Halftone w/ underbase advice (waterbased)

4745 Views 24 Replies 5 Participants Last post by juanftm, Sep 1, 2010

juanftm

Discussion Starter · Aug 31, 2010 (Edited)

5

Hey all,

I am having some problems printing a 2 halftone image with white underbase onto standard ultracotton guildan shirts.

My underbase is printed through a 156 mesh, i'm using opaque white, and i'm doing print flash print flash. the halftones are both on 230 yellow screens using a black and a green ink.

all the inks are water based.

Now the issue is basically that if I print the halftone (either the 1 or the 2 together) the image looks ok, albeit a bit dark. When I print the halftones on top of the underbase, the image looks like poop. I'll try to post some pictures.

Any advice??

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Swagger11

· #2 · Aug 31, 2010

Someone correct me if I'm wrong but, unless your printing to black or dark shirts you probably dont need an underbase. From the examples you posted looks like your printing on white tees correct? Try it without the underbase and see how it comes out.

juanftm

Discussion Starter · #3 · Aug 31, 2010

Hi, Thanks for your reply, this was just a test shirt. They print will go on dark shirts.
Juan

Swagger11

· #4 · Aug 31, 2010

Okay so you may want to test it on a dark shirt then, so you can see how it will look on a dark garment. It may look different and you may not have the same issue your having with the light tee. Can I ask why your practicing on a white tee if your gonna be printing on dark tees?

juanftm

Discussion Starter · #5 · Aug 31, 2010

My question is more about how the halftone is losing it's characteristic smoothness when I print on top of the underbase. If I'm printing with an underbase it should look the same on a dark as it would on a light shirt, no?. I'll definitely try it on a dark shirt this afternoon just to make sure.

Swagger11

· #6 · Aug 31, 2010

I agree that it should not lose any details or smoothness on the halftone, but I would still test on a dark garment to make sure your having the same issue.

CNClark

· #7 · Aug 31, 2010

I would suggest underbasing without a the p/f/p and adding a highlite white. All you are trying to do with an underbase is get a grey color, you don't need it to be white if you add the highlite. The less ink the top colors are sitting on the better.

CNClark

· #8 · Aug 31, 2010

IT could also be too much pressure on the squeegee when printing, or not enough off-contact as well....and make sure your squeegees are sharp.

juanftm

Discussion Starter · #9 · Aug 31, 2010

CNClark said:
I would suggest underbasing without a the p/f/p and adding a highlite white. All you are trying to do with an underbase is get a grey color, you don't need it to be white if you add the highlite. The less ink the top colors are sitting on the better.

Thanks. Do you guys think the 156 screen is adequate for the opaque white underbase? or should i go with finer mesh?

juanftm

Discussion Starter · #10 · Aug 31, 2010

CNClark said:
IT could also be too much pressure on the squeegee when printing, or not enough off-contact as well....and make sure your squeegees are sharp.

Thanks, do you guys think the 156 screen is adequate for the opaque white underbase? or should I move to a finer mesh?

ShirlandDesign

· #11 · Aug 31, 2010

I just worked like crazy to get the half tone part perfect, then tried putting it on a white under base. Looks like junk. I checked all the search posts on underbasing a half tone, and no luck. I'm going to an index sep., but if there is a good solution I'd love to know about it.

CNClark

· #12 · Aug 31, 2010 (Edited)

juanftm said:
Thanks, do you guys think the 156 screen is adequate for the opaque white underbase? or should I move to a finer mesh?

I would consider that too coarse of a mesh for underbasing in my shop. Normally we halftone our underbase at around 80% and use a 180/55 or 225/48 mesh count...depending on the detail needed. If you can get away with printing the top colors with a 300 mesh, that might help. Hard to say what exactly the problem is since there are so many variables.

And remember opaque underbasing is not what you are after....the opaqueness(is that a word?) comes from the top colors.

Also , the highlite white is not just used to make the white pop, it can also be used to soften the gradients.

ShirlandDesign

· #13 · Aug 31, 2010

CnClark, I take it that you successfully half tone on an under base? Would you mind itemizing the numerous variables you keep in mind to successfully execute?

CNClark

· #14 · Aug 31, 2010

Sure, here's a few...

Mesh Counts- I prefer 180 or 225 for underbasing..you are not trying to get an opaque underbase, a reduced white or grey color is used so that when printed, the fibers of the shirt lay down and you get a medium gray non-opaque underbase. I also underbase at 80%, so the underbase it made up of halftones.

Angles-Set halftone angles to 22.5 on all screens, this will help control moire.

Ink-you need to play with your ink and reduce the underbase so that you still get brilliant top colors, but your laying down as thin an underbase as you can to achieve the brilliant top color. Highlight white is not only used to make a brilliant white, it is also used to soften the gradients. In my shop we routinely print white ink on white shirts and black ink on black shirts just for that reason.

Dot Gain-Inks inherently spread on press, sometimes up to 20%. To control this, you pull back the amount of color in the seps. If you print the first strike-off on a white shirt and it looks like the original image, your gonna have problems when the production run starts because of dot gain. A good test for this is to wipe down the back of the screen with a dry rag real well...then print on a fresh underbase.....if the image looks much better than before, you are seeing the effects of dot gain.

Squeegees-sharp, 75 duro squeegees is what we use.

Screen Tension-High tensioned screens are important so you can reduce off-contact and to keep mesh stretch to a minimum. Big off-contact and lots of mesh stretching equals a poor print, especially when on a manual press where everytime you push the squeegee it is at a different pressure, thus the image your printing isn't in the exact same spot each time. This may not be noticeable to you, but if the image is moving around even thousandths of an inch, then that ink movement is now on the back of the next screen, which when printing WOW, equals gain on press...

Hope this helps.

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juanftm

Discussion Starter · #15 · Aug 31, 2010

Thanks for sharing! what do you set your frequency at?

CNClark

· #16 · Aug 31, 2010

60-65 is what we normally run.

ShirlandDesign

· #17 · Aug 31, 2010

O.K....so using the underbase for the white in the print is a mistake. If I understand correctly a touch plate would be used to supply the highlights and say white outlines for the text, and you would use a reduced 80% neutral to keep the top inks off the fabric. Also, super tight press and super tight screens and super sharp squeegees. Also would you suggest a push stroke to a pull? Your help is greatly appreciated.

CNClark

· #18 · Aug 31, 2010

No, the colors need to be underbased, just not with a super bright white underbase....halftone and use finer mesh. Then use a highlite white over the areas that will have white showing. Then you will have a brilliant white, but not to the detriment of the other colors.

Tight screens, tight presses, and sharp squeegees will make your job easier always, no matter what you're printing.

Push stroke is superior to a pull stroke. Not only for ergonomic reasons, but the print will be superior as well. A crew of pushers can run circles around a crew of pullers.

I got a job wrapping up on the floor, gotta get back to work.

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Dan K

· #19 · Aug 31, 2010

If you really are printing with water based inks, the discussions of underbase and highlight whites could be disregarded. All you have to do is add the discharge activator, the same one that you are using for your underbase to the pigmented water based inks. The discharge will react in the dryer and when it comes out the other side, you should have some nice opaque prints.

Some people do print a discharge under base under water base [and plastisol] colors, but I have never heard of anyone using white water based inks as an underbase. The white water base pigments will inhibit the colored pigments, the colors you are trying to print, from penetrating the fabric.

If you're on an auto, use a higher mesh like 160 or 200. If you are on a manual, 160 could work, but you want to drive that ink into the garment. Make sure your screens are tensioned well so the ink can pass through the open areas as it should.

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CNClark

· #20 · Aug 31, 2010

Um..oops..I completely passed over the fact that the OP was talking about water-based/discharge. I was referring to plastisol...sorry bout that.

If you're discharging, obviously you are playing by a different set of rules, and Dan is 100% correct.

Happy Printing....

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