Moire on 100% solid areas - Randomly

[Dottonedan]

I'm currently baffled by some mesh issues myself. I keep getting moire (in the mesh) and coating has been as always, great.  So I did a halftone test. Printed various % boxes  at 55lpi and at 65lpi )on both 230 mesh and 305 mesh).
Each group of boxes were output at different screen angles. I'd get moire in several boxes each each screen angle. Some had moite all across the row of boxes. Some had jsut 2 or 4 boxes with moire.    Frustrating.  I keep going back to (the mesh is stretched distorted).  I first thought it was random but it's more like 75% of the screens we have.  But the same test on another screen....and the moire is on other boxes. Worse in some degrees and less in others...then skip to the next degree of angle and it's totally different.

[shurloc]

Let me guess.  Static frames or panel lock mesh.  Both that are factory stretched. Doesn't matter who you get them from, they all provide poor stretching alignment.  They just do it too fast and don't pay close attention like you would if stretching in your own shop. Typically, you don't see this in the print on solid art (unless, it's drastic or large) rainbow like arches that can be noticed more easily.  Small or tiny bands get buried and I think he stretching shops gear their quality for this type of work where it just gets hidden.

I'm going to assume that a "panel lock mesh" is something different than we offer, but if you meant our panels, you are 100% incorrect. We are actually able to hold the manufacturer's tolerances on the mesh panels that we make down to about 2% off at 90°. We begin our process by using a straight thread line (not the area of least resistance like stretching a static frame, roller frame or any other manual stretching technique) and produce our shapes using a 4 point registration system with a very repeatable process. From there, we are able to monitor how skewed the mesh is on a panel by panel basis and have a .25" tolerance at 10 feet of material. If it is outside that skew, the mesh is rejected and returned to the manufacturer. Since the panels are setup at "square" and the base connectors are attached at that point, we have almost no possible way that the mesh doesn't stay square through out the entire stretching process.

I've said this for a long time.  The rush process of the stretching supplied mesh on panel frames or Static frames are rushed too fast. They don't have "perfect thread alignment" in mind for this type of supplier.  Thats my hunch.

You're thoughts here are dead on. We call it shock tensioning vs. stage tensioning here, but you are correct. Static frames are always made using shock tensioning. This process pulls the mesh out as quickly as possible, "shocking" the stretch out of the threads. Some mesh reacts fine to this treatment, while others will skew badly. Depending on the manufacturer's recommended treatment of their mesh, we design the fabric to work the best way possible. For the most part, we recommend the stage tensioning method, as you can see by the way our stretching systems work vs. other manufacturer's systems. Our Accelerator for Roller Frames has you load the mesh under light tension (stage 1) before rotating the frame the first time (stage 2) then bringing the mesh "up to tension" (stage 3) and then finally locking the bolts (stage 4.) Our EZ System works the same way with bringing all the panels from loading (stage 1) to all on hook 2 (stage 2) to finally fully stretched on hook 3 (stage 3.) We've seen it all from manufacturer's making claims that shock tensioning can work, but there's nothing better than giving that screen 10-15 minutes to settle during the process - regardless of what system, frame or mesh you are using.

We are still getting random moire issues.  I've put tape on the side of the ones that I've gotten moire or more like (mesh interference) from so I can be sure to confirm that my problem is the mesh.

We coat the same, expose the same and I still get moire "randomly".   Like 2 out of 7 frames will have moire if using any halftones.  and it's not my angle (22.5).  70% of the screens provide great halftones at the same lip and same screen angle....while some don't.  I've tried different angles (and get the same results). I've tried lowering LPI...and go through 3 screens to get one good one without moire.  It's MESH alignment.

You may be on to way more than you think here. We have had some manufacturers deliver mesh that was quite a ways out of square. Typically, manufacturers allow for up to 2° of "miss" before they call the mesh out of spec. This means that mesh could be more than an inch off of square at 1 yard to be within that spec. When you are talking exact tolerances with your 22.5° artwork and then the mesh skews back 4° at the top and -2° at the bottom, you'll almost never be able to hit that number exactly. Then, the next frame is .5° at the top and -.5° at the bottom and your net 21.5° art looks just fine. It's definitely a moving target and something we have to watch extremely carefully when we are producing our panels.


To sum this up, our panels are designed to be as square as the mesh has been manufactured. We have the added bonus of being able to screen the mesh before it's stretched and see how far "off" it is before it's turned into a panel for a screen. I have a feeling most shops stretching frames from bolt mesh have never checked their rolls to see how straight the mesh was woven. Dan, you're really nailing a huge thing here in mesh consistency, and the importance of it. This is also why it's so important not to over tension the mesh or apply too much squeegee pressure to clear it. All of the added factors can lead to distorting thread lines and lead to a ton of issues down the road.

Anyways, just dropping my 2 cents on this one and making sure that we weren't being lumped into that "inaccurate mesh" category because we can virtually guarantee that we have the straightest mesh available for virtually any frame out there.

- Ron

[Dottonedan]

Ron,


I re-organized your quotes for more clarity in the post. It was for the most part all in one quote as if I wrote it.
[ quote ] to begin a quote in a new paragraph.   [ /quote ] to close off the quote of a paragraph.

I very much appreciate the education there in your post and I don’t mind at all, being corrected. I now know more.
90% of my experience with this issues (and currently), has been on static frames from several different suppliers.   I will say, at the last shop I worked at, we used Shurloc panels.

I’m convinced your Co goes farther than other methods to assure consistency. Having said that, there have been times (at my previous place of employment) when I’ve come across the tops of panel frame stretched mesh that arched at the tops and bottom within the print location (the sweet spot). This would only be noticeable in the 5% dots of a 55lpi on a 305 mesh.  Usually the most noticeable on high mesh, with 55-65lpi, and in the 5% range of tone. The results were to get a moire or distorted rainbow pattern in those 5% areas or near that %.

This though, could have been (like you mentioned), the result of over stretching on the warp or weft of one or both ends. Hard to say now, it’s been too long, but that makes sense.

Thank you for chiming in!   I (and I’m sure we all do) appreciate you contributing and providing information straight from one of the horses mouth as they say.

Dan

[shurloc]

Ron,


I re-organized your quotes for more clarity in the post. It was for the most part all in one quote as if I wrote it.
[ quote ] to begin a quote in a new paragraph.   [ /quote ] to close off the quote of a paragraph.

I very much appreciate the education there in your post and I don’t mind at all, being corrected. I now know more.
90% of my experience with this issues (and currently), has been on static frames from several different suppliers.   I will say, at the last shop I worked at, we used Shurloc panels.

I’m convinced your Co goes farther than other methods to assure consistency. Having said that, there have been times (at my previous place of employment) when I’ve come across the tops of panel frame stretched mesh that arched at the tops and bottom within the print location (the sweet spot). This would only be noticeable in the 5% dots of a 55lpi on a 305 mesh.  Usually the most noticeable on high mesh, with 55-65lpi, and in the 5% range of tone. The results were to get a moire or distorted rainbow pattern in those 5% areas or near that %.

This though, could have been (like you mentioned), the result of over stretching on the warp or weft of one or both ends. Hard to say now, it’s been too long, but that makes sense.

Thank you for chiming in!   I (and I’m sure we all do) appreciate you contributing and providing information straight from one of the horses mouth as they say.

Dan

No problem at all Dan, you are one of the best minds around in the Screen Print game so I just wanted to make sure you had the right info. I 100% agree with you on the Panel/Trax/Click/etc... panel issue - they basically ripped a piece of mesh off the rolll, stitched a locking strip to it and hoped for the best. Some worked well, others did not. The way these frames and panels were manufactured made it impossible for us to do a fabric panel up to the quality standards we demand and you deserve. That said, I can guarantee you that we stand behind every one of our panels, frames and stretcher tools and will continue to offer only a fantastic end user experience. We only want to help printers become more productive and profitable. At the end of the day, if our products are the right fit for a company, we are happy to help. If not, there are other directions we can help them along to.

Ron

[tonypep]

At JNJ I  learned to finesse the stretching of rollers and panel mesh. The one thing they do not explain is the importance of the dead blow hammer on the stretching table. Keep it handy!