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Discussion Starter #1
I built my own explosure unit, but I have been having trouble with explosing screens and I'm wondering if I'm using the right lights.
Where did I go wrong?

I built a 30*30 wood box, with a 32*34 sheet a glass to lay over the top.
I put 3-18''inch 15watt flouencent lights ( the ones that come in the fixture with the plug ready to be plugged in.)
I have tryied burning 3 screens, they all came out completely blank. I exposed them for 13min. they weren't under nor over explosed they were just completely blank.
Where could I have went wrong?
Also, while exposing I covered my design with coroplast to block light from going threw, and I put 4-100 pack dvd's on top of the coroplast to use as weights, and then covered it completely up.

Please Help Me. So that I can start printing.
What can I do? What could I have done wrong?
What are the best lights to use?

I wanted to get just the bulbs but I dont know how to hook it up to whatever it will need to make it plug into the wall.
If you have bulb #'s, part #'s, include those and I can find out if my local hardware store carry it.

Thanks, in advance:)
 

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they weren't under nor over explosed they were just completely blank.
I dont see how this is possible, what do you mean by blank?

you coated your screen with emulsion, exposed it and then what happened, did all the emulsion wash out? this would mean it is underexposed, did no emulsion wash out at all? this would mean it was overexposed. the problem has to be one or the other.
 

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I am going to say you overexposed. I have used a unit with 4 of those flourescent bulbs and the burn time was anywhere from 5-7 minutes (5 when the bulbs were new)
 

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Discussion Starter #6
I dont see how this is possible, what do you mean by blank?

you coated your screen with emulsion, exposed it and then what happened, did all the emulsion wash out? this would mean it is underexposed, did no emulsion wash out at all? this would mean it was overexposed. the problem has to be one or the other.
No emulsion washed out at all.
I checked it after being exposed for 5 mins. and there was no artwork exposed so thats why I left it for 13mins. I have F15T8 flourencent lights. 15 watt.
If it wasnt over nor under exposed, i'm guessing it was'nt exposed at all, but how could that be? What could I do to fix this? What could be the cause?
 

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TT, Emulsion is Ultra Violet light sensitive, 15 watt regular florescent put out very little. If you expose for about an hour you might get some results. You need black lights like they use in clubs to make white shirts glow. If you put the same screen in the full sun for about 15 min it will work
 

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Are you under the impression that you could just look at the screen and tell it is exposed without ever rinsing it out?
 

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Fuzz, I'm saying that a regular florescent bulb doesn't put out enough UV to expose the emulsion in a trimly manor, I don't think anyone can look at a screen and tell if its exposed. I was just trying to help as I've only been doing this for 20 years. If you have a better suggesting please advise us..
John
 

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Im sorry John, that was directed at the TS because he said,

"I checked it after being exposed for 5 mins. and there was no artwork exposed so thats why I left it for 13mins.".

I should have replied with his quote.
 

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two reasons it might have come out blank

A. You are using the wrong lights they need to be unfiltered black lights which you can find on grainger.com

B. the light was two powerful and it went through the positive film i usually print two positives and layer them on top of one another then expose.

but i honestly think its reason (A).
 

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The system I used for years (Universal 696 which i beleive is Morantz Screen-a-print now), was 4- 18" fluorescent bulbs (exact same as TS is reffering too) that were 12" from the glass. Exposure time was approx. 5 minutes with new bulbs.
 

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Just a couple of thoughts and a question...

1 - What happens when you try to wash the screen out? Does all the emulsion completely wash out or does the emulsion stay on the screen?

2 - Was the emulsion sensitized? (not trying to insult intelligence, but just asking)

3 - If the coroplast is white, it could be reflecting light back to the screen and overexposing.

4 - Is your artwork sandwiched between the glass and the screen with the lights below? You want the artwork to be between your light source and your screen.
 

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Discussion Starter #15
I built my own explosure unit, but I have been having trouble with explosing screens and I'm wondering if I'm using the right lights.
Where did I go wrong?

I built a 30*30 wood box, with a 32*34 sheet a glass to lay over the top.
I put 3-18''inch 15watt flouencent lights ( the ones that come in the fixture with the plug ready to be plugged in.)
I have tryied burning 3 screens, they all came out completely blank. I exposed them for 13min. they weren't under nor over explosed they were just completely blank.
Where could I have went wrong?
Also, while exposing I covered my design with coroplast to block light from going threw, and I put 4-100 pack dvd's on top of the coroplast to use as weights, and then covered it completely up.

Please Help Me. So that I can start printing.
What can I do? What could I have done wrong?
What are the best lights to use?

I wanted to get just the bulbs but I dont know how to hook it up to whatever it will need to make it plug into the wall.
If you have bulb #'s, part #'s, include those and I can find out if my local hardware store carry it.

Thanks, in advance:)

I figured what I was doing wrong. It was me the exposure units works great. I was over exposing the screens. Plus I found that if I rub the screen using my hand and water before I completely spray it out, the design comes right out.
 

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I hope it did not take you 2-1/2 years to find out. :D:D

But its really nice of you to update the thread. For reference, how high is the glass above the fluorescent? The F15T8 are regular fluorescent lamps right?


TT, Emulsion is Ultra Violet light sensitive, 15 watt regular florescent put out very little. If you expose for about an hour you might get some results. You need black lights like they use in clubs to make white shirts glow. If you put the same screen in the full sun for about 15 min it will work
Again, for reference. My very first exposures were done on a borrowed unit based on 20w regular household fluorescent tubes 12" beneath the glass. The unit has 4 tubes each switched on/off independently. For A4 sized images I'd turn on just 2 lamps. Usually, 12 minutes is enough but I sometimes lost track ot the time and the image still wash out good at 13-14 minutes. My artwork is printed on bond paper wiped with oil to make it transparent. Exposure times with acetates should be lower. Exposure times are based on the best results based on a step wedge test and not for durability.
 

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I hope it did not take you 2-1/2 years to find out. :D:D
ha,ha,ha... funny:)

I would have to add that I too have this set up, and I am in my 11th year of business and this is all that I have used for nearly 9 years now. I use the regular lights that come with the shop lights, and they are 6 inches from the glass. When the lights are new I am exposing at around 5 minutes, I am now exposing at around 6 1/2 to 7 minutes. I would also like to add the emulsion you use will play a role in your exposure times so I always recommend going with a fast exposing emulsion.
 
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