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  1. #1
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    Default A variety of printing problems

    Hello

    I've been reading up here for a long time and am pretty new to screen printing, having done it here and there in a crappy way in the past I've been trying to get things right this time. I've read so many peoples posts on this kind of thing to try and figure it out, but no joy. I must be doing the same old wrong things somewhere but I can't figure it out.

    I've got a diy vac table, I'm using 40x30" aluminium frames. 120 mesh ( think that translates to about 300 in America, maybe). I'm using Daler Rowney System 3 acrylic with their print medium. On this print it's yellow on black paper. This is the first of two colours, white mixed with process yellow, the other being black. These are A2 prints. My squeegee is the width of my paper. I have 3-4mm off contact.

    I know I'm asking for trouble printing yellow on black, but err it's out of my hands. I'm hoping to avoid getting the separations re printed to accommodate doing a white base though as it'll cost another 60 quid and thats just the half of it.

    So as you can see in the pictures, I'm getting ghosting, blurring, areas not printing properly... basically everything is going wrong.

    I've been flooding in between strokes, but it looks like the ink isn't rolling across the screen as it should. I flood from the top downward and only the top half looks like it's covering the stencil entirely and the bottom half is exposed. Should the flood completely cover the screen and the stencil openings? Mine is very inconsistent. I try to let the squeegee glide over it, but it feels like it gets stuck and drags half way because all the ink has transferred to the top half.

    At the same time I think I'm getting through way too much ink. I did around 10 prints (mostly fucked) and I've worked my way through at least a third of a 500ml tub. Seems like after the flood theres no bead of ink for me to do the stroke.

    Then when I do a stroke I get a patchy print.

    Next problem, probably related, is that after all the other problems the bottom right part of the stencil failed to come through anymore. I thought maybe the ink was drying in that part of the screen, the medium is supposd to slow down the acrylic drying but I'd already added the reccomended 50% maximum. So I added a bit of water to my ink, didn't help much. So at this point I washed it out ready to start again. I think it could be to do with my shitty flood.

    The mesh is quite fine but its all I have to work with at the moment. So going lower isn't really an option, plus I tried an old 40t screen I used from a while back and it had similar problems. So I'm thinking that's not the real problem.

    This has been driving me insane for the past 4 days. Any help would be much appreciated. Please!


  2. #2
    Premium Member
    epicproblems's Avatar

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    Default

    As for the ink not coming through in places, try washing the shit out of your screens after you expose them, and then dry them horizontal. If you don't wash all the emulsion off it can drip/flow into open areas of the stencil and dry there. It's called "scumming" and for about 5 months I though I was having an "ink drying in" problem when really it was the scumming. Turns out, at least for me, ink doesn't dry in the screen as fast as I thought. Be sure to even wash the hardened emulsion areas of the screen a good bit. I under-washed because I was worried about washing the hardened emulsion off, but if you exposed correctly it shouldn't wash out.

  3. #3
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    Default

    Cheers for the reply.

    I can't see any emulsion in the screen, also I pulled some other prints that do print fully, but as I got further, the prints got worse and I got that nasty patchy stuff. But I'll give them another good scrub tonight to make sure.

    Hmmmmm

  4. #4

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    I was having the exact same problem with the lower right in my last print job. Can't say that I've fully resolved the problem (we'll see when I try my next job) but here's the things I did that got me through:

    1. I use simple screen hinges without any kind of weighting. I found that one of my screens was slightly warped and sitting higher in that lower right. To get through I plopped a brick on the screen at that corner for every pull. Not ideal, but it worked.

    2. You mentioned flooding. As a newbie to printing myself as well I've found that flooding technique is hugely important. I flood from bottom to top and make sure that the whole stencil is coated evenly. Focussing on that has been huge for me to get more consistent prints. I also have made the mistake in the past of keeping inconsistent globs of ink on stencil which resulted in pushing too much ink through in the pull and getting ink on the underside of the screen. That sucks when that happens.

    3. At one point I also just resorted to doing 2 pulls to cover the bad spots. Not ideal, especially if you're doing fine detail text (as I was) because the difference in ink coverage is super noticeable. Some text looked bold and the rest looked book. Not good.

    I will venture to say that your troubles reside in flooding technique. What helped me was to go on YouTube and watch a bunch of process videos to see how other people were doing it.

  5. #5
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    Andymac's Avatar

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    Default

    flood with a bit of pressure, and flood back pushing at the same angle you print with. (squeegee handle towards you) it shouldn't be thick, that's a whole other technique for when you start to get a buildup of dried ink on your screen. if you are running out of ink on the flood, you either don't have enough, or you aren't pressing hard enough.

    If you miss your flood and gob it on and try to do it a few times, you will get blurring.

    if that missing print spot is in the same place, is your table surface got a dip in it? needs to be flat.

    and is your squeegee sharp? if it is hard and rounded, you will have trouble printing and flooding and getting a nice print.
    Andymac

    services www.squeegeeville.com
    equipment www.tmiscreenprinting.com

    Todo es empezar.

  6. #6
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    Default

    Andrewrench & Andymac thank you.

    Yep squeegee is a hard edged green blade, it's hard but sharp.

    I had better results doing a pull flood and push stroke but I'll try both ways. I think you're right Andy, I'm not pressing hard enough on the flood, infact I'm barely pressing at all and trying to get the squeegee just skim it.

    I did try and reflood too, which is when I resorted to gobbing it on. You're right I got ink on the underside and blurring after that.

    Table is flat. But I'll double check how to the screen sits either side. I've got some pennies to give me the off contact at the side nearest me. Maybe I'll put some weight on like you said Andrew.

    I thought also it could be to do with my print pressure being off on my right hand... but I think it's just my crappy flood. I think you guys have confirmed this! I got some retarder today too, I might try a bit of that and see what happens.

    Also, thanks so much for the vac table Plans Andy, they were great. I read in a post you wrote that someone used a hydroponic fan and I used one of those. Works really well and I don't have to worry about noise at night/ my girlfriend going nuts. Although the brown stains on the bath from a combination of emulsion and bleach have pretty much countered that.

    Cheers all

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