S-mesh problem

[TL]

Anyone encountered anything like this with S-mesh before? 
We set up and printed over 400 shirts for this order, went for lunch, came back and this is how the screen was.  It was still on the press because the order wasn't done.  I checked the ink that was in the screen for debris, nothing.  I checked the edges of the floodbar & squeegee for imperfections(which I also checked before we started) and they were both all good.  Checked all the pallets for anything on them and there was nothing but standard shirt lint.   That head was printing at approximately 32 psi, so I don't think that there was too much pressure or anything like that.  That frame was brand new, we only got it last week and it had not been used before this. 

[ABuffington]

What durometer of squeegee and what angle?  I recommend 65/95/65 or a 70 at 15 degrees.  If the squeegee was set very vertically it can grab the mesh and pull hard.  Some times it helps to put block out over both the frame and coated emulsion, to fill that gap at the end of the screen where the squeegee begins to pull to make it stronger.  Other things to check; off contact of 1/8th inch?, rounded polished  squeegee ends to avoid pulling the mesh?  Distance between squeegee and frame where it begins to print should be about 2-3 inches.  If too close, the mesh may not be resisting the squeegee pull.  Downward force is good at 32.  Was any caustic  haze remover used to clean out stains before this screen was made?

Al

[Nation03]

I have screens spontaneously pop just laying around unused sometimes. I noticed it happens with temperature swings in the shop. Might be a coincidence but I feel like whenever it goes from cooler to really humid and hot, I'll have a screen or 2 pop.

[mimosatexas]

Issues with failure at the edge of the frame like that in my experience are due to burrs on the metal or sharp points of glue, or improper handling causing a cut in the mesh at that point. I have also noticed that holes and tears along the edge will usually not immediately fail, but can last dozens of cycles before randomly failing. Were the pallets hot and left directly under the screen while y'all left? We always offset the pallets for breaks during runs, especially if the are hot from flashing.

[3Deep]

I think that is just the nature of S-mesh, it is a thin thread and tension to 20 to 25 n...I think we've all had them pop, I had one pop right after I finished a run right down the middle.  I like s-mesh and I get them from SpotColor supply, but I also get the saati mesh they carry, prints just as good to me and they tension up just as tight as my s-mesh.

[TL]

There was no haze remover used on this frame before it was exposed, only a quick degreaser because this particular frame had never been used before. 
I think it was probably from a combination of the squeegee being a little too vertical and we did leave the pallets under the screens when we left for lunch.  They were pretty hot and I had never seen that happen before so I didn't even consider that it could be a problem. 
Thanks for the help, now I know a few other things to consider for future jobs.

[Maxie]

What’s your tension.
I was stretching to about a 28n and my screens were popping.
Cut back to 22 and it hardly happens.

[cbjamel]

i have a problem with t-9 and s-mesh with emulsion crackling. whats the cause? over exposure or underexposure? not if that is the right term..
Shane

[Frog]

i have a problem with t-9 and s-mesh with emulsion crackling. whats the cause? over exposure or underexposure? not if that is the right term..
Shane

Crackling? During develpoment? Pictures could help. And, questions about exposure times could lead us to suspect that you are not using an exposure calculator or step wedge test. Say it ain't so.
I'm also figuring that the problem is not not specifically caused by the s-mesh per se, but that could lead to a different EOM which could certainly affect exposure time.

[cbjamel]

While printing. Bottom of screen.
MSp3140- 200 ltu
2/1 coating

Shane

[mimosatexas]

We get cracking at the squeegee edge with s mesh on lower mesh with higher eom, even running at only 20 to 25 psi and with rounded corners. We just do an extra line of tape and no other issues. 2 over 1 is probably enormous eom...