S-mesh screen making issues

[Maff]

The quick question is this,

Do you change your screen making process with S-mesh screens, as apposed to how you would for regular t-mesh?? 
and do you find they are much more sensitive to all the different elements and conditions for proper screen making?

The longer story is this,
So, I had been using regular T-mesh for over 10 years with fine results. 
And then I started reading here about S-mesh/ thin thread mesh technology and how they could be an added benefit where t-mesh under performs.
I was excited to jump in and got my first round of Static S-mesh screens last year.

Right out of the gate we could not get them to expose properly.

My control is this.  Every time we make and process screens we are using both t-mesh and S-mesh at the same time. Same emulsion, coating, exposure, reclaim, dehaze... everything is the same for both. 

The main Problem I am having is getting a good deal of slime on the inside of the screen after exposing and washing out and sometimes we will also loose halftone details as well.  At first the Stauffer strip calculator would just totally blow out. We adjusted our exposure times quite a bit longer to the point where if we were careful enough we could get the image to expose, but still having slime on the inside and still not always getting our halftone details to stay.

My first though is that it seemed like the emulsion just wasn't grabbing this mesh.

I called Murakami, spoke with Al, went over all the basic stuff... everything should be the same.  He recommended we change the bulb in our Exposure unit... it was old, but our t-mesh screens expose fine... I changed it anyways just to cancel that out.  We have a 850W MH Nuarc exposure unit.
Called our supplier of the screens (spot color supply) to pick their brain and same responses... all should be the same.  They recommended Direct Prep-2... tried that with no noticeable difference.
(customer service was great from both BTW, very patient and took their time to go through it with me.

Tried changing emulsions, we use photopolymers, originally Chromaline WR... Switched over to Saati PHU and got the same results... (however, we really like this emulsion better with our regular t mesh and have been sticking with it)

We did have slightly better results with thinner coats of emulsion.  (I don't have an EOM gauge yet, but have been going off of trials and experience)

We have our coated screens in a decently well climate controlled environment with a thermometer and humidity gauge. We did notice slightly better exposure results when the screen booth temp is higher than 70 degrees and humidity % is in the 20s.

When we get the screens to expose good enough and get them out on press...  They have printed really awesome!!! and I really want to make them work in our shop dam it! we've been struggling with this for like 6 months now .

Also, if they get to press, the screens aren't breaking down, but we have been post exposing just to make sure and especially since we do a fair amount of waterbase and discharge printing

Jvanick just mentioned that he uses Direct Prep-1 on the first round in the shop.  We were told that it wasn't a good idea because it could harm the mesh... but honestly it kind of makes sense in the results I'm seeing, maybe it would give the mesh more grip on the emulsion...

Anyways, this is where I'm at.  Any other ideas would be greatly appreciated.
Thanks again everyone!!!!

[Shanarchy]

I'm a capillary film user and I have to hit them with a good scrubbing of mesh abrader. I hate doing it, but it's the only way I can make it work. After the first couple of rounds with a new screen they coat/expose like normal. It was pretty stressful for us as we swapped all of our screens over and couldn't get anyyhing to expose. I'm curious to see what others have to say. I just assumed it was because I'm the odd cap film user.

[Maff]

I'm a capillary film user and I have to hit them with a good scrubbing of mesh abrader. I hate doing it, but it's the only way I can make it work. After the first couple of rounds with a new screen they coat/expose like normal. It was pretty stressful for us as we swapped all of our screens over and couldn't get anyyhing to expose. I'm curious to see what others have to say. I just assumed it was because I'm the odd cap film user.

yeah that's actually what is making me go nuts here since we still have our t-mesh in the same rotation and they work fine... if I didn't have them, id really be going crazy...

[blue moon]

if you coat the T and S the same, S will have almost twice the thickness of the emulsion and you will have to increase your exposure times. Keep burning until there is no slime on the other side.

pierre

[GaryG]

Pierre is correct-

More open area allows more emulsion to flow out of trough with s-mesh.

I couldn't believe how the rz value changed with s-mesh too. Smooth as a baby's butt.

[mimosatexas]

yea I went from 2/1 with round side of an old coater on standard mesh to 1/1 sharp with monster max and s mesh.

[Maff]

if you coat the T and S the same, S will have almost twice the thickness of the emulsion and you will have to increase your exposure times. Keep burning until there is no slime on the other side.

pierre

Right.  Usually we would coat 1x1 with the round side.  We have been trying 1x1 sharp side on 150s with slightly better results but still getting some slime. 
But we did also try increasing our exposure, in our initially test we doubled our exposure times and still getting some slime.

Maybe the screens weren't dry enough? we try to give them a good day of dry time after coat. 

Although we have our screens in a decently controlled environment I've noticed they are still affected by our weather... if it's super hot and humid in the summer we were fighting to keep the humidity down in the screen booth and also since it's been a lot colder we recently bumped up the heat... There was another topic recently discussing the colder weather and exposure times.

It all made me wonder if the s-mesh are just more sensitive... or am I just realizing that screen making in general needs to be more precise and conscious part of the process... everything with our Tmesh was easy... rarely any issues.

[blue moon]

if you coat the T and S the same, S will have almost twice the thickness of the emulsion and you will have to increase your exposure times. Keep burning until there is no slime on the other side.

pierre

Right.  Usually we would coat 1x1 with the round side.  We have been trying 1x1 sharp side on 150s with slightly better results but still getting some slime. 
But we did also try increasing our exposure, in our initially test we doubled our exposure times and still getting some slime.

Maybe the screens weren't dry enough? we try to give them a good day of dry time after coat. 

Although we have our screens in a decently controlled environment I've noticed they are still affected by our weather... if it's super hot and humid in the summer we were fighting to keep the humidity down in the screen booth and also since it's been a lot colder we recently bumped up the heat... There was another topic recently discussing the colder weather and exposure times.

It all made me wonder if the s-mesh are just more sensitive... or am I just realizing that screen making in general needs to be more precise and conscious part of the process... everything with our Tmesh was easy... rarely any issues.

how long are your exposure times? I would expect a 3min +, possibly 5 with an 850W and 150S.

pierre

[jvanick]

When we switched from T to S mesh, we had all sorts of issues, and it took us a LONG time to get things sorted out.  At first we blamed the emulsion, and in a way it IS an emulsion issue, but more due to how the emulsion interacts with the mesh.

The intermediate story is long due to all of our testing... for that, I apologize.

To start the story:

when we switched to S-Mesh we started having edge breakdown and wear issues right out of the gate, sometimes even breaking down 5-10 shirts in to the run.  you could actually hear the screen 'crackling'...  We had changed to S-mesh in the winter, so the first thought was the SP1400 we were running was prone to issues in low humidity so Murakami had us try SP1400-W (a winter blend for SP1400)... the issues continued, not quite as bad, but still there, we started taping on the top of the screen well into the squeegee path... again, we'd still have issues (anybody who's met Tiffany know's that she's a tape nazi (no tape for you!) and she was complaining about all the tape... and heck sometimes the cracking would follow the tape into the rest of the image area, especially on long runs.

Somewhere around this time I started thinking that the Starlight didn't have the 'punch' to get through the screens successfully, this was totally incorrect, as the screens are being initially exposed correctly (solid 7 step), when we were having issues, we kept on adding time as well thinking more exposure would help (it didn't)

* we started playing with different types & brands of emulsions with differing results, but we still had wierd issues...

We did sun exposures with several different emulsions to prove out that the initial exposure wasn't the issue...

Then we switched over to Saati PHU-2, had the same issues, and started some major in-depth testing in the shop.

1. We got the exposure times dialed in better (they were concerned as we were over-exposing our screens, by 2 steps on the strip) -- better detail after that, but no better results on press.

2. We found that a 1/1 on the S-mesh (even 225S!) was resulting in 50% or more EOM.  We did a ton of testing here, until we finally found that 1 coat on the shirt side was all that was needed to achieve a repeatable 20%-ish EOM.  -- no better results on press.

3. We started post exposing... tried Starlight, saati 300W LED, and sun post exposure.  While the Saati 300W and Sun post exposure seems to result in better discharge/wb/hsa screens, for any plastisol work, there was no better results on press.

4. We started using Saati DirectPrep2 on our screens... no fish eyes, pinholes, water marks, anything after that, and the emulsion coats even smoother... but no better results on press.

*** It's important to note that through ALL of this, our older T-thread mesh screens were having NO issues.   This should have been a sign, but really with everything else going on, it didn't click.

FINALLY after at least a month of testing... Saati has us try Direct Prep 1 which is a light mesh abrader... at first I questioned this as "nobody needs mesh abraders anymore" seems to be the advice of everybody.

The first set of screens onto the press showed an immediate improvement, and since then, we've had no issues.

After talking with Saati, we think the issue is a emulsion adhesion to the smooth smesh, and with the fact that there's less thread diameter for the emulsion to 'grab' onto, we need to 'rough' the mesh up a touch with the abrader to get better mesh adhesion, and that was the issue...

[Maff]

if you coat the T and S the same, S will have almost twice the thickness of the emulsion and you will have to increase your exposure times. Keep burning until there is no slime on the other side.

pierre

Right.  Usually we would coat 1x1 with the round side.  We have been trying 1x1 sharp side on 150s with slightly better results but still getting some slime. 
But we did also try increasing our exposure, in our initially test we doubled our exposure times and still getting some slime.

Maybe the screens weren't dry enough? we try to give them a good day of dry time after coat. 

Although we have our screens in a decently controlled environment I've noticed they are still affected by our weather... if it's super hot and humid in the summer we were fighting to keep the humidity down in the screen booth and also since it's been a lot colder we recently bumped up the heat... There was another topic recently discussing the colder weather and exposure times.

It all made me wonder if the s-mesh are just more sensitive... or am I just realizing that screen making in general needs to be more precise and conscious part of the process... everything with our Tmesh was easy... rarely any issues.

how long are your exposure times? I would expect a 3min +, possibly 5 with an 850W and 150S.

pierre

Thanks everyone,

Piere,  No we're much less.  With PHU we've been under a minute... but our T-mesh hits a solid 7 on the Stauffer strip every time. 
Could the layer of emulsion be that much thicker on a S-Mesh?  twice as much?   Like 150s vs 156t for example...

Also, what do you think about abrading s-mesh... anybody else doing that? 

[Colin]

First:

What emulsion are you using.  And what exposure times do you have for your standard 150 mesh?

For my Nuarc 3140 1k Metal Halide bulb.  A 150/54 murakami mesh panel coated 1x2 with a monster max coater using Saati PHU with up to 30% EOM I expose for about 90 light units.  This gives me a solid step 7 with a stoufer strip.  It also holds awesome detail.

For a 150 S mesh from Murakami I need to expose for about 130 light units.  My eom is around 50%.  This gives me a relatively solid step 7 on the stoufer strip.  I do need to be more careful with thin lines and finer detail than I do with standard mesh.  This is simply due to the lower thread area/solid area for the emulsion to grab onto.

Note on emulsion hardness: 

The FIRMER an emulsion is, the more you will see these finer areas hold its image shape.  Simply because the emulsion is more rigid.

The SOFTER an emulsion is, the more these fine areas will wash away even with proper exposure/over exposure


***BIG NOTE FOR ALL THIN THREAD MESHES****


Because you have less surface area/thread area for the emulsion to grab onto, it is easier for the emulsion to release on the stoufer strip.  Thereby giving you an inaccurate reading about "full" exposure.  You can easily end up with a solid step 5 or 6 when it should be 7.

A lot of this is determined by how long the screen HAS BEEN ABSORBING/SOAKING up water.  The more chance it has to soak up water, the easier it is to release.


These observations are what happens in my shop, with my equipment.  Your mileage may vary

As for direct prep:

It abraids the mesh making for better mechanical abrasion.

The reason why you see cracking on water resistant emulsions is do to the emulsion DELAMINATING from the mesh under high pressure.

Because of the better mechanical adhesion you see less delamination of the emulsion.

Delamination/cracking typically happens with very dry screens and occasionally screens with a thicker emulsion coat but I don't know the nuances of why.... There are apparently other reasons as well, which I also am not currently aware of.

[Frog]

Also, what do you think about abrading s-mesh... anybody else doing that?

According to some here, as Martha Stewart may say, "it's a good thing", but I cringe a little.
The knock on physically abrading mesh to increase "tooth" is that it weakens the mesh. The biggest caution on S mesh is that it's more fragile to begin with.

In general, most have gotten away from abraders with emulsion due to it's characteristic of encapsulating the mesh, but may still use it with capillary film (and older direct and indirect stencil films) which does not tend to do the same.

I am really curious about this.
Let's see how mesh lifespan is affected, if at all.

[Maff]

When we switched from T to S mesh, we had all sorts of issues, and it took us a LONG time to get things sorted out.  At first we blamed the emulsion, and in a way it IS an emulsion issue, but more due to how the emulsion interacts with the mesh.

The intermediate story is long due to all of our testing... for that, I apologize.

To start the story:

when we switched to S-Mesh we started having edge breakdown and wear issues right out of the gate, sometimes even breaking down 5-10 shirts in to the run.  you could actually hear the screen 'crackling'...  We had changed to S-mesh in the winter, so the first thought was the SP1400 we were running was prone to issues in low humidity so Murakami had us try SP1400-W (a winter blend for SP1400)... the issues continued, not quite as bad, but still there, we started taping on the top of the screen well into the squeegee path... again, we'd still have issues (anybody who's met Tiffany know's that she's a tape nazi (no tape for you!) and she was complaining about all the tape... and heck sometimes the cracking would follow the tape into the rest of the image area, especially on long runs.

Somewhere around this time I started thinking that the Starlight didn't have the 'punch' to get through the screens successfully, this was totally incorrect, as the screens are being initially exposed correctly (solid 7 step), when we were having issues, we kept on adding time as well thinking more exposure would help (it didn't)

* we started playing with different types & brands of emulsions with differing results, but we still had wierd issues...

We did sun exposures with several different emulsions to prove out that the initial exposure wasn't the issue...

Then we switched over to Saati PHU-2, had the same issues, and started some major in-depth testing in the shop.

1. We got the exposure times dialed in better (they were concerned as we were over-exposing our screens, by 2 steps on the strip) -- better detail after that, but no better results on press.

2. We found that a 1/1 on the S-mesh (even 225S!) was resulting in 50% or more EOM.  We did a ton of testing here, until we finally found that 1 coat on the shirt side was all that was needed to achieve a repeatable 20%-ish EOM.  -- no better results on press.

3. We started post exposing... tried Starlight, saati 300W LED, and sun post exposure.  While the Saati 300W and Sun post exposure seems to result in better discharge/wb/hsa screens, for any plastisol work, there was no better results on press.

4. We started using Saati DirectPrep2 on our screens... no fish eyes, pinholes, water marks, anything after that, and the emulsion coats even smoother... but no better results on press.

*** It's important to note that through ALL of this, our older T-thread mesh screens were having NO issues.   This should have been a sign, but really with everything else going on, it didn't click.

FINALLY after at least a month of testing... Saati has us try Direct Prep 1 which is a light mesh abrader... at first I questioned this as "nobody needs mesh abraders anymore" seems to be the advice of everybody.

The first set of screens onto the press showed an immediate improvement, and since then, we've had no issues.

After talking with Saati, we think the issue is a emulsion adhesion to the smooth smesh, and with the fact that there's less thread diameter for the emulsion to 'grab' onto, we need to 'rough' the mesh up a touch with the abrader to get better mesh adhesion, and that was the issue...

Thanks Jvanik!  Wow You went through it hard! 
Your situation is sounding very similar to mine.
So did you only use the Direct Prep-1, one time or multiple times per screen?

I think I'll give the direct prep-1 a try.  It makes sense to me... but its strange that no one else has made much mention... maybe there is another way around it?

And I'm also going to need to do more testing with exposure time and EOM and keep close track of my results... at the end i'll at the very least have a much better understanding of the finest details.
Now I just need to get myself an EOM gauge... any suggestions?

Thanks everyone!!!

[jvanick]

Just once at the beginning of new mesh seems to be all it takes

[Maff]

What emulsion are you using.  And what exposure times do you have for your standard 150 mesh?

Saati PHU and we are under a minute... but our stauffer strip reads 7 on T-mesh and always has... but this is way off compared to what everyone else here is saying, so maybe i need to adjust this.

***BIG NOTE FOR ALL THIN THREAD MESHES****

Because you have less surface area/thread area for the emulsion to grab onto, it is easier for the emulsion to release on the stoufer strip.  Thereby giving you an inaccurate reading about "full" exposure.  You can easily end up with a solid step 5 or 6 when it should be 7.

A lot of this is determined by how long the screen HAS BEEN ABSORBING/SOAKING up water.  The more chance it has to soak up water, the easier it is to release.

Yeah I found it very strange how the stuaffer strip acts so differently with the S-Mesh

so after exposure, how long do you keep it in the developing tank before rinsing out? 

Typically ours sit in the water for about 1-2 min

thanks again!!