# Half Tone Dot Gain



## scrible1980 (Feb 21, 2008)

Hello,
I would like to know if anybody can give me some advice on half tone screenprinting and dot gain. I have not printed any half tone images yet, but would like any tips or recommendations if anybody has any. Many thanks.


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## Challenger (Nov 30, 2007)

In order to compensate for dot gain, it's common for t-shirt printers to minimize the dots in the 5% highlight area and in the 95% area.
In the highlight area the 5% dot can gain and become 10% to 15% or more if too much squeegee pressure or too coarse of a mesh is used. The shadow dots in the 95% will gain and become a solid, therefore, it is common to output your halftone films with a tight tonal range of 10% to 90%, this means there will be no dots below 10% and every dot above 90% will be solid black.
Please be aware that printing in a manual press will require more compensation than printing in an automatic press.
Hope this can help you.
Challenger


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## macmiller (Jul 23, 2007)

Fred,
How'd you make the art for the graduated screen? I was thinking of making one with different lpi's on the same positive so i could see how fine of dot i could get on a variety of meshes.

tia!


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## ScreenPrintMan (Jun 1, 2008)

You'll also want to watch out for moire pattern distortions caused by your mesh count and the size of your dot pitch.


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## kimkimkim13 (Aug 20, 2009)

how do you avoid the moire pattern? is there a formula?
thanks.


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## PositiveDave (Dec 1, 2008)

Trial and error.


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## jsf (Aug 4, 2009)

scrible1980 said:


> Hello,
> I would like to know if anybody can give me some advice on half tone screenprinting and dot gain. I have not printed any half tone images yet, but would like any tips or recommendations if anybody has any. Many thanks.


Here's an article you can easily understand about Half-tones.

Hope it helps.

IMAGES - THE JOURNAL FOR TEXTILE SCREENPRINTING ,EMBROIDERY, PROMOTIONAL CLOTHING AND GARMENT DECORATION


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## essen48183 (Sep 25, 2009)

And this should help people with dot gain. I am tackling this now. This looks like the perfect info. Managing Textile Dot Gain | ScreenWeb | screenweb.com


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## PositiveDave (Dec 1, 2008)

I print out a calibration strip and measure the print result on the finished item. It's usual to have to lighten the shadow area and boost the highlights - highlights tend to fill-in (they are small holes in the emulsion, we're talking negatives here) and shadows, because they are small dots fall off the mesh when they get too small.


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## sister1 (Jun 16, 2008)

Need help! I am printing a job I did originally last year -- same positives I used before. The image has a large area shaped like a flame, and I did the seps on 2 pages, with one being an orange fade that decreases in intensity at the top, and the other a yellow fade that decreases in intensity at the bottom. When I printed this before, the colors muddled together in the middle and gave a nice fade from solid orange at the bottom to solid yellow at the top, which was the intention. 

I reburned screens (280 mesh count), and did a perfect registration alignment, and when I print it, I am getting a moire pattern where the halftones overlap-- a first for me. I've tried moving it very slightly out of registration; using a higher off-contact (first for one screen only, then for both) thinking that if I moved the dots on one screen slightly off, the color might mingle. I've printed wet-on-wet and also tried flashing between colors.

The positives were printed through Corel Draw, using FastRip, with a frequency setting of 45 and angle of 25, as recommended by Fresner. The settings on the fountain fills in Corel are:

white to yellow:
angle - 90
edge pad -7%
midpoint - 25

orange to white:
angle 90
edge pad - 21%
midpoint - 60

What should I be looking at to correct this? Do I need to reprint the positives with different settings? Reburn at least one of the screens with a different mesh count? Any suggestions will be appreciated.


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## essen48183 (Sep 25, 2009)

try 22.5 degrees and 55. (I use that on ALL the screens in the separation, as recommended by accurip, and it works just fine) I use 280 screens same as you. 

If those settings worked before for you, though, I might suspect a loose screen.


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## Biolek (Jan 6, 2010)

essen48183 said:


> try 22.5 degrees and 55. (I use that on ALL the screens in the separation, as recommended by accurip, and it works just fine) I use 280 screens same as you.
> 
> If those settings worked before for you, though, I might suspect a loose screen.



And how will look like the print using 230 mesh?


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## PositiveDave (Dec 1, 2008)

90 is not a good angle for screenprint. If your mesh is square with the frame, rather than being rotated, this can generate moire.
Changing the angles can cure it, as can changing the mesh count.


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