# Screen Exposure Times using paper?



## dharmabrat (May 18, 2009)

Help!

I just bought a bunch of pre-exposed screens that are coated with Diazo DXP. 

When I learned screenprinting in college, we used photocopier paper for our images instead of vellum or transparency sheets all the time, and usually it took between 20-60 minutes for the screens to expose. 

Unfortunately, the instructions with these pre-coated screens do not include an exposure guide for people like me who are using paper.

Any suggestions? I live on an island, so getting my images printed on vellum or film is not an option. And I have 2 weeks before the screens "expire."


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## dharmabrat (May 18, 2009)

Oh yeah, I'm exposing with a 500 Watt Halogen.


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## Solmu (Aug 15, 2005)

Well, I think if we were being honest the most common advice you'd get is "Don't use paper."

If that just isn't an option (you can't get film delivered in time, you *have* to use paper), then my second suggestion would be to use a more powerful exposure source.

You don't want to risk underexposing the sections covered by blank paper by using a weak light.

Fortunately there are few places in this world without sunlight, so you have a free powerful exposure lamp at your disposal.

If you *must* use paper, my suggestion would be to use the sun to expose. The fact that your screens are pre-coated makes experimenting a lot harder unfortunately. I would have recommended that you coat a small section and test, but obviously that's not going to work.

If it was me, I guess I'd look up information on sun exposure, then double the exposure time for my first experiment. Exposure is not an area I'm great with though, so hopefully someone else will have some more enlightening advice


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## jmlampert23 (Nov 7, 2008)

you can get some films at staples if needed. also another thing to do if you are using paper is to coat the paper with a thin film of vegetable oil. i personally do not do this i do a lot of retail printing and whatnot but i tell people that are beginning and dont have all the tools to do that


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## dharmabrat (May 18, 2009)

Thanks for your honesty!

I wish that you weren't wrong about the sunshine...we've had a hell of a spring here in New England! Actually, today is a beautiful day! 

So, I have good news: I decided that I was going to have to sacrifice a screen in the name of scientific experimenting and my guesstimate worked perfectly.

I used one the the images I had planned on using that didn't take up the entire screen area, and exposed it for a full hour.

I used the rest of the screen to do a typical exposure test, with 10 minute intervals, from 30-70 minutes. Happily 60 minutes was the magic number and I got a perfect screen...although the washout took a little long, so I might move it to 55 minutes next time.

If we ever get a sunny weekend, I'd be tempted to use the solar rays, but now that I've got the exposure time down, I think I'll be sticking with the current system.


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## jmlampert23 (Nov 7, 2008)

what is your exact exposure time. i only expose for 30 seconds!!!!!


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## dharmabrat (May 18, 2009)

jmlampert23 said:


> what is your exact exposure time. i only expose for 30 seconds!!!!!


The suggested exposure time for a 500 Watt Hallogen, using vellum or film is 13 minutes. 

Clearly, this is a slow-exposing emulsion! So, for anyone else out there: 13 minutes for film = 55 minutes for paper!


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## jmlampert23 (Nov 7, 2008)

dharmabrat said:


> The suggested exposure time for a 500 Watt Hallogen, using vellum or film is 13 minutes.
> 
> Clearly, this is a slow-exposing emulsion! So, for anyone else out there: 13 minutes for film = 55 minutes for paper!


 
i expose vellum and waterproof transparencys. the vellum for 45 seconds and the transparencies for 30 seconds


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## SaB (May 15, 2007)

hi! I did exposed image on paper couple of days a go. 35min. with 1000w halogen lamp. crisp and perfect...


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