Comments on: Shedding Light on Neon Signs

By: David Bradley

David Bradley — Thu, 04 Jun 2009 10:00:05 +0000

Strictly speaking, neon is the only gas that can be used for neon lights, but as discussed in the article the the other noble gases and mercury vapour are also available for use in fluorescent tubes.

By: colored light

colored light — Thu, 04 Jun 2009 08:05:42 +0000

other than these gases, are there any other that could be used for neon lights?

By: JohnA

JohnA — Fri, 09 Jan 2009 16:01:44 +0000

No, radon has never been used in the neon industry. I have heard a few scientific narrow-spectrum bulbs used small quantities to lower the starting voltage – but that’s it.

Pure neon, with nothing else, gives you the deep red color that is so familiar. It is in neon sign tubes at a pressure of around 15 mbar for this effect. In other words, mostly a vacuum with a small amount of pure neon added.

By: Thomas Webb

Thomas Webb — Fri, 09 Jan 2009 08:02:05 +0000

Question, was radon ever used in neon type lighting either by itself or as a mix with other gasses? I remember reading something about it years ago that it was mixed with neon to produce a very dark red colour. Thank you

By: David Bradley

David Bradley — Fri, 05 Dec 2008 17:44:09 +0000

Thanks for the additional information John, I think the Ne-Hg tube I saw mentioned was in a research lab forty years ago rather than being a practical device for illumination.

By: JohnA

JohnA — Fri, 05 Dec 2008 15:33:30 +0000

I’ve run a neon business for over 20 years. In my industry, I can’t imagine a scenario of using Hg in a neon tube. In fluorescent tubes (both cold cathode “neon” and hot cathode), small amounts of neon, krypton, etc. are added to the carrier gas to help boost output in cold temperatures. That might be what someone is talking about when mentioning neon-Hg. Visually, a neon-Hg tube looks just like an Argon-Hg tube, as the mercury discharge overpowers the discharge.

BTW, you can also make many colors now in a “neon type” tube without mercury by using pure Xenon gas. This works especially well for green, blue, turquoise, purple, etc. Adding Hg does boost the efficiency significantly however. For lots of light and low power requirements, Hg (unfortunately) hasn’t found a replacement.

By: David Bradley

David Bradley — Fri, 05 Dec 2008 07:36:44 +0000

JohnA, yes you’re right, but there are mercury-neon tubes as well just to confuse the issue.

By: JohnA

JohnA — Fri, 05 Dec 2008 01:29:03 +0000

No, neon tubes do not contain mercury. If you put Hg in one, it would turn it from bright red to blue. Phosphor coated tubes with Argon and mercury vapor sometimes get called “neon” tubes – though the proper term is now “cold cathode fluorescent”.

By: Ronald

Ronald — Thu, 04 Dec 2008 20:18:00 +0000

Bernd there are alternatives==>instead of Mercury they can us vaporized tungsten, but it is a bit expensive.

By: David Bradley

David Bradley — Thu, 04 Dec 2008 13:12:39 +0000

Bernd. I’ve corrected the point regarding Ne vs Hg. As to their being called inert. It’s not really a matter of opinion, they most definitely were called inert gases at one time, although they may also have had the noble tag too (that was certainly in deference to the noble metals), but even at school we had teachers who referred to them as the inert gases, and the older literature uses that phrases commonly.