Interesting properties of glass used for bulbs?

OK, not sure if anyone's seen this before or not, but I sure haven't.

Last night, I woke for some totally inexplicable reason, got up, wandered around for a while and went back to bed, using the following flashlight as the light source (no idea of the manufacturer, runs a 4.5V 750mA Krypton PR base bulb from a 4R25 battery), all I know about it, is that it's waterproof, and has (in my view) a decent beam and throw.




After I'd put the flashlight down again, and my night vision had returned, I noticed a light from where the flashlight was, at first I thought it was just something reflecting off the reflector, but there wasn't anything to reflect.
Upon closer examination, I doscivered that the glass of the bulb itself appeared to be glowing. The effect only appears to last for a few minutes after the flashlight is switched off, but with eyes adjusted to the dark, appears to be quite noticable, my camera's not sensitive enough to detect it though.

I'm just curious to know whether this is a common thing, and thought it was a curious little bit of information that someone might be interested in.

It's most likely coming from the material the filament is embedded in. Take a 2nd look at that.

A quartz-halogen lamp in a spotlight I have exhibits a very noticeable blue-white glow from the glass after it`s been shut off, that lasts a minute or so. I believe it`s a property of the quartz used - a variation that blocks UV emmissions from the bulb. I`ve noticed it in a few halogen lamps - even mains operated ones. Not all, mind - but it does seem to exhibit in all the types I have that claim UV blocking properties, for use in open fixtures.

The bulb in my 9Z`s old P90 lamp did it too - not so noticeable but if you covered the face while your eyes were dark-adapted, lit it for a few seconds then shut it off and uncovered it, you`d see a blue/grey afterglow from the glass bulb!

Yep, that's what I was doing when I was investigating, was more visible I guess because that thing's got a pretty large reflector (Hmm, 1W LS SE would look good in there...no...must control oneself...), Guess it *could* be a halogen bulb, I'm guessing krypton because it appears to be identical to a light available in a local shop, which is identical save for the body colour (also identical to a light on Screwfix as far as I can see (http://www.screwfix.com/app/sfd/cat/pro.jsp?ts=32446&id=18518), might have to get one for comparison...).

My Brinkmann Q-Beam Max Million does the same thing. The glass glows blue for a minute or so after I turn it off.

Is that a Nixie clock in the above picture, or a picture of a Nixie clock? I'm going to build one of those someday.

A friend of mine lives in a building that uses nice big ones in all the elevator displays and I keep thinking I need to make friends with the maintenance folks and see if they have any spares they will sell me

Hey I just noticed that! A Nixie clock is something I`d like to build too - I have some spare tubes here too that I traded for, and have been waiting for a way to use them. Did have a preliminary design for a wall mounted volts/amps monitor so I could see how much power everything in here took, but I recently discovered it wouldn`t work. I`ve already got a couple Nixie tube bench voltmeters so a clock would compliment those nicely. I know of a proven working design for a clock - see this site for more details. The guy`s got am impressive collection of vintage electrical glassware too - Nixies included.

http://electricstuff.co.uk/

Nixie Elevator Displays? Nice! We don`t/didn`t have anything like that in this country - at least not that I`ve seen. Nixies are rare as anything in these parts! Those large tubes can fetch a lot of money too so good luck getting hold of any!

I plan to build one - once I can find the Nixies for a sensible price...which seems to be darn near impossible.

There's about 100 of them in old unused, mostly broken equipment in our old school, tubes are perfect though. They just *will* not accept the fact that the things are never going to get fixed, or get used again, so the parts which could be useful to a huge number of folks sit there, gathering yet more dust.

The pic's taken from here:

<http://www.cathodecorner.com> if I remember correctly. Nice kit, but prohibitively expensive for the likes of me. I just have to hope that there's someone around my area who's got something with a heap of Nixies and and thinks it's junk...a strategy which has worked before. The things you're most likely see on the walls of my room are pictures of the likes of that clock, a big star chart, HEAPS of Dragon pictures/posters, a couple of license plates I found years ago, every other available surface is basically covered in computers.

Zelandeth -- I have a feeling that Aberdeen works much as schools in the U.S. (In fact, I got a degree from the College of Wooster, which has an exchange program with your school), plus I worked for many years at a certain well-known technical institute here in the Boston area.

If you want to get your hands on that stuff, don't ask the professors or the administrators yourself. Nope. Go ask someone who actually takes care of the labs. "Technical Instructor", "Lab Technician", or some similar title. They can almost always take care of getting the stuff de-allocated for you, and will be extremely grateful for it because it means that they can get the darned stuff cleared out of their storage rooms and they won't be getting asked to fix it in the future. Really. You'll probably get it for free, but if there's any question of value then let the technician negotiate with the administration for you. ("Hey, there's this guy who's willing to help us get rid of some of this old junk" sounds much better to an administrator than a student going to a professor who once used the stuff back in the '50s and has some nostalgic attachment to it and the fundraising it took to acquire it.)

Just a thought. I hope it helps.

Try to get anything out of a school - it`s impossible! Old kidney-bean-scale meters that were covered in dust in the back of a cupboard. Unsuitable for classroom use, unused for decades - would they let me rescue them? No! Would they let me buy them? No! Would they even accept a trade for some brand new, perfectly classroom-usable desktop meters? No! Do I understand why? No!

Schools are wierd. As wierd as this glowy thing from glass bulbs that begain this topic:



Trying to show the afterglow present following a minute or so of burn of this 2Mcp spotlight. It is more noticeable in reality, and the colour is a cold icy whitish blue.

hi,

My E2E also glows for about 10 seconds. (lamp base).

And you will notice any white LS also glows for a few minutes after use.

Abe.

Yep, the LED in the Mini-Cybalite glows for a while too, the phosphor itself I assume, as with flourescent lamps, (Dulux mini sufficiently for it to be easily located in a dark room for a goot 15-20 mins).

Well, I did manage to get a couple of Archimedes A3000's and monitors, but that was only by liberating them from the skip as they were getting put into it...which nobody complained about because they had been in the skip - for about 2 seconds (and some idiot chucked a perfectly good 15" multisynch monitor in as well...GAH!).

The LEd's in my Streamlight 3N also glow for a few moments after you shut them off. But none of the other 5mm white LED's I've got around here do that.

It's not enough to find it or anything like that, but if you turn it off with your eyes closed you can see it quite clearly.