Exposure help speedball&500w light

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speeder
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Exposure help speedball&500w light

Post by speeder »

Hey names matt first time posting. Im having a problem getting my image exposed onto the screen. Im using speedball photemulsion and a 500w light bulb lil more then 12 inches away. I exposed it for about 5 minutes. When i tried to was out the screen the image would not come fully out. I had let the screen dry for 48+ hours. I think i might not have exposed it long enough or i let the screen dry for to long. ANy idea what kinda exposure time i should use?
squeegeethree
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Re: Exposure help speedball&500w light

Post by squeegeethree »

As long as you had the screen drying in a completely dark room, we can rule out letting the screen dry too long.
It sounds like your screen is over exposed.
1. Did you develop/wash both sides of the screen. You should, paying special attention to the side away from the light.
2. Was your film opaque or were you using something less so like xerox on acetate.
3. Was your film in perfect contact with your screen during exposure or were there gaps allow light to "leak" around your film.
speeder
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Re: Exposure help speedball&500w light

Post by speeder »

Yeah both sides were covered.
was using overhead projector film with very dark image.
film had glass on top to keep it down.
light must have gotten to it somehow?
squeegeethree
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Re: Exposure help speedball&500w light

Post by squeegeethree »

Decrease your exposure times. Or better yet do a step test.
speeder
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Re: Exposure help speedball&500w light

Post by speeder »

I burned another screen. Tried less time but still didnt want to wash out. So i used a brush and it finally came through. I think perhaps i dont have enough activator in the emulsion.
squeegeethree
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Re: Exposure help speedball&500w light

Post by squeegeethree »

Emulsion usually comes with all the "activator" that's needed. You're supposed to add it all.
johndoh
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Re: Exposure help speedball&500w light

Post by johndoh »

I have used ulano RLX for a long time. Very forgiving, wide exposure range, eg with the right positive 5 minutes or eight minutes doesn't really matter. Just a tip if you are struggling with dodgy exposure units and lights....get some spray adhesive, glue your positive on and simply stick it out in the sun. may take some testing but 30 seconds to a minute is about the norm. Maybe put something black at the back of the screen and keep the exposure side facing the sun as you quickly race it in and out...it works a treat and it's simple. I used this method for a long time even though i had an exposure unit....bloody lazy I guess.
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Re: Exposure help speedball&500w light

Post by johndoh »

Forgot....wash excess glue off screen with turpentine before washing out in water.
wes
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Re: Exposure help speedball&500w light

Post by wes »

from what I see it is 1 of 2 things exsposure time to long or you did not mix all sensitizer into emolution.. I use a 1000w HPS light (not the best exsposure unti I know) and I expose for aptox. 2 - 2min 30 sec and image blows right out.. I also use ulano emolution really good and stable product
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