High EOM Screens (not HD) or Standard EOM for Spot Color Plastisol

[ZooCity]

Who uses high EOM stencils for their regular plastisol prints and who uses "standard" EOM stencils?   What meshes do you run and if you use high OEM where do you use high EOM, i.e. just on the UB or on hilite colors as well?

Rather than sharing EOM readings, let's define "high" EOM as having a distinct, relatively high sidewall when felt on the finger tip and being a coating that is beyond the necessary minimum thickness for the mesh. 

We have one screen that we optionally run at higher EOM here, 150S. 

I like a higher EOM stencil on this mesh for plastisol UBs and then 225S for the hilite colors, in general. 

My staff is asking to drop the high EOM version of this screen and instead run all 150S screens with lower EOM v. the aforementioned combination.  I'm on board with this since it drops an emulsion, a coating type a press setup approach and ultimately a screen type from our roster.  Simple is always better. We are testing it now.

Issues so far have been related to moire that develops in the ink film when using two of the same screen with plastisol.  This issue has me leaning toward reinstating high EOM UBs so we can use a different mesh up top.  We have a simplified mesh selection and I don't want to add other mesh counts.

[Frog]

Who uses high EOM stencils for their regular plastisol prints and who uses "standard" EOM stencils?   What meshes do you run and if you use high OEM where do you use high EOM, i.e. just on the UB or on hilite colors as well?

Rather than sharing EOM readings, let's define "high" EOM as having a distinct, relatively high sidewall when felt on the finger tip and being a coating that is beyond the necessary minimum thickness for the mesh. 

We have one screen that we optionally run at higher EOM here, 150S. 

I like a higher EOM stencil on this mesh for plastisol UBs and then 225S for the hilite colors, in general. 

My staff is asking to drop the high EOM version of this screen and instead run all 150S screens with lower EOM v. the aforementioned combination.  I'm on board with this since it drops an emulsion, a coating type a press setup approach and ultimately a screen type from our roster.  Simple is always better. We are testing it now.

Issues so far have been related to moire that develops in the ink film when using two of the same screen with plastisol.  This issue has me leaning toward reinstating high EOM UBs so we can use a different mesh up top.  We have a simplified mesh selection and I don't want to add other mesh counts.

I'm still trying to wrap my head around what you consider high.  The glisten method of coating generally produces an EOM of 10% - 20%.
I can feel the edge of the sidewall with my fingernail) Since learning the purpose of EOM to eliminate any effect like sawtoothing from the mesh and produce a good seal for the ink, this is now my normal EOM, and not considered high.

[Colin]

The first time I actually measured my eom on a 150s...... it was close to 100%..... gasp right?  Realllly easy to do without thinking on S mesh.

We loved the brightness of it and we had no problem printing and flashing it.  Smoothing screen was great etc...

Over the next couple years, white ink rheology changed and it also got a little tackier after the flash.  I started to thin out my stencil so it was about 50% eom.  White bases flashed better etc, we still loved the brightness, but we worked a little harder for it.  Yes, we were very picky...

I have seen some pattern interference when using a 150s mesh screen for color over a 150s base white, but mostly with the more translucent colors, and even then, mostly when you are trying to print a touch thinner ink deposit.  Thicker ink deposits are not as noticeable.  I still highly prefer the 180s mesh for top - spot - colors with 225's being used when needing to print wet on wet.

Hope this input helped Chris!

[Atownsend]

I find it really hard to get EOM much lower than 100% on 150/48 or 135/55. If you're already coating 1/1 sharp at a pretty fast rate, is the only recourse to switch to a lower solids emulsion? What is your technique to get that down? I don't remember the figure last time I measured it, but it was also waaaay high on our 230/40's & 280/34's (NBC). But we dont do tons of halftone work so it hasn't been an issue there other than excessive / unnecessary emulsion usage.

We use 135/55 & 150/48's which are definitely high EOM. Tops are 230/40 about 95% of the time. 280/34s for halftones but that is a rare day. No intermediate mesh count like the 180. The 135/55 & 230/40 have been really good to us in terms of durability. 230/40 has roughly the same specs as the 225S from murikami.... but those 5 extra threads save a lot of popping in my experience.

The pattern interference what the hell is that?? I saw that that pop up a few times last year. Never found a real solution. Specifically red (rutland) 150/48 on a base white 150/48. Could never figure that out, but the issue went away when we moved to 230/40s for the top colors. It was mind boggling when I first saw it as I had never seen moire anywhere other than in halftones. I don't have a solution or that, but I should mention that I only ever say it when we printed red inks. No issues with yellows / golds / blues that I recall.

[Colin]

Atownsend - I have used both Saati PHU (45% solids) and Murakami T9 with diazo (44% before diazo) on my thin thread mesh.

I found that, with using a monster max scoop coater, I needed to find my sweet spot by pulling back just a little on my angle/contact with the top of the scoop coater and really pay attention to my coating speed.  Fast was not always better.

Even then getting below 40% eom is difficult.

If you want to see an example of pattern interference/thread interference patterns do this:

Print out a 50% halftone in a 4x4 box.  Do 2 films, one at 40 lpi and another at 50 lpi.  Stack them.  You will see some dots falling right on top of others and then slowly, you see them fall off of the rest of the dots until they line up again.  This isnt *exactly* whats going on when you overprint with the same mesh count, but it gives you an idea of whats going on.

[Maff]

I'd say we are running a normal EOM. Its been a while since I got the gauge out and measured them. But we coat our sMesh 0/1 with the round side.  We often print 150s base white and 225s top colors. But I also really like 135s when the design is a good match, the ink just drops through the mesh so nice. Sometimes we use 230t for top colors also.
Yeah we have had the weird pattern when printing 150 base and 150 top, so i try to avoid that, I'll stick a 180s in there instead for those situations.
We try to keep our prints thin, we like the feel, but also we have a small press so controlling the heat is a concern.

[Stinkhorn Press]

theoretically - mesh thickness controls your deposit, not EOM, no? excepting the very short space from the edge of your "gasket" the squeegee is pushing the mesh to the shirt - the EOM doesn't have anything to do WITH your deposit thickness (unless you are only printing small areas). no?

[ZooCity]

Frog I would consider "high" any eom above an beyond what most shops would call "standard" using a glisten method, etc.  So think of your regular stencil x1.5 or 2 maybe on the shirt side.  I find it hard to swap notes on EOM for some reason.

Colin, thanks that helps a bit.  I also loved the 180S for plastisol spot top colors, it's the ideal one but we've been progressively simplifying everything here and are now down to 4 regular mesh counts.  I'd hate to add one back in.

Which brings me to Stinkhorn's question and the answer is both.  Take a 180S and 225S for comparison attached.  These two are close in open area but the higher mesh thickness of the 180 adds to the theoretical ink volume.  Joe Clark would probably agree with you that mesh thickness should be considered for let down before EOM.   I've found that if you can "fill" the cells of a higher EOM stencil and successfully pump the ink through it without getting print issue you will get more ink down on the top of the fibers.  In our shop we sacrificed the superior 180 for plastisol printing in the name of knocking out a mesh count and effectively upping our screen library without adding screens.  150 or 225 is used in it's place for hilite colors.   

Which leads to the moire issue and it seems to only happen on two of the same mesh and is only noticeable on spot fill area.  And yes, far more pronounced on the translucent colors but still there if you look on most.

I think I know somewhere in my head that you don't need the extra EOM and blade choice/speed/angle/ink rheology are what should be the determining factors for opacity but the high EOM stencils just work best in some cases so it might be hard letting go.