work hardened screens and ganging images

[jvanick]

we had a discussion at MindsEye about ganging and work hardened screens that if you were running the screens in the opposite direction that it would somehow cause them to become un-work hardened.

I've never seen this behavior, and after our screens have been through several re-tension cycles, they are as solid as they're going be until they rip.

Anyone care to weigh in?

[Colin]

Work hardening is a simple term relating to the release of stored tension between the knuckles of the mesh threads.  Once you have the threads pulled as far as they can go and there is no stored friction between the threads on the knuckles of you fabric, the screen is work hardened.  This typically takes a few print/reclaim then re-tension cycles.

At this point, if you were to try and "un work harden" your screen, you would some how have to force the threads back... kinda... i i have no idea how it could happen...  Maybe if you loosened up your retensionable screen and let the mesh sit around for a day or two .... but then whats the point?

Or maybe the person starting this conversation only puts images on the same end of the screen every single time?  As long as the screen is retensionable, no issues.  I still do not see any real issues if its a static screen. 

I just don't see how it can actually happen.....

[jsheridan]

Put the car in reverse and see if it rolls back the miles...

this is a glaring example of 'this is the way we've always done it' with not a shred of logical evidence to back up the claim.

[ABuffington]

One other feature of mesh is 'staging'.  There is a point in tensioning where more stretching doesn't yield much more tension.  This is basically the point at which mesh will also reach a breaking point.  The stress/strain curve of the mesh shows that both warp and weft have different reactions to tensions.  The closer these two curves are the better the registration in both warp and weft.  I don't see how reversing the direction will 'un-work hardened.  The tension and mesh release from the substrate is the same in either direction. If the mesh has low elongation properties and low accumulated elongation properties from the squeegee forces, running the screen in the opposite direction will not cause further tension loss.

[jvanick]

You are all confirming my thoughts.  The argument being made was that the act of the squeegee was 'combing' the polymers in the mesh, which honestly, I just couldn't see happening.

-J