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screen printing => Waterbase and Discharge => Topic started by: ScreenPrinter123 on July 16, 2013, 01:43:16 PM
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So, I have a bunch of shirts when we ran dc tests a while back and I have a customer wanting a shirt color that doesn't discharge well, but I think I could possibly get away with a base and then dropping plastisol colors on top as opposed to doing the plastisol base and plastisol on top of that. What I want to do is take the shirt that I have a sample area of the base discharged on and print a lemon yellow on top of it. Now, the base has already been discharged for months, so my question is will the results be any different that when you print plastisol on top of the wet base on press during production? Will I get a true representation of what the yellow will look like?
Thanks.
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It will look similar but actual production may be very different. To imitate what you described as a sample exactly you would need to fully discharge and dry the UB on press, not recommended. I would just mix up a little bit of your DC UB mix and do a quick swatch test for them. You could take the time to hone the actual production sequence ahead of time while yer at it. The last thing you want to do is get a sample approved that will eat up way too much press time reproducing.
We haven't done a ton of the DC UB thing here but where we have I find we need to get some water out of the DC UB before hitting the top colors for an optimal print. Not a full discharge, just need to dry it out a little. The plastisol seems to "sink" into the totally wet DC UB. Others have achieved this putting plastisol on the totally wet DC UB but we haven't dug in enough to tweak it yet.
Let us know how you fare with it.
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I'd really recommend setting the whole thing up just as you'd run it, on the garments/color you'd be printing.
Bright yellow is a transparent color by nature, so your ground must be pretty well discharged
to get a bright yellow. Or use an opaque yellow on top.
Discharge underbase plastisol top is actually one of my favorite ways to print. The end result is
somewhere between the heavy hand glossy plastisol printing and the super matte softness of waterbased.
I really really like it.
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Yep, yellow is a pain in the arse with coverage, I would absolutely use a HO Yellow for the top color, presuming it's the only color or printed last of a WOW set of colors.
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How much do you guys usually choke the underbase for discharge printing with plastisol top colors?
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What mesh count are you using for the discharge base? I would assume too much base down and it would be too wet to cure well but too little the base may not be bright enough.
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How much do you guys usually choke the underbase for discharge printing with plastisol top colors?
Not to brag , but my press wholes good registration so I can run butt reggie most times, although I might at times choke a 1/2 point.
Darryl
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Discharge base 230, White 230 WOW, Flash then a yellow or the rest of your top colors. It is the brightest yellow you will ever get. This works perfect for neon's as they are even more transparent.
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Same choke as plastisol typically.
No choke Darryl?! damn, that is some good reg.
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Perfect reg. still need atleast a 2 pixel choke with a discharge underbase, discharge tends to gain just a little and if you don't like that white peaking choke 2 pixels.
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I don't find DC/WB to gain nearly as much as plastisol does. But DC/WB is printed on contact with heavy pressure, plasti is off contact with bare minimum pressure. That give us reg issues, especially on the gauntlet with all that platen deflection on the outside of the press. A choke can really help you out in knocking the job into place quicker.
So I've just treated it same as plastisol so far, 2px is pretty typical choke at 300-350ppi, 0.5 pt or so in Illy but we're set to scale stroke so that's not much of an indicator for others.
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Wow 2 px seems to be a lot, we normally go for 1 px max.
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Wow 2 px seems to be a lot, we normally go for 1 px max.
same here. 1pt for both plastisol and DC.
this is for two reasons:
-when I first started, if I did not choke, I would get the sandwich effect and you could see the underbase on the side of the print. It was not visible if observed from the top, but when shirt was turned, you could see the bottom layer.
-we have one head that's out about 5-6/1000th of an inch. If we don't add a little bit of trap, white will show every now and then. (yes, the infamous registration block MHM issue!)
pierre
p.s. also of note is the we DO NOT CHOKE! All our overprinting is trapping as it maintains the correct look of the art whereas the choke can introduce significant deviations in thin lines and small areas.
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Well keep in mind that's all relative here- a 2px choke at 600ppi = a 1px choke at 300ppi. And again, if you have your strokes set to scale with art, this is going to vary in illustrator or vector programs too as will whether or not you align the stroke to center, inside or outside. Reckon everyone is talking about 1px at 300-350 ppi though.
I find it really varies on the specific job for me as to how much I'll choke the UB or spread the top colors.
I don't know why but I always mix up choke and trap, do we use it differently in screen printing than in other formats? In my head: choke= decreasing the outer edge of an image and trap = spreading out the outer edge of an image to overlap with others.
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-we have one head that's out about 5-6/1000th of an inch. If we don't add a little bit of trap, white will show every now and then. (yes, the infamous registration block MHM issue!)
If it was the blocks you would have issues with a certain pallet(s) rather than a certain head. And it would almost never be just one.
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-we have one head that's out about 5-6/1000th of an inch. If we don't add a little bit of trap, white will show every now and then. (yes, the infamous registration block MHM issue!)
If it was the blocks you would have issues with a certain pallet(s) rather than a certain head. And it would almost never be just one.
I meant platen, thanx for catching that. there are two more that are out 2-3/1000th of an inch, but that is really not visible on most prints.
pierre
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Got it, just wanted to make sure you weren't chasing ghosts.
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Are you guys running your shirts with the dc base through the dryer the same speed as straight discharge or are you speeding it up a bit, running my discharge at 360 degrees for 2 minutes currently.
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Are you guys running your shirts with the dc base through the dryer the same speed as straight discharge or are you speeding it up a bit, running my discharge at 360 degrees for 2 minutes currently.
we are slowing down the belt, but keeping the temp the same.
pierre