halftone problems/accurip question

[Shanarchy]

I very rarely do anything with halftones. I've been able to do them in the past but am really being challenged with this job.

I use accurip. My first question, is there recommended settings I should have this at? Epso 1400 printer, MSP3140 exposure unit.

The film looks like it makes sense as far as the halftones go, but I honestly have no idea. I also seem to be washing out some of the larger halftones and losing the finer ones. I'm completely lost and the customer needs these asap.

Thoughts? Suggestions? I really don't think this should be that difficult for me, yet it is starting to seem impossible.

[Dottonedan]

It doesn't sound like an accurip question, but rather an exposure and/or halftone to mesh selection question.

Losing dots mostly means two things,
1, you might be under exposing the screen. This can happen randomly if you've avoided doing a more accurate exposure test for your regular bold/solid type of art. It's easier to use an under exposed screen and not realize it.  As you get down to using halftones, an under exposed screen doesn't hold those smaller dots or even very fine line work. You may need to go the full Monty and really narrow down a proper exposure time (that includes) holding fine halftones.

2, if you know your exposure times are as good as they can be, you then want to look at the mesh (count) and confirm that it's a mesh that does work with the halftone line count that works best.

Most use the rule if thumb of mesh count divided by 4 or 4.5.
I like to use 5 on higher mesh as that will help you assure yourself you are giving yourself every oppertunity to hold even the tiniest of dots (on the given mesh).

200 mesh decided by 4 equals 50 line screen,
200 mesh decided by 4.5 equals 44.4 line screen, (rounded to 45)
200 mesh decided by 5 equals 40 line screen,

Being that I don't like to go below 45lpi for sim process,
I may stick with 4.5 on that 200 mesh.

Lower mesh than that, I'm ok with using lower line counts.

[Shanarchy]

Thanks for the reply Dan.

I thought I had my exposure times dialed in. But you are absolutely right, when small text is as detailed as you get you can really be off and never know it. That is what I'm thinking may be a big part of my issue. But I do find it a little odd that I'm losing/washing out halftones on the bottom (where it is almost solid) which would seem like under exposure and losing halftones/can not wash them out at the top (very fine halftones) which would seem like over exposure.

I know it is a me issue. Accurip is good software (for my usages) and the MSP3140 exposure unit has a new bulb and is a great unit.

It's just tough because I really want to trouble shoot and figure this out, I should be able to do stuff like this without any thought, but also have to deliver the job in the AM. (last minute job from a really good customer).

So I am using 200 mesh and settings were:
printer resolutuons: 60 lpi/300dpi
which sets document ink options to:
frequency: 60lpi angle: 45 degrees, dot shape: dot

I can change it to 53lpi/300dpi
which will change the document ink options to:
frequency: 53lpi angle: 45 degrees, dot shape: dot

I can probably change these options further I'm guessing. So if I'm understanding correctly I should try to change this to 40lpi?

[Dottonedan]

Yes, drop to 45 at most on the 200 mesh to hold those 3-5% dots.
60 is just too fine of a dot for the mesh threads on a 200.

An accurate way of telling for sure is to lay the film on an uncleared mesh. Look at the areas where you were losing dots, usually the ends of fades). Your smallest dot should overlap a mesh opening and (two) mesh threads. Wen looking at it this say, you can clearly see that your vhoice if line screen is just too fine. Most If not all if maybe the 8-1% will be blocked out by the mesh threads. The option is to go to a lower line screen that makes for a bigger dot, or, to go up on your mesh so that you are using thinner threads.

[Croft]

when in accurip settings under LPI , set to your desired screen 45lpi , 50lpi etc. Make sure to check the "lock screen"s button . If you don't it will print film in your programs default Illustrators is 60 lip. I pulled my hair out trying to shoot 60LPI screens in the beginning .

[IntegrityShirts]

Also if you're printing with 200 mesh, refer to this PDF for the correct angle for your halftone dots. 200 has a much narrower window for preventing moire. I just wish they had the angles listed for 50lpi, but it's just 45 and 55 in this chart.

http://murakamiscreen.com/wp-content/uploads/2012/07/HalftoneAnglestopreventmoire.pdf

[IntegrityShirts]

Also make sure the print quality setting is maxed out. The dots look horrible under a loupe on anything other than maximum resolution.

[jvanick]

... and do your ink density tests again if you change to a higher resolution... using all 6 cartridges on Fixxons film at the highest res, even on a ink droplet size of 6 was enough to have WAY too much ink on the film and cause issues.

somebody here said that using 1 cartridge at high res was the way to go for the best dots... so maybe try to start there

[Shanarchy]

Awesome info here guys!

It seems like my biggest problem was the 60lpi. I'm going to keep playing around with this further. I want to make sure I have this stuff really dialed in going forward.

This place is seriously the best!

[Sbrem]

A lot of here will tell you that you get better resolution with one head for halftones. Also, once set up in AccuRIP, you can make your line count, angle and dot shape from within the Illustrator, click on Output, choose the colors you want to print, and set those parameters.

Steve

[Dottonedan]

Also if you're printing with 200 mesh, refer to this PDF for the correct angle for your halftone dots. 200 has a much narrower window for preventing moire. I just wish they had the angles listed for 50lpi, but it's just 45 and 55 in this chart.

http://murakamiscreen.com/wp-content/uploads/2012/07/HalftoneAnglestopreventmoire.pdf

Thats good for the Murakami mesh, but not any other mesh. I didn't see that he mentioned using the Murakami mesh.  It's good to pass around the info on that tho.

[Shanarchy]

Nope, regular mesh here still. We've used a couple of the S-mesh panels and I tore a couple stretching and my screen guy blew out a couple in reclaim. We both need to learn to be a little more careful before I can make the switch.

[IntegrityShirts]

Also if you're printing with 200 mesh, refer to this PDF for the correct angle for your halftone dots. 200 has a much narrower window for preventing moire. I just wish they had the angles listed for 50lpi, but it's just 45 and 55 in this chart.

http://murakamiscreen.com/wp-content/uploads/2012/07/HalftoneAnglestopreventmoire.pdf

Ahh see what happens when I assume!




Thats good for the Murakami mesh, but not any other mesh. I didn't see that he mentioned using the Murakami mesh.  It's good to pass around the info on that tho.