nickfury

Hi,

I've tried to do a photogrpahic screen, and I got until the 'exposure' part. Im using a halogen flood light to expose my emulsion. But about 5 minutes later, my halogen light, started to smoke a bit. I got scared so I turned it off. Is this dangerous? The light wasnt really on fire, I think it's just heating too much.

 

Reply With Quote

wildpat

I have used halogen lights before and didn't have any smoke, but you could have had some oil or something from the factory burning off if it was new.

 

Reply With Quote

mckaymental

I use halogen light and I like it! I'm sure you'll find out some good things about it!

 

Reply With Quote

Screenanator

If your using a patio/outdoor light fixture dont forget to take the glass cover off...it's a UV filter....just use it open face ...but be careful....keep it 18-24 inches from your film.GOOD LUCK.

__________________
The Shirt Shak-TSS Grafx-TSS Sporting Goods...Gettin it done since 2001

 

Reply With Quote

nickfury

Yes, Im using an outdoor light fixture. If I keep it open, wont it make the bulb blow? I've heard that halogen bulbs are very sensitive, it could blow just by touching it with bare hands, before switching it on.

 

Reply With Quote

tpitman

You shouldn't touch the bulb with your bare fingers, something about the oil in your skin weakening the bulb. I know that bulbs on old vertical litho cameras were the same. If you have to handle it you should wear gloves or use a paper towel. The bulb isn't especially prone to blowing, though. I think the glass cover is to prevent overexposure to UV on anyone spending much time around it, and just to generally protect the bulb from anything hitting it.

 

Reply With Quote

RichardGreaves

Quote: Originally Posted by nickfury Is this dangerous? The light wasnt really on fire, I think it's just heating too much.

A halogen lamp is a fused quartz glass tube (that can withstand high temperatures), filled with a tungsten filament and halogen gas. The hot filament that emits light makes this an incandescent lamp not know as a good source of UV energy.

A side effect of using high temperature quartz is that it will not filter UV-A light emitted by the tungsten filament. Ordinary glass stops these rays. It is the invisible UV-B light that can cause eye damage and is not as good as UV-A for cross linking stencils.

The lamp has to get hot to get the tungsten filament to glow and the halogen gas counteracts action as the filament evaporates when giving off light and is chemically re-deposited at the hot spots.

Beware, some manufacturers add a coating of UV inhibitors on lamps destined for the home lighting market. When this is done, a halogen lamp with UV inhibitors will produce less UV than its standard incandescent counterpart.

Many household halogen lamps have an additional piece of safety glass to prevent fires, but they usually use ordinary glass, which, absorbs most of the UV-A light.

All that heat is infra-red energy. Quartz lamps emit more infrared energy than any other lamp. UV energy does not produce much heat, infrared energy does.

Sure. A halogen lamp is OK, but there are other lamps that are richer in UV-A radiation like metal-halide. SOME fluorescent lamps (Daylight Deluxe and BL Black Light) are very rich in UV-A, but they have very little penetration power so you have to keep them close to the stencil and pack them tight, to cover the stencil evenly with energy. A major benefit to fluorescent lamps it that they are cool to the touch.

__________________
How are you measuring? retired Ulano Technical Support
Screen printing since 1979 - SGIA Academy Member

 

Reply With Quote