Line screens for different mesh counts.

[inkbrigade]

I was working on some art and decided i should research my line screen settings.. Most of the info i could find online said 5X the line screen should be your mesh count.

Here is where i got the info from http://bit.ly/pBxeTT

Using that formula I come up with this for newman meshes.

S150 = 30lpi
166=33lpi
205=41lpi
272=54lpi

Does this sound right? For some reason it doesn't feel right. Thoughts?

[bimmridder]

I think if you're using "S" threads, you'll find you can using a higher LPI. The threads are smaller, so there will be less chance for mesh interference. I'll dig up a good formula for finding highest possible LPI. I think the formula you found is a "rule of thumb" kind of thing. If you start measuring thread diameter, open are, etc, you'll see you can do more than the "thread count times five " rule.

[mk162]

You can go as low as 4, I settle in at 4.5.

And it should be called "rule of wrist"

[bimmridder]

I stand corrected. Rule of wrist. And When in doubt, or just winging it, I did go by the 4.5.

[blue moon]

I can't remember where and who, but I think it was Murakami and there was a chart of the lpi's for each mesh. No time to dig for it now, sorry. . .

They actually tested each mesh and published the results. I remember them being somewhat odd as they gave different angles for some of the mesh counts (or something like that).

pierre

[blue moon]

I was working on some art and decided i should research my line screen settings.. Most of the info i could find online said 5X the line screen should be your mesh count.

Here is where i got the info from http://bit.ly/pBxeTT

Using that formula I come up with this for newman meshes.

S150 = 30lpi
166=33lpi
205=41lpi
272=54lpi

Does this sound right? For some reason it doesn't feel right. Thoughts?

and for what it's worth, we held a 3% dot on 330's at 58lpi for the award winning print. 1% and 2% were opening, but there was too much mesh interference. 3% was clean. This was the limit of the mesh and you really have to have all your ducks in the row to hit it. We spent few days dialing everything in to get there. Without the extraordinary measures, we are holding about a 4% dot with smaller dots not opening. I should also mention that at 60 lpi the results were not as good and from what I was told it is because the 330 is evenly divisible by 60 (well, it goes in 5.5 time which was hitting the knuckles of the mesh) and we were getting a lot of interference. Our choices were few lpi up or down and we chose 58 rather than 62.

We regularly use 55lpi on 225's (for underbase) with good results. Both 225 and 330 are S mesh.

pierre

[alan802]

I have a chart from Murakami that is on their July 2010 technical newsletter that gives all of the halftone angles for their smartmesh S thread to control moire.  Is that the chart y'all are talking about or is there something else out there I haven't seen?  I think there is some really good info about this subject in Saati's Handbooks as well.

[blue moon]

I have a chart from Murakami that is on their July 2010 technical newsletter that gives all of the halftone angles for their smartmesh S thread to control moire.  Is that the chart y'all are talking about or is there something else out there I haven't seen?  I think there is some really good info about this subject in Saati's Handbooks as well.

yup, I think that's the one. Can you post it here?

pierre

[jsheridan]

It's a PDF files.. saved it while back.

http://66.221.175.239/documents/HalftoneAnglestopreventmoire.pdf

[alan802]

Thanks John, that's the one I was thinking about.  I wish Murakami did more technical articles.  The few they do have are freaking gold.  I have them all printed out and in a notebook and I like to read them till I basically have them memorized.

[Dottonedan]

The general "rule's of thumb" all work (some more then others) but The "real" sure fire way to determine what mesh is best to maintain your full tonal range in all cases is print dots out from  (YOUR film), like as in a 1% fill in a 2"x2" square, then print it out in different line screens. I test them ALL within reason.

Example:
305 mesh, my test will consist of a 1% fill in a 45lpi, 46, 47, 48, 49, 50, 51, 52 etc. on up to 65lpi. You can go higher, is you feel you want to push the envelope by using 400 or 500 mesh with higher line counts.

If the goal is to really hold a full tonal range, from 1% on up, then you will be surprised at how low (your results) will be, Some might not want to know as you think you really hold much higher. Most will only be in the 45-48 line screen range on your mesh.  You really determine your (MAX) line screen by looking under a loupe and seeing what line screen will cover your specific mesh size opening (+ 1.5 threads)  As you would expect, it will be different for different types of printers, film types and mesh brands.

These squares are combined on one sheet. If your rip allows Photoshop to over ride the halftone settings of your rip, you can place them into a vector program and align them all up to be most efficient for your film format. If you can't do this, you will then need to cut them all apart and strip them together so that you only have one layer of film. Do not tape them over top of one large sheet as that doubles your film thickness and disrupts your exposure results.

Once you lay that sheet on your 300 mesh, burn the screen, wash out, then put ink through it, THAT result is where you do your readings. Not before. Way too much goes on before this stage to be able to get an accurate result. You will then see where you can hold what dot (at a maximum degree).

I think every shop should be doing this test over again every 3-6 months or at the least, once a year.  Your variables chance throughout the year/even season.

Some programs used to allow you to embed the multiple line count into a single grayscale file but I haven't been able to do that on the newer programs like I used to. Aldus Freehand allowed you to do this in your tool settings. Illustrator lets you chance the line screen (per very color). if you use Post Script and print through Illy's separation program. Now days, some common rips automatically override those setting from photoshop (even after I've chosen to have photoshop over ride the printers settings.

I have an Illustrator document (test sheet) I can upload...where you have all of these laid out, but you need a post script printer (to my knowledge). Most of the RIPS in Digital printers are the culprits that over ride the implanted halftone settings. If anyone wants to try the file and see if that can get it to print multiple halftones out using the film device of your choice, that would be great. Then post results.

Ok. Back to work.