# Screen printing halftones



## AGR9 (Mar 2, 2011)

Hi all,
A new project means new techniques and loads more questions! Hope someone can help.

I am looking to screen-print a paint-spatter design in black onto white t-shirts. There are varying levels of opacity of the black in the design however.

As far as I can tell, I'll need to turn the image into halftones in PS or Illy before exposing my screen.

Can anyone confirm this process for me, and also any information on mesh counts (ideally UK) and any differences in exposure time would be greatly appreciated.

I've attached a piece of the image in case it helps!

Thanks, as always, in advance.
AGR


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## red514 (Jul 21, 2009)

what mesh counts do you have? the higher number the better. not sure about the T measurement (can't seem to find my conversion chart) but i recommend 280 or higher.
the lpi will depend on what mesh you choose, 200-280 i suggest 45lpi, 280 or higher i recommend 55lpi

in photoshop, you will want to convert the grayscale image to bitmap mode
mode>bitmap
use output of 300ppi or 600ppi (cleaner halftones with higher ppi)
(your input should be 300ppi, your working ppi at the size you want printed)
use halftone screen
frequency = 55lpi (or 45lpi depending on your choice of mesh)
angle = 21
shape = ellipse or dot


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## red514 (Jul 21, 2009)

are you printing manually?
before converting to bitmap halftones you may want to adjust your levels, lighten the shadow areas a bit to help with dot gain on press


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## AGR9 (Mar 2, 2011)

Thanks, a great help. I am printing manually, and will be buying in a new screen for this project. Ideal mesh count suggestions? Am I right in thinking a 280 US is about a 110 UK?


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## red514 (Jul 21, 2009)

sound right. i found this old thread
http://www.t-shirtforums.com/screen-printing/t30183.html

a 110T should be fine for you, may take some getting used to, you will probably want to reduce your ink a bit for ease of use, if it's thick.


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## red514 (Jul 21, 2009)

i do recommend exposure tests so you can capture as much detail as possible. halftones can be tricky if it's your first time exposing them.


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## AGR9 (Mar 2, 2011)

Just wanted to say thanks for all the help, it took a while to get round to even starting the project, but all worked out brilliantly with your tips.


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## red514 (Jul 21, 2009)

Good to hear!
any chance you have a pic of the final print? always nice to see printed work


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## skitten (Feb 16, 2014)

I know this is an older post but how many screens is possibly involved in the design AGR9 posted? http://www.t-shirtforums.com/attachments/24664d1311622614-screen-printing-halftones-ink-s.jpg
I am assuming a minimum of 3 since there is alot of gray areas. I hope to do designs like this when I can afford to upgrade to a 4 color press.


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## red514 (Jul 21, 2009)

skitten said:


> I know this is an older post but how many screens is possibly involved in the design AGR9 posted? http://www.t-shirtforums.com/attachments/24664d1311622614-screen-printing-halftones-ink-s.jpg
> I am assuming a minimum of 3 since there is alot of gray areas. I hope to do designs like this when I can afford to upgrade to a 4 color press.


depends on the ground colour, if it's just a white tee then 3 screens (blk, gray, lt.gray) will give you excellent results. you could do just 1 screen (just black) but the dots will be much more noticeable because of the high contrast. using at least 1 gray helps to reduce the contrast between the black and white ground giving a much smoother looking print with more depth to the design.


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## skitten (Feb 16, 2014)

red514 said:


> depends on the ground colour, if it's just a white tee then 3 screens (blk, gray, lt.gray) will give you excellent results. you could do just 1 screen (just black) but the dots will be much more noticeable because of the high contrast. using at least 1 gray helps to reduce the contrast between the black and white ground giving a much smoother looking print with more depth to the design.



Ohh I see. Would you say a gray t-shirt would be an option for cutting out 1 screen or jus depends on the design?


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## red514 (Jul 21, 2009)

skitten said:


> Ohh I see. Would you say a gray t-shirt would be an option for cutting out 1 screen or jus depends on the design?


it really depends on the design but you have the right idea for reducing colours by using the ground colour.

with the gray tshirt scenario, if your design has white in it, you would now need a white instead of the gray.


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## skitten (Feb 16, 2014)

red514 said:


> it really depends on the design but you have the right idea for reducing colours by using the ground colour.
> 
> with the gray tshirt scenario, if your design has white in it, you would now need a white instead of the gray.


i see. ok thankyou!!!!


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## FullSpectrumSeps (Aug 2, 2012)

You would want to use diffusion / index / noise dots for this artwork to print most like the original.

Using a halftone pattern with distressed imagery is the wrong approach.


Convert to diffusion at a DPI you can hold, 50, 100, 150, 200, etc and it will come out much better than a halftone version, it will be more like the original art.

Halftones for smoother gradients and artwork, stochastic/diffusion dots for more grungy/distressed and irregular art.

Sometimes the best approach is some parts of the design done with halftones and others with the diffusion. See attached.


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## FullSpectrumSeps (Aug 2, 2012)

In relation to the splitting of a black gradient into multiple greys... this is better but obviously requires more screens than just 1... attached is an example of this where you have lots of soft shades of the greyscale, detail etc... and you want the high-end or best-quality way to produce it with the most consistency and smooth look to the shades... then you use automatic techniques to pull the perfect interlcoking diffusion or halftone blends with black and grey, black and 2 greys, or only using a dark, medium etc... Many different ways you can split it, but at the most I've never had to use more than 3 greys plus black and white for the highest-end-looking greyscale print. The cool part is you can tint the greys with any color you want on-press to get the sepia or other tonal looks, even using a bright ink to make it colored. But in reproducing an original black and white... the control over the print quality can still be maintained with good enough technique and equipment, however it will sure help if you can print with more screens then it will be easier to keep the tonal-shift under control from print to print. 

For greyscale printing however, the correct method is always to interlock your halftones or diffusion patterns. If you take your greyscale separation curves, convert them to halftones all at the same angle, and then overprint them.. it will simply destroy all of the correct blending of the inks when you go to print and you'll see the angle of the dots much more, more chance for moire and a whole number of other issues. 

You simply invert one of the gradients before you convert to halftones.

If you have black and white (especially going on shirt other than white and you need to print the white ink also) -- the only correct way to produce this art on a shirt with black and white gradient is to invert one of the screens. Essentially they are perfectly interlocked halftones and it locks out your shirt color completely from affecting the design. 

When using 1 grey like a medium grey between the black and white -- then you would run the black and white at the same halftone, but invert the grey before ripping it and invert back. The halftones of the black/grey/white will all interlock perfectly.

To control dot-gain you print the dark inks before the lighter ones, with opaque inks they push each other back to the right tones automatically with the ink-sequence being your compensation technique.

This cannot be done however with just 1 black screen on white shirts (or just fading 1 screen into the shirt color) -- you will then have to control the dot-gain better on the 1 screen because there is not another being printed interlocking with it as the blend-color which pushes the tone back into the right direction because both screens gain a little. 

I've attached another example of the multi-grey method with interlocking halftones.

No matter which way you slice it... greyscale separations are best done completely automated by the math of the levels, and we have dark, medium, and light grey inks that work for the various points in a blend. You don't need to spend any time on the sep it is automatic if you know how to simply pull the curve points and halftone-convert them. (even color-range tool works good now in Photoshop CC for GREYSCALE they have added automatic greyscale pulling you can adjust the point and the ramps, easier than doing with curves but once you automate it the entire process is handled by the computer all the way to rip, you just choose your LPI or halftone method.) I understand a lot of people think color-separations are complicated and require some sort of artistic decisions, but for greyscales this is absolutely not true at all, and only occasionally true with colored artwork if there is really a reason it should be printed one way or another... with blending/process screens or spot-custom blends for the tints/shades that is just a decision like with the greyscales mentioned above whether you want to (or can) blend with fewer screens or need more to keep it consistent by using extra colors for the blends.

I noticed the thread had started talking about multiple greys for this and I wanted to share additional information and examples about it, as its not the same as the other example I showed about interlocking colors or using diffusion dots for grungy art instead of halftone patterns which become harder to hold and look too ordered or regular for the irregularity of the art. 

This is more about the expansion from 1 black, to the multiple greys. My video channel is undergoing a renovation with all new stuff going into these things, but for the time being I wanted to share when I notice something on these industry forums that I have experience with, and it will make more sense when people see actual video examples of these truly innovative and unique methods but are the apex of professional screenprint color management, separation, rip, and printing. 

Hope this adds to the discussion and helps to clarify some of the things going on with "screen printing halftones".


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## deepbluex (Jun 24, 2011)

red514 said:


> depends on the ground colour, if it's just a white tee then 3 screens (blk, gray, lt.gray) will give you excellent results. you could do just 1 screen (just black) but the dots will be much more noticeable because of the high contrast. using at least 1 gray helps to reduce the contrast between the black and white ground giving a much smoother looking print with more depth to the design.


This. I totally agree with Red514's approach. You have to split your grayscale levels into 3 regions. 0-85, 86-170, 171-255. Then, re-spread each of those clamped regions back to the full 0-255 spectrum and halftone (convert grayscale to bitmap) each of those three into 3 screens. The 0-85 becomes your black halftone screen, the 86-171 becomes the mid-gray, and 171-255 becomes the light gray.

This will give you a truly broad spectrum grayscale.


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## skitten (Feb 16, 2014)

FullSpectrumSeps said:


> In relation to the splitting of a black gradient into multiple greys... this is better but obviously requires more screens than just 1... attached is an example of this where you have lots of soft shades of the greyscale, detail etc... and you want the high-end or best-quality way to produce it with the most consistency and smooth look to the shades... then you use automatic techniques to pull the perfect interlcoking diffusion or halftone blends with black and grey, black and 2 greys, or only using a dark, medium etc... Many different ways you can split it, but at the most I've never had to use more than 3 greys plus black and white for the highest-end-looking greyscale print. The cool part is you can tint the greys with any color you want on-press to get the sepia or other tonal looks, even using a bright ink to make it colored. But in reproducing an original black and white... the control over the print quality can still be maintained with good enough technique and equipment, however it will sure help if you can print with more screens then it will be easier to keep the tonal-shift under control from print to print.
> 
> For greyscale printing however, the correct method is always to interlock your halftones or diffusion patterns. If you take your greyscale separation curves, convert them to halftones all at the same angle, and then overprint them.. it will simply destroy all of the correct blending of the inks when you go to print and you'll see the angle of the dots much more, more chance for moire and a whole number of other issues.
> 
> ...


THANK YOU for the detailed info!! One more thing to add to my many stacks of notes. I see why people may have problems with half tones, lol. I had considered using half tones for a logo I am designing. I will definitely stick to line art for the time being until I have the extra money for additional supplies. And I guess it's time to consider buying Illustrator. Although there's many free programs out there i cant compare it to Ai.

thank you Deepbluex as well! I am planning to do several print tests once i get to that point. Do you guys find it pointless to print designs on paper to see how the details look or best to compare it on transparencies since it may or probably does print differently from paper? What looks great on screen may not be the case once the printer gets a hold of it.


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## speshoot (Apr 23, 2016)

AGR9 said:


> Just wanted to say thanks for all the help, it took a while to get round to even starting the project, but all worked out brilliantly with your tips.


i know this is an old post but do u remember your exposure time, light bulb, & emulsion? & thanx


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