# Is this an emulsion problem?



## SuprQuik (Dec 14, 2015)

Hey guys and gals, lately I've been making screens and only 1 in 10 work. I emulsion the screen with two passes front and back rotating the screen each time. The screens are clean and degreaser and blown dried and then allowed to sit over night to dry. Then after emulsion in they sit in a dark room for atleast 24 hours to let the emulsion dry. I then burn using a 500 watt hologen bulb for 13 minutes with dark cloth under the screen, image on ink side and glass covering it. I then use a washout booth with warm water to wash the image out from a normal hose. The emulsion is wbp from ryonet. The image initially starts to washout then the positive starts to wash away with it, I can wash the whole screen off with only a ghost of the image left behind. I'm pulling my hair out, could the emulsion be bad? Only a few weeks since I mixed.


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## Ripcord (Sep 2, 2006)

Your exposure time is way too short. Try doubling that and do a step test to determine the correct exposure. Unless your design has very fine lines, it's always better to overexpose than underexpose.


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## jeron (Jul 16, 2012)

Sounds like under exposure. With those little 500 watt lights you need a lot of time. Try doubling you exposure time. Use an exposure calculator or step wedge test to get your times right

To test if the emulsion is good or bad. Coat one, then after its dry tape a piece of cardboard to the center of the screen on the front and back in the same spot. So no light can get to the spot on the front and back. Then set it outside in the sun for like 5 min. If the spot under the cardboard washes out but the rest of the emulsion is fine, then your emulsion is good and your not exposing long enough.


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## caliber1 (Feb 19, 2013)

you know you can use the sun also as an exposing unit .. I use the sun when I have oversized signs to print. but yeah what they said, sounds like under exposed screen. try upgrading to a pressure washer bro. it will help out a bunch


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## Ripcord (Sep 2, 2006)

caliber1 said:


> you know you can use the sun also as an exposing unit .. I use the sun when I have oversized signs to print. but yeah what they said, sounds like under exposed screen. try upgrading to a pressure washer bro. it will help out a bunch


I expose screens in the sun a lot. It takes about one minute and you can't get a better single point light source.


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## Kenneth59 (Sep 28, 2013)

why so much emulsion? Use pure polymer and one thin coat front and back. We use a 400w metal halide 2 minutes 30 seconds, light source 18 inches from screen.


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## artlife (Jan 15, 2010)

film positive should be on the substrate side because that's where the bulk of the emulsion should be. it's so easy to make a box with lights inside and glass on top. put screen face down with film, then you can lay black cloth on top (insulated or room darkening curtain works great) and weight it for good contact with board cut to size and/or paperback books, magazines and catalogs.
but anyway your exposure time is way too short.
without knowing how thick your emulsion is, you may be coating too thick. a high solids emulsion you can coat 1+1 (substrate side/squeegee side). thinner you can coat 1+2. very thin or low meshes can be more. Always dry horizontally with substrate side down.


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## SuprQuik (Dec 14, 2015)

Thanks everyone for the tips, your life savers. I was using a direct uv bulb before I had to move shops so this would explain it. Greatly greatly appreciated


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## Horntoad10 (Apr 28, 2019)

jeron said:


> Sounds like under exposure. With those little 500 watt lights you need a lot of time. Try doubling you exposure time. Use an exposure calculator or step wedge test to get your times right
> 
> To test if the emulsion is good or bad. Coat one, then after its dry tape a piece of cardboard to the center of the screen on the front and back in the same spot. So no light can get to the spot on the front and back. Then set it outside in the sun for like 5 min. If the spot under the cardboard washes out but the rest of the emulsion is fine, then your emulsion is good and your not exposing long enough.[/QUOTE
> 
> ...


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## Horntoad10 (Apr 28, 2019)

Sorry about that!
Thanks Jeron.....your tip was very helpful.


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## Horntoad10 (Apr 28, 2019)

Sorry about that!
Thanks Jeron.....your tip was very helpful.


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## Horntoad10 (Apr 28, 2019)

Question - where can I get an exposure calculator


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## INKOGNEETO (Feb 20, 2015)

Horntoad10 said:


> Question - where can I get an exposure calculator


Many options available online to determine exposure time.

https://smrsoftware.com/vellumexposure.php

The Free, downloadable, NeverTheLess screen printing supplies exposure calculator!


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