What UV Lamp Should I Get?

336nm or 224nm?

I want to be able to detect tagged stamps as well as florescent
Linder has one for 29 and 59 dollars..
the 59 dollar one does florescence and phosphorescence.

It depends on what country you want to ID tagging.

For US, you need the 224nm to see luminescent tagging.

The 336nm is useful for detecting fluorescent paper varieties, repairs, and paper faults.

For some countries, such as GB, the tagging barely or doesn't luminesce in the visible range for either wavelengths.

k

what does a normal black light..the kind you buy at a store put out? anyone know?

just make sure you dont go blind. there is one that makes you go blind it should be written ont he box as a warning. I always forget shortwave or longwave

uncle K,

please refresh our memory

Raytech has a dual wavelength UV light in their "Versalume" line, small enough to be operated as a portable light using AA batteries, but it also includes a power adapter so you can plug it into the wall when working at home. I haven't used this particular model so I can't offer any opinions on it, but I do have one of their high-end horrible expensive dual-wave lamps, and I'm happy enough with it that I have bought a second used lamp as a spare in case of problems with the original - probably an over-reaction, I've owned the first lamp for over 20 years now and it hasn't given me any grief.

http://www.raytech-ind.com/ultraviolet.htm

Raytech is popular among the mineral collectors and lapidary guys, and there are occasionally ebay listings for their lamps. I see it's being offered for US $80 right now.

Raytech also sells glasses to shield you from the harmful shortwave light. I have some Uvex UV glasses, they're just like safety glasses you would use in a wood working shop. If you're going to make it a habit to check every US stamp you get for tagging errors (I love finding tagging errors!), they'd probably be a good idea.

Ryan

one of these days we must get an image from you ryan of the stamps under the light

but yes virgin his advice is good but I would not check every stamp even with the glasses on. better safe then sorry especially with eyes

Hmmm, I cannot seem to find a couple of my posts of the past 2 days. But I didn't check to see if it posted properly after I submitted them. Anyway...

ALL UV is dangerous to cells with prolonged exposure. The eyes (retina cells) are particularly sensitive and the damage is usually irreversible.

In general, the shorter the wavelength, the more dangerous the UV (i.e., 200nm is more dangerous than 300nm).

Most of the small battery operated UV lamps are very low power, so eye damage should not really be a problem unless you get mesmerized and enjoy staring directly into the lamp.

I strongly recommend getting a philatelic/collectible grade UV lamp instead of the consumer-grade "black" light. The black lights usually emit a broad UV spectrum, and are not filtered. The stamp paper may fluoresce nicely, but the tagging luminescence will usually be very faint and can be obscured by the paper fluorescence.

I am looking at Raytech 10-028 Versalume Philatelic with the UV protective goggles they sell as well.

If you are only planning on examining single stamps, that model should suffice for US and Canadian stamps. 4-6 watts is sufficient for most philatelic needs. If you plan on frequently examining larger items, such as full panes, you will probably want to get a larger model. However, the larger models usually are not battery-operated, so you lose some portability.

Unless you are going to spend an hour a day using the UV lamp, the goggles probably aren't necessary. Just make sure you aren't using the UV lamps near metallic or reflective surfaces. Always set the stamps down and bring the UV lamp to it. Do not use stamp tongs to hold the stamp under the UV (the tongs are metallic).

I've never used the goggles (I can't because I wear glasses), but then again, my glasses have an anti-UV coating. My UV lamp is also constructed so that I can never "see" the UV lamp unless I flip it upside-down. The key is good safety practices; I think that is better than the goggles at these low power levels.

Have fun looking at tagging!

What about my metallic disco pants?

What happens when metal reflects or absorbs the UV light? I had not known of this safety precaution before now.

Almost all materials will absorb UV because it's photon energy is sufficiently high enough to be larger than the energy bandgap of almost all materials, and yet it's wavelength is not small enough to simply pass through most materials (as with X-rays).

The problem with metals is primarily with a non-trivial surface/interface reflectance of the UV, and also some metals will absorb the UV and re-emit in the UV (i.e., elastic and inelastic photon scattering).

You will see a similar problem with absorption and inelastic photon scattering if you put a metal pan or aluminum foil in the microwave oven (not recommended, of course).

Casual dancing with your metallic disco pants under a black light is not really a problem. The black lights are usually so far away that the photon flux is greatly diminished. Still, it would be wise to wear your sunglasses, if not simply to look cool. Those black lights are much higher wattage than the philatelic grade UV lamps.

Of course, if your metallic disco pants start feeling unseasonably warm...

Again, the metal problem is very minor unless you plan on using the UV lamp an hour each day. The thing to remember is that people have a habit of bending over to take a closer look. That will put your eyes that much closer to any metal reflecting or re-emitting. Don't lose any sleep over it. But then again, don't do your tagging studies on a metal-top desk or file cabinet!

Thank you khj. I do need to read a bit on my physics it seems, especially with all this nanotechnology happening elsewhere. I did not know of the idea of elasticity of photon scattering.

I do understand the metal in the microwave idea. I did that once with a reheat on a burger and left it in it's metallic wrapper. Oops. Pretty fireworks.

Elastic photon scattering is a very small fraction of total photon scattering events. I only mentioned it for the sake of completeness.

As for me, I just like to watch my stamps glow. If I start glowing later on, that's a different issue.

k

My friend who suffered permanent eye damage from doing some research with UV lamps. He was not wearing protective goggles and had the samples in a metallic vacuum chamber. He was not in my lab, otherwise I would have told him immediately. When I found out what he was doing after he had already spent a few months tinkering, it was already too late. He went from perfect vision to noticeable vision loss in a matter of a couple of months. He was using a much higher wattage UV lamp, so I don't want to give anybody a heart attack.

However, if you plan on long-term UV studies of stamp tagging, take care that your eye is not exposed to the lamp at any angle, and avoid metallic/reflective surfaces. Observe those 2 basic rules, and you should be OK, even if you don't wear UV filtering goggles.

On the other hand, if a fly went it just as you closed it, and you reheated it for 1 minute, the fly would come out fine -- you would probably be the one feeling uncomfortable.

After 2 minutes, I'm thinking the fly might explode -- but that's not my area of research/interest.