Assuming you have referenece to your darkroom area, almost any light will do. A few minutes in normal room light won't hurt coated screens, as long as there is not a lot of sunlight. I use a yellow bug light just because it happens to be convient. God Bless.

 

Thank you very much. I will get it today.

 

I use a fluorescent shop light. No problems ..... Well, just that I can see better....

 

If using florescent lights and no cover with photopolymer emulsion you can start to expose your screen as it exposes much faster than dual cure. Both are not very sensitive until dry so coating screens is no problem.

 

By the I've heard the term "dual cure". What does that mean?

 

Screen Printing Garments: Understanding Direct Liquid Emulsions

 

A few minutes of light from a fluorescent lamp some 10 feet above should be no problem on a coated screen some 7 ft below as the low(18 or 40) wattage means that the fluorescent light losses most of its potent UV even just by travelling a few feet.

To boost confidence, try coating a 7" strip of emulsion on one side of a screen and leave it some 7 ft under a fluorescent lamp. Wipe an inch of emulsion off every hour to see how long it will take to expose your emulsion.

I turn off the CFL and turn on 3 yellow bulbs though just for some extra measure of safety

 

They make yellow covers and clear covers for florescent lights. My storage box is hung on wall and close enough to a few of my shop lights. Standard florescent bulbs put out very little UV light and with a standard light cover your ok. Daylight bulbs and color enhancing bulbs put out more UV light.

 

Most LED lights put out no UV. I tested this by putting a half covered(by cardboard) screen under a 100 watt equivalent LED bulb for 5 minutes. Exposed the screen with the cardboard covering the LED "exposed" section. After regular exposure, LED lighted side washed away clean.
Butch

 

Low wattage LED lights don't seem to throw their lights(or whatever UV they have) as far as fluorescent lamps even if you bundled them together to the same wattage or lumen as fluorescents.

For better comparison, a 100w fluorescent placed 6 inches away should expose diazo emulsion in about 5-6 minutes. Around 12-15 minutes if exposed 12 inches away. So at 5 minutes, a 100w household fluorescent on the ceiling probably some 72-84 inches away won't expose a screen coated with commonly used screen printing photo emulsion. Any similarly "exposed" image should likewise wash away clean.

 

Thank you guys for all the help...

What I did was I had a spare energy efficient bulb, painted that with yellow acrylic paint that I had. It's great!

By the way I have another question, I mixed the emulsion and it was all greenish color, then I exposed some of the emulsion (I pained some a piece of white paper just to test out), I exposed for 5 min under 500w halogen light.
The question is: Is it supposed to turn grey. Does the grey color indicate that 5 min exposing time is enough!!!?

 

I use a regular shop light and everything exposes just fine - no problems holding great detail, plus it's way easier to do my prepress.