# I have one 90 watt bulb. How long should I expose my screen?



## jsfarney (Dec 26, 2009)

Hi, I bought the Daizo Photo Emulsion kit, and I have one 90 watt bulb. How long should I expose my screen for? Thanks for the help!


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## astewart (Dec 21, 2009)

this might be helpful, you will probably need to look into a better light source... you can get a 500w photoflood with a standard base and a rated fixture for $20... try your local bulb supplier.

[media]http://www.kiwo.com/Articles/Correct%20exposure%20time%20of%20stencil%20and%20Equipment%20limitations.pdf[/media]


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## PositiveDave (Dec 1, 2008)

That's a bit small! try getting a bigger bulb and doing this:
http://www.t-shirtforums.com/t-shirt-articles/t106506.html


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## Paul204 (Apr 21, 2007)

I started out in my basement with a speedball kit and a 100w incandescent bulb. Took about 40 mins to burn a thin stencil. You could give it a shot if it's just for hobby stuff, investing in a better light otherwise would be best.


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## jsfarney (Dec 26, 2009)

Thanks for the help. I tried burning an image, and when I took it out after 45 minutes, I could not wash out the outline of my drawing. It was colored kind of yellow when the rest was colored blue, but it would not wash out. Could it be that my printer does not print on the transparency dark enough? I also thought that maybe the lightbulb created too much heat because I put aluminum foil around it. What do you think happened?


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## RichardGreaves (Nov 7, 2006)

jsfarney said:


> I tried burning an image, and when I took it out after 45 minutes, I could not wash out the outline of my drawing.
> 
> It was colored kind of yellow when the rest was colored blue, but it would not wash out. Could it be that my printer does not print on the transparency dark enough? I also thought that maybe the lightbulb created too much heat because I put aluminum foil around it. What do you think happened?


You can see that your bulb is exposing your stencil because of the diazo color change.

Exposure is easy. If the image doesn't wash out and holds in the mesh, something cross linked it. If something cross-linked it, your positive failed to stop UV energy like a bad raincoat.

Next time you expose any screen, test if your positive completely stops UV energy. Tape a dime (or any thin coin), or a piece of aluminum foil to the stencil to see if the dark areas of your positive are failing you and letting UV-A energy through to the stencil.


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