Problem with screen sticking briefly to poster paper, leaving a mark
I am new to screen printing my posters. Still trying to get a hang of it.
I am printing an 18 x 24 poster. At the top is a large colored area.
My problem is the screen briefly sticks to the paper. It releases after a half second, but it leaves a kind of halo mark where the screen was kissing the paper for too long. It looks like S_ _ t.
Tension of squeegie against screen
Speed of squeegie
consistency of ink
tension of screen
size of screen wich is rather large, 47 x 55.
This is a second coat of ink on the paper through the screen. I didn't like the way it went down the first time, so am going over it. Not sure if the original coat (which is totally dry. It had been sitting for over a month) is making a surface that is aggrivating this situation.
TW Graphics waterbased ink (not flat ink, just normal)
I have an old Filbar semi automatic press, with a vaccum table which I mask off with taped down sheets of paper on the area that my poster does not cover.
Is there a common cause for the quick sticking of a screen down on sticky wet ink? I did a quick search of the forum but didn't see an answer.
angle your image so the squeegee is not hitting the entire area flat on. this way the squeegee starts in a corner and the paper can stay sucked down on the table to give you a proper peel.
If the screen is slack that can make it stick. Assuming you have dialed up your lift and have your peel on (do Filbars have peel?) and have blocked all the vac holes at the back, which can suck the screen down.
You might want to check your table - if the press is really old, the vac may be suspect, and/or the holes at the part where the problem is are clogged. Take a pin or nail or even use a drill to clean them out.
Add some peel or if you can't add some more lift. Speed up your stroke. Even with the paper blocking out the extra vacuum holes, make sure your screen isn't getting suck down to the bed. If you have very tiny unprinted borders increase their size. IF you cannot increase their size then you may have to make what we call a safety belt to break the ink tension as the screen peels. A safety belt is a strip of thin paper that is taped on one edge to the bed and the other edge goes over the back edge of the paper border. This strip runs the whole length of the paper. It can be annoying sliding the paper under this strip so if you bend it up slightly it makes it easier. Sometimes you need one of these in the front too.
Last edited by squeegeethree; 04-30-2013 at 09:29 AM.
It's a flap of paper that goes on top of the paper you are printing. As the screen goes up it holds down the paper just long enough to break the ink tension between the print area and the screen. We only ever have to do the with thinner paper stocks that are getting nearly full coverage. If we were doing the same paper and ink but the borders were say 2" or larger then we wouldn't have to use the flap.
No peel on a Filbar. Are you kidding?
I had one if those things I got for free, a big one, and it sat unused in my space for 15 years before I cut it up for scrap. Andy, I think you saw it.
I'd just add to what these guys said, that a dull squeegee can be part of the problem. Usually when this happens to me it's some combination of screens getting loose and squeegee getting dull. And if you haven't reamed out the vacuum holes, definitely do that, with a pin vise and a jeweler's bit. It takes forever but can make a huge difference.
Wow, the whole thing about the safety belt was interesting. I was just doing some album covers for record store day and I had a super small border all the way around. I was printing metallic ink, tons of coverage, and the paper kept sticking to the screen no matter what I did. At first I was figuring it was the ink, or not enough off contact, but whenever I ran test prints on larger sheets of paper they did fine. I finally decided that my border was way too small for the amount of ink coverage and ended up doing a bastardized version of what squeegeethree described. It was annoying as hell, and slowed me down, but it worked. I'll bet if I would have rotated my image on the screen like Andy said that would have helped as well.
yeah, that screen rotation is really good if you have a big coverage all across the top where the squeegee strikes. Just have to remember to do it (I forget and then remember after i pull the first print, then have to make flaps)
what, no peel on a Filbar? next you will tell me you can't switch from flood/print to print/flood.....