Author Topic: On press issues I need help with  (Read 2008 times)

Offline Appstro

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On press issues I need help with
« on: April 07, 2014, 10:56:47 AM »
I have two issues I need help with if you would :)

#1 I did a job this weekend that was simple - I thought.... Its a word in red with a white outline in a charcoal shirt. I approached this job by making the white a full underbase and just making sure that the red was centered in the white outline. I used a 110 screen for the white and a 160 for the red. Both colors are a solid hit. After I got started I noticed that the red was not "sharp". I may have done my last coat on the wrong side of the screen. So I was thinking that might have caused it. I could feel the thickness of the emulsion on the ink side of the the screen... any way...This issue caused me to stop ever so often and wipe the underside of the red screen to clean up the "blow out" that was occurring occasionally. Thats where the problem began. After the job was done I inspected my shirts and some were noticeably pink in the outline. I have a jewelers glass and looked closely at the white and saw red ink. Even though I used screen clean when wiping down the red somehow the red transferred to the white. What did I do wrong and how can I avoid this?


#2 I did another job this weekend. This job would certainly be easy! Its only white ink on a sapphire colored shirt. One hit per side 160 shirts. Easy right? Wrong... The one hit wasnt working. The logo is a schools name and a large solid white paw in the middle. When doing just one hit of white I could clearly see the shirt color under the ink. The school probably would not care but I wanted to do my best so I tried just doing two hits without a flash. In hind sight this would have been the way to go I think, however the shirt color was still visible. So I decided to hit flash hit. The shirts looked great. I used a shitload of white which I underestimated using. The PROBLEM.... After I got going my plattens starting heating up. I have a 6/2 so I was doing one hit, rotating to the flash loading, doing one hit, rotating, doing the second hit, unloading, loading and doing a first hit and rotating to the flash, etc.. WELL after a while my screen clogged up. This kept happening over and over again. Of course every time I opened the screen up it made a big mess and the ink would get messed up and the shirts etc.... I ended up using what screen opener I had left and had to stop. I had run out of screen opener and white ink! I still have 60 shirts to do. It took me 3 hours to do 100 shirts. at the last minute I decided that a fan would help and it did, but I still had issues. The fan which was over sized for the task, would cause ink "stringers" and make more mess...I guess it was too close and too high speed for the job. The screens still clogged a bit. I also see that now my plattens are just a wee bit dish shaped from the heat I imagine :( What did I do wrong and how can I do it better next time??

Thanks for your advice everyone! I do love this place!


Offline ScreenPrinter123

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Re: On press issues I need help with
« Reply #1 on: April 07, 2014, 12:31:43 PM »
I have two issues I need help with if you would :)

#1 I did a job this weekend that was simple - I thought.... Its a word in red with a white outline in a charcoal shirt. I approached this job by making the white a full underbase and just making sure that the red was centered in the white outline. I used a 110 screen for the white and a 160 for the red. Both colors are a solid hit. After I got started I noticed that the red was not "sharp". I may have done my last coat on the wrong side of the screen. So I was thinking that might have caused it. I could feel the thickness of the emulsion on the ink side of the the screen... any way...This issue caused me to stop ever so often and wipe the underside of the red screen to clean up the "blow out" that was occurring occasionally. Thats where the problem began. After the job was done I inspected my shirts and some were noticeably pink in the outline. I have a jewelers glass and looked closely at the white and saw red ink. Even though I used screen clean when wiping down the red somehow the red transferred to the white. What did I do wrong and how can I avoid this?

A thin stencil could cause this as you need a wall to keep the ink from squishing outside of the stencil.  I would also suggest a higher mesh count with a fast squeegee stroke with a near vertical squeege.  Try something around a 230 for printing on top of a white underbase.

#2 I did another job this weekend. This job would certainly be easy! Its only white ink on a sapphire colored shirt. One hit per side 160 shirts. Easy right? Wrong... The one hit wasnt working. The logo is a schools name and a large solid white paw in the middle. When doing just one hit of white I could clearly see the shirt color under the ink. The school probably would not care but I wanted to do my best so I tried just doing two hits without a flash. In hind sight this would have been the way to go I think, however the shirt color was still visible. So I decided to hit flash hit. The shirts looked great. I used a shitload of white which I underestimated using. The PROBLEM.... After I got going my plattens starting heating up. I have a 6/2 so I was doing one hit, rotating to the flash loading, doing one hit, rotating, doing the second hit, unloading, loading and doing a first hit and rotating to the flash, etc.. WELL after a while my screen clogged up. This kept happening over and over again. Of course every time I opened the screen up it made a big mess and the ink would get messed up and the shirts etc.... I ended up using what screen opener I had left and had to stop. I had run out of screen opener and white ink! I still have 60 shirts to do. It took me 3 hours to do 100 shirts. at the last minute I decided that a fan would help and it did, but I still had issues. The fan which was over sized for the task, would cause ink "stringers" and make more mess...I guess it was too close and too high speed for the job. The screens still clogged a bit. I also see that now my plattens are just a wee bit dish shaped from the heat I imagine :( What did I do wrong and how can I do it better next time??

When you clean a screen I would suggest doing a test print to make sure there is no haze or smudging around the edges of your design indicating the screen was not fully cleaned.  It also sounds like your shirts are spending too much time under the flash.  Try turning down the heat of the flash, adjusting the height of the flash, or decreasing the amount of time the shirt is under the flash.  It should only be there long enough to gel the ink.  The ink should be dry to the touch after flashing, but if you over flash it will become tacky which you want to avoid.

Thanks for your advice everyone! I do love this place!

Offline mimosatexas

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Re: On press issues I need help with
« Reply #2 on: April 07, 2014, 12:54:26 PM »
My suggestions:

#1:
Ideally use 3 screens instead of 2, and flash between each print.  Use a 160-230 for the first screen, and use white ink.  Flood, hit once, do a clearing stroke with no ink, and flash.  Next print your red.  Use a 230+ for the red, flood lightly, instead of hard, and hit it once with as quick and light a stroke as possible to clear the screen.  low pressure, quick stroke, high mesh, and soft flood will all help combat the blur/gain that you experienced.  If you could feel the stencil on the squeegee side of the screen, you likely dried the screen the wrong way up.  Now print the third screen, another white screen.  Use whatever mesh you want, but higher is better.  If you want to only use two screens, you can stick with the 110 for your white base, but you should print/flash/print and it is VERY important that your strokes are clean and the ink is nice and smooth.

#2:
A one hit white is basically a myth unless you really understand ALL the variables going on and have full control over them.  For now, always assume white on a dark shirt is print/flash/print.  Do not print, flood, print without flashing between, or you will experience massive blurring and dot gain and the fibers of the shirt will still show through, plus the print will feel like a giant plastic film on the shirt.  You can also use a higher mesh screen when you p/f/p and use less final ink so you save money and have a better feeling print.  As for the flash heating up your platens, I am assuming you have a 6/2 silver press with MDF platens.  I used the same press for multiple years and the best way I found to combat the pallets getting absurdly hot was to alternate between pallets every dozen shirts or so, and have a fan cooling the other pallet off during that time.  In other words, pretend the press only has one arm, load, print, unload on just the arm for a dozen shirts, with the flash near you for control, then when it is too hot to use, switch to the other arm.  it isn't as fast, but it gives you a lot more control and will fix the mdf heating up issues.  I second the idea that you may be overflashing as well.

Offline screenxpress

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Re: On press issues I need help with
« Reply #3 on: April 07, 2014, 10:32:37 PM »
making the white a full underbase and just making sure that the red was centered in the white outline. I used a 110 screen for the white and a 160 for the red.

full underbase .  This sounds scarey to me.  I make my underbases about a 50-65% halftone so I don't create a bulletproof print and of course the white outline would be full white, not halftone.  The underbase is supposed to create an opacity layer for the top coat.  I also didn't read anything about flashing on this project.  Did ya?  I would be at about a 160 underbase and at least a 195-230 on the Red.  Certainly not 110.   For this job, I'd be doing a P/F/P/F on the underbase (white) and then the Red on top.  I never (did I say that?) have to wipe the back of a screen during printing.  Even when doing a sep print.  That's a slippery road and  will generally either cause some chemical migration to the ink on top or leave a film across the bottom side that is sure to cause issues.  That's my story and I'm sticking to it.
Anything important is never left to the vote of the people. We only get to vote on some man; we never get to vote on what he is to do.  Will Rogers

Offline Appstro

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Re: On press issues I need help with
« Reply #4 on: April 08, 2014, 05:01:36 PM »
That's exactly what happened :) " chemical migration to the ink on top or leave a film across the bottom side that is sure to cause issues"
I just did a solid white, flashed and then the solid red on top and sent er' through the conveyor...