# Halftone



## Mproviders (Jan 17, 2014)

Hello I'm new to this screen printing, made a halftone shirt but all the image didn't come out. Im having issue when it comes to the exposure.


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## TYGERON (Apr 26, 2009)

How did you go about calculating the exposure time you used?


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## Mproviders (Jan 17, 2014)

I used 5 min exposure time, most of the image came out but not all of it and the back of the emulsion was slimy.


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## Printor (Apr 16, 2015)

What type of light source are you using? What mesh of screen? What LPI was the film done in. Where you getting simpler images on screen with the same steps?


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## TYGERON (Apr 26, 2009)

Mproviders said:


> I used 5 min exposure time, most of the image came out but not all of it and the back of the emulsion was slimy.


 How did you come to doing 5 minutes?

What I'm getting at is it sounds like you're guessing 

If your emulsion is "slimy", you're underexposing and depending on your set-up, you may be getting uneven exposure.


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## Mproviders (Jan 17, 2014)

I never did a exposure test, i bought the exposure unit off someone and they got it from Ryonet and the unit says to expose 5min. It shouldn't have any slim at all? I think 5mins is for spot process and not halftone.


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## DigitalMayhem (Aug 4, 2007)

You have to experiment to find the best time. There is no set in stone time. 5 min may have been perfect when the bulbs were new. I just replaced all 11 bulbs in my megalight and was able to cut my times almost in half. If it's slimy it's underexposed like they said. 

Sent from my 831C using T-Shirt Forums


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## TYGERON (Apr 26, 2009)

Mproviders said:


> I never did a exposure test...


Too many variables, different emulsion types, mesh counts, light sources, humidity, distance, film etc.

Eliminate guess work, save some time and emulsion. 

Do an exposure test. Do it often as variables change.

You may have more experience but check this thread:

http://www.t-shirtforums.com/screen-printing/t548842.html#post3008658


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