UV light for kids room?

[dmc]

Decorating my sons (2.5 yr old) room and suddenly had a thought...

He love glow-in-the-dark things. Ceiling is covered in sharks and cows (don't ask) that glow in the dark for a while when they have been exposed to bright light for a while. You know the type - they are plastic and a sortof yellow-green colour.

Anyway...

When you see these things for sale in shops they are often glowing brightly under some sort of UV (AFAIK) light. Now all I remember from my electronics/physics days is that UV light is not good and that eprom erasers shouldn't be looked at. This is obviously different to the UV that I see in shop displays (UVA and UVB rings bells...).

What I would like to do would be to get a normal cheapo uplighter. stick it to the wall and stick a UV bulb into it. Something like KJ64U from maplin.co.uk for example.

Will this work? If so is it a sensible idea or are there bad things likely to happen with this much UV exposure (i'm guessing that this is nothing compared to the suns output).

If it won't work then can anyone suggest something that would? I know the shop displays use some sort of flourescent tube but ideally I would like to be able to dim this light using a normal dimmer switch (I assume there would be no problems with this?). I'm looking at flooding the ceiling really although if I could just light the room in UV with no side effects then even better!

Anyone else done something similar?

Cheers,

Darren

[Colin Wilson]

There`s a site somewhere (linked from an advert on

IIRC but I can`t see the advert there atm) where you can buy some sort of flourescent paint which is practically invisible under normal light, but looks great under UV ;-)

Failing that, there`s always something like...

[Steve]

`

I bet you could kick the response you need with the UV leds from Nichia

- the room will be dark enough that the leds will have more than enough power.

Steve

[The Natural Philosopher]

First of all, do make sure your black light can't be looked at straight. It will lead to conjunctivitis with prolonged exposure.

Fluorescent paints are available. I suggest you google on 'black light'; and Disco effects' and so on, because thats where we used to use it.

Dayglo paints sometimes are UV reactive. Craft shops stock em.

[Dave Liquorice]

Just had a quick play with low powered(?) UV source and No.1 Daughters bedroom (she is away...) which has a few glow-in-the-dark stars an moons. The UV source was a battery powered security type (came with a couple of UV flourescent marker pens).

The things that really kicked off contained optical brighteners (white photcopier paper etc). The glow in the dark things didn't show from a distance but the UV lamp when bought close really charged them up well.

As to the amount of UV coming from this lamp I haven't a clue. Nor about any problems of long term exposure.

[The Natural Philosopher]

Thats because they work by absorbing light in the visible spectrum and re-emittining it later. I have a T-shirt like this.

That's not fluorescence, its summat else.

True fluorescence is from phosphors and other strange chemicals. They aborb UV and re-emit visible. Paint loaded with that glows under UV.

I wish you took my advice to google

What you want is here

here here

so on ad nauseam

Just google on black light fluorescent paint.

[Andy Dingley]

Fluorescence is immediate, phosphoresence has a time delay.

From physics, either of them can work from absorbing any wavelength to emitting any wavelength, except that the wavelength must get longer. From chemistry, to find something that emits visible light needs something that absorbs at the UV or at least blue end of the spectrum.

Almost all of the cheap stuff is zinc sulphide, which gives that "halloween green" colour. It's a lousy phosphor, but it's cheap.

-- Die Gotterspammerung - Junkmail of the Gods

[Owain]

"dmc" wrote | Decorating my sons (2.5 yr old) room and suddenly had a thought... | He love glow-in-the-dark things. Ceiling is covered in sharks and | cows (don't ask) that glow in the dark for a while when they have | been exposed to bright light for a while. You know the type - they | are plastic and a sortof yellow-green colour.

That's luminous. They fade gently over a period of time and are supposed to be restful and reassuring. I had glow-stars except I had to wait until I was old enought to stick them to the ceiling myself :-(

| When you see these things for sale in shops they are often glowing | brightly under some sort of UV (AFAIK) light.

Those are fluorescent. UV light will cause anything that is washed with optical brighteners to fluoresce, including the bedcovers, pyjamas, etc. I think this effect might be rather more appropriate in a discotheque than a small child's bedroom :-)

Owain

[N. Thornton]

Hi

Firstly Ultraviolet light does damage eyesight. It can cause blindness if misused, and it it very easy to misuse it without reailsing what one is doing. Real uv is not something I would be putting in a kids bedroom.

Pointing the thing upwards is obviously not going to work, as kids are inquisitive, and he/she will climb up and peer into it, eyes wide open in the dark, and all of 6" from the light.

Some types of UV source are real nasty, some are much less so. In short this plan is not a good one.

What is less well known is that flourescent and phosphorescent things do not require UV to glow, all they need is a light with a higher frequency colour than they emit. So something that glows yellow or green would work well with blue light. Blue ilght, unlike uv, is safe. It is thus the obvious choice.

Blue filament bulbs are very inefficient, blue fluorescent tubes are much better.

Regards, NT

[Dave Liquorice]

Erm there is naff all visible light from this UV security illuminator. Plenty of UV and that is absorbed and re-emitted in the visible range. B-)

No need I'm not the OP. I just did a bit of research about UV and the glow in the dark things, they don't glow as he would like them to.

[dmc]

Thats the ones.

Maybe - but I am talking about the same bits of plastic. Several local shops sell these luminous stars etc - they have them on a stand with what I assume is a UV fluorescent tube over the top. There is some fluorescent paint on the stand but the stars themselves certainly appear to glow. I guess they are luminous and fluorescent.

From school discos many moons back I seem to remeber that dandruff can glow quite well as well :-)

Darren

[dmc]

Fair enough. I take it that disco lights and the things on glow-in-the-dark displays in shops are UV but rely on the fact that people are not looking at them for hours on end (although I wonder how shop workers stand on this...). Or maybe they are not UV after all - they certainly looklike it and they give out very little visable light.

Is something that is used in disco lighting likely to be ok or are these things just "less bad"? I noticed that one of the Safeway stores in Canterbury now uses UV lighting in the loos (and this is not to make things glow :-) - again, I guess it isn't somewhere you would be hanging around for long.

Interesting. Maybe I will take a look at the lights that are meant to be fitted in PCs - nice and small and reasonably cheap.

Hmmm..

Darren

[John]

A bit off topic - but why do I find that Blue LEDs (washer jets on the kids Corsa's) are difficult to focus on? (Red to a lesser degree)

[The Natural Philosopher]

There is a difference?

[ignored]

In message , John writes

[Suz]

And your white underwear under black clothes.

[Huge]

Have you considered making stuff out of electroluminscent sheet?

[Dave Liquorice]

Blue light refracts or bends more than red light when passing through different density substances. This means the cornea and lens in your eye bends the blue light to much causing it to be out of focus on the retina.

Age and hardening of the lens may make this worse I guess.

[N. Thornton]

Disco blacklights are lowest frequency uv plus visible violet, and are low power, the light source is spread out along the length of a low power tube, and there are warnings to mount them so they arent seen directly, to use them for limited times, and to use them with other lighting on. These warnings are not necessarily all heeded of course.

At the other end of the scale there are uv sources that are short wavelength, intense, and accompanied by no visible light. Sources ilke this can cause immediate blindness. I've worked with 1.6kW uv sources, and before I was there, there was someone who caught a glimpse of the arc and was [temporarily] blinded instantly. He got to see again later that day. Believe me, uv sources like that hurt!

The problem with using a blacklight in a kids room is that the kid is not going to take any notice of the safety issues, and will probably stick their nose on it sooner or later, with dark-accustomed eyes. The result can be swelling and inflammation of the back of the eye, temporary blindness, pain, and detachment of the retina from the eye. Its known as snow-blindness, and it is possible for it to cause permanent and considerable damage.

Far less bad than some sources. But, see above.

you cant see ultraviolet, its invisible. I dont know what they've got but it might well be violet rather than ultraviolet.

Regards, NT

[Fishter]

Apparently it prevents people being abel to see their veins..... i.e. they can't find somewhere to inject anything. Might be a bit extreme in a supermarket toilet, but I've not been to Canterbury!