# Ink not coming through screen properly



## blueskies_tees (Aug 9, 2007)

Hi,

I'm new to these forums but I can't seem to find an answer to my problem. Me and my boyfriend own a 4 press screen printing machine and we've had it for a while, but seem to get a reoccuring problem with ink going through the mesh on our screens. 

We expose the screen, tape up all the bits at the back and put the ink on. We flood the screen and test it on paper, but when we transfer the ink with the squeege some of it comes through but not all of it. It's almost like lots of the mesh is blocked. When you hold it to the light you can see that lots of the holes seem to have a slight transparent blockage in them, it's really strange. it's probably something really simple but we have no idea cos the only training we had was 2 hours with the guy we brought the machine from.

We're using plastisol ink, exposing the screen for 5.5 - 6 mins, and it all seems to come out fine. If we then take the ink off and blast it through with water again and put on a little white spirit it gets a little better but more often than not, there's still blockages in some of the holes. I think we're using 42 mesh screens.

Any help would be great! Many thanks!


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## wickedprints (Aug 9, 2007)

Ok lets see if i can help. 
If your describing things correctly you may have a screen problem... you may not be exposing the screen properly . screens work like this, lower mesh = more ink. in your case a 42 mesh count the ink should be pouring threw with no problem. you may need to adjust your exposure time on your light machine. hope that helps


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## blueskies_tees (Aug 9, 2007)

ok, so at the moment we're exposing them for 5 and a half minutes to 6 minutes, is this right? What would you recommend?

The only thing we thought might be wrong would be our ink was too thick, the new pots we've brought seem to be thicker than ones we've had in the past but I don't think it makes a difference.

Thanks for your post though


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## wickedprints (Aug 9, 2007)

First what type of light source are you using?? that makes a difference.
seconds what are (pots). Sorry dont know the term. The ink thickness would not even matter with 42 mesh screens. Dont get me wrong thickness of inks and screens are important but that another discussion.


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## blueskies_tees (Aug 9, 2007)

we're using a floodlight type light, we hold it up above the screens when we're exposing them, we don't have it on a stand. Do you think we need a better light source? It's quite a strong light, it's the type you have as security lighting outside a house, that type of thing.

By pots I mean the tubs the ink comes in.


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## wickedprints (Aug 9, 2007)

ok now we are getting somewhere. You definitely have an exposing problem and might need alittle more guidence then what i can give you at this forum. visit this link U.S. Screen Print & Inkjet Technology this will put you back on the right track. Dont worry your
problem is one that almost every screenprinter has had starting out. good luck.

paul
wickedprints


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## blueskies_tees (Aug 9, 2007)

Thats great i'll look into it!

Many thanks for your help!


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## neato (Mar 21, 2006)

Yep, that's a weak light source and not enough time at all.

When I started, I used Ulano QTX, which is an ultrafast emulsion, and a 500w worklight. It took 15 minutes to burn a screen. Ouch.

Now we use a 500w Metal Halide and burn screens in 1:25. That's because this is the right type of light. 

When you underexpose a screen, the emulsion doesn't get hardened completely. So when you go to wash out the screen, you're emulsion runs and forms a skin over the image area.

Sometimes all it takes is a damp cloth to clear the image area. But be careful, an underexposed screen is weak and using a damp cloth could couse you to lose some edge definition on your image.


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## blueskies_tees (Aug 9, 2007)

Excellent, i think I need to invest in a better light and get it fixed up properly.

Thanks for the advice


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## neilburd (Aug 9, 2007)

once in a great while i will get a clear film on the mesh that won't let ink pass. i found that if i clean all the ink out of the screen and gently rub the spot with water and dry it really good it has helped. i think it is caused by hard water and not drying the screen enough. Maybe try this if getting a new light source doesn't do the trick.


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## macmiller (Jul 23, 2007)

we've called it "scum" for years. you definitely need a stronger light source but in the meantime, expose them longer and make sure you wash out both sides very well. if the ink side has a slimy feel to it, keep washing. that slime is what's drying up in the screen, blocking the print.


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