren't allowed to operate the bombarder themselves.

After a bunch of classes, where I demonstrated that I could work safely and take direction, and convincing the teacher that I understood the bombarding process and its dangers, I was eventually allowed
to bombard my own tubes with supervision. I made and bombarded many of my own tubes, and I'm quite proud of them.

That shop had since acquired an oven so they can clean tubes without bombarding them, and they may well have gotten an induction heater to activate electrodes as well. If I were going to set up my own shop, I'd go that route, as bombarder transformers are big, heavy, power hungry, expensive, hard to obtain, and DANGEROUS.

That said, I've loved gas discharges and high voltage ever since I was little, and I still enjoy watching tubes get bombarded.

- John

[Instrument Resources of America]

Thanks for the explanation. Much appreciated. Yep!!!   Working on all of the different types of instrumentation that I have over the last forty years, which included h.v. h.i. supplies, and also some fairly large hypot testers, makes one very careful, lest one becomes a speck of crispy crittered dust!!!   Ira.

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[Instrument Resources of America]

Many thanks John and others. It filled a void. I used to go to some neon
sign shops when I was a kid and beg for old sign transformers, up to 15
k.v. bring then home and proceed to make everything, from Jacobs
ladders, to spark transmitters (my neighbors just loved me), to Tesla
coils with them. Ira.

[Nick]

On Monday, 23 February 2015 20:39:17 UTC, gregebert wrote:

...stuff on bombarding...

In tube manufacture you can easily go down to 1 micron, or about 1/760,000th of an atmosphere - this is done with diffusion pumps - wonderous things that shouldn't really work, but do... 

You keep the pumps running whilst the tube is baked by the bombarding current - very scary - safety is absolutely key.

The gasses & other impurities driven off by the heat are pumped out, and then you backfull to between 5 & 30 Torr (about 1/25th of an atmosphere) with your favourite noble gas/combo, e.g. Ne, Ne+Ar, Ar+Hg, Helium, whatever.

There's a lot more still to do after that...

There are several good books on neon; See "Neon Techniques" by Strattman.

"Neon Engineer's Notebook" (Fishman & Crook) is very good; I was able to get a personally signed copy

The best for nixies is definitely Weston, but Grahame  Marsh leant me a copy of the 1935, "Neon Signs" by Miller & Fink - its still almost all accurate - the only things that have changed are some of the electrical safety & the use of asbestos etc

Nick

[Joe Croft]

We need a class like this in Chicago!! I would be there in a flash!! :)

-joe

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