# Which screen mesh to use with halftones



## tturner45 (Sep 6, 2010)

OK, I need for someone to tell me hoe to figure out what is the lowest screen mesh count I can use to print half tones. I recieve my designs by way of a PDF from my designer, I also have rip software! Once I recieve the pdf file can I set the lpi in the rip to what I want or what! PLease help!

Thanks


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## red514 (Jul 21, 2009)

if i recall correctly the math is, multiply your LPI by 5 to determine mesh count, always round up the mesh count, lower is not recommended.
45lpi x 5 = 225 so you would use a 230 or higher
55lpi x 5 = 275 so you would use a 280 or higher


some one correct me if i'm wrong, please


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## tturner45 (Sep 6, 2010)

OK next question...what line count do I set the rip for on halftones


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## red514 (Jul 21, 2009)

what mesh count will be used?
i'd recommend 45lpi for beginners, easier to expose and print but dot gain is often an issue. 55lpi is very common and some skilled shops with good equipment will go as high as 65lpi.


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## tturner45 (Sep 6, 2010)

OK thanks for the help! So I can set the lpi in my rip software @ 45 and be good!?


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## red514 (Jul 21, 2009)

also set the angle to avoid moire as much as possible, the most common angle used for this is 22.5 degrees


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## PositiveDave (Dec 1, 2008)

You will get more dot gain at 65lpi than 45lpi, there's a lot more edge to the dots per unit area. Dot gain happens at the edge.


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## red514 (Jul 21, 2009)

PositiveDave said:


> You will get more dot gain at 65lpi than 45lpi, there's a lot more edge to the dots per unit area. Dot gain happens at the edge.


hmmmm... hadn't thought of that and it does make sense. however, to expose a 65lpi halftone dot pattern requires 300+ mesh counts, using those high mesh counts helps to control ink deposit reducing dot gain. I have no first hand experience exposing or printing 65lpi halftones, so my comments are just theory.


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## tturner45 (Sep 6, 2010)

OK a little confused..lol are you talking about setting the angle in Ai or in my rip software? I don't have AI or any graphic design program ! I have printed halftones positives before with my rip software, but what I was wanting to know.........lowest screen mesh to use...ya'll got me straight on that one...BUT do I set the lpi in the rip before I print the positive?


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## The Professor (Jan 2, 2010)

tturner45 said:


> ...do I set the lpi in the rip before I print the positive?


That is correct.


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## red514 (Jul 21, 2009)

tturner45 said:


> I don't have AI or any graphic design program !


if you are interested, there's a freeware vector program called Inkscape Inkscape. Draw Freely.
it's not as intuitive as AI (and AI isn't all that intuitive either lol)

and if you're not using Adobe Photoshop or another bitmap editor you can try this other freeware bitmap program called Gimp GIMP - The GNU Image Manipulation Program


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## bluemoon (Feb 8, 2009)

tturner45 said:


> OK, I need for someone to tell me hoe to figure out what is the lowest screen mesh count I can use to print half tones. I recieve my designs by way of a PDF from my designer, I also have rip software! Once I recieve the pdf file can I set the lpi in the rip to what I want or what! PLease help!
> 
> Thanks


which RIP are you using?
Most RIPs you should be able to lock your lpi and angle in the the software. GhostScript is an exception.
If you don't do this often, 45 lpi on 230's is a good start. 
Make sure you have your emulsion timing dialed in. I have never tried to do the halftones with anything but metal halide, but am being told it does not work very well.
Which emulsion type are you using? SBQ/photo polymer or dual cure? Dual cure is more forgiving on the time, so it might make sense to try it first. 


pierre


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## tpitman (Jul 30, 2007)

I've done halftones on a multi-tube unit I built with a vacuum blanket, but they won't be as sharp as on a single-point unit with vacuum.
Also, you can get more detail, along with the wider exposure latitude, by using a dual-cure emulsion as opposed to an SBQ.


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## IprintedMondo (Sep 4, 2015)

IM looking forward to printing a halftone but Im not sure how to make it happen. I can send email of the picture and somebody could help and guide me? That would be awesome! thanks!


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## IprintedMondo (Sep 4, 2015)

What is Lpi? Im using adobe photoshop cc


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## TyMeier (Aug 31, 2009)

If you want to go deep into the rabbit hole, explore, in psd, the 'Bitmap' function under Mode, like this:

Set your artwork up in channels 

Copy paste each channel into a new greyscale document.

Go to Image, mode 'Bitmap' and on the dropdown menu choose 'halftone screen'. and hit ok

In the next pallet set your lpi and angle, and in the dropdown menu choose 'Ellipse"

That will change your image into halftones.

Copy paste that back into the channel of your first document (going over the original artwork, so save, or duplicate the channel)

Line up the channels and you can see how the halftones interact.

If you want to print from there the doc needs to be like 900 ppi (a Raster Image Processor prints at 1200 ppi or 2400 ppi). But AccuRIP also lays down more ink on the film, so you miss that by doing it this way.

It'll teach you a LOT I promise.


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## chuckh (Mar 22, 2008)

If you are not doing photo reproduction and are unfamiliar with halftones, 35 lpi works very well - easier to expose and print. Good starting point.


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## rutler (Jun 25, 2013)

We use 55 lpi with an angle of 22.5 and an elliptical dot for almost every halftone screen, including simulated process. We almost never have Moiré or missing information. However, we do have an I-Image and it's resolution is great.


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## sixo (Aug 31, 2015)

please i dont even know what a rip software is can someone be kind enough to bring me up to speed


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