Part of the key to obtaining the highest tension possible is to have a very clean stretcher with no glue drips on any bars or insertion bars on a bar stretcher. Sand these down (metal) w/ 600 weight wet and dry sand paper, or carefully remove glue drops from rubber capture bars before attempting S mesh.
On Newmans you need to make sure you have adequate corner softening to avoid the sharp metal corner where the roller meets the end of the roller. On some Newmans this is an extremely sharp little square corner. The inside of the channel that the mesh rests on is always problematic since Newmans last a long time and small nicks in the edge are enough to cut fine mesh. There also shouldn't be any dried emulsion bumps, major dents, or dried inks in the channel or on the roller where it rests. Again 600 wet and dry keeps them very polished and smooth. First time out you might want a lower grit followed by the 600 wet and dry.
The inside edge of a Newman is quite sharp. You can fold S mesh under to capture a double layer of mesh. This helps the tensioned mesh rest on mesh instead of being stretched tightly around the sharp inner edge. Another trick is to put a flat, bump free layer of masking tape and wrap it around this sharp inside edge of the channel. Both act like a shock absorber.
To avoid moire run a pencil line along a mesh thread in the long direction of the piece to be stretched so that on the first capture the pencil line is parallel to the channel. This makes for consistent mesh capture and predictable non moire results. For Shurloc panels the mesh is captured well to avoid this. In fact from my time studies, the Shurlocs cost no more if you have a stretch table or a manual op. The time it takes to capture the mesh on a newman costs more in labor than the price of the Shurloc process. (4 captures, 4 softenings all done instantly with 4 clicks of the Shurloc strips. (One other note on Newmans: Always make sure all rollers turn outward the same amount. Older tables and sticky rollers can cause one roller to do all the stretching while the other barely moves. Opposite rollers should always turn the same amount outward. Keep a rubber mallet handy to assist the table, or bump the pulling clamps with the heel of the hand to help the stretcher out. Sometimes the manifold can malfunction as well and not send equal air to the cylinders. When one roller moves outward much more than the other it will curve the thread instead of keeping it straight and this will put a lot of strain on the threads and mesh knuckles.)
One other key point. Too often we get in the habit on Newman stretch tables of just flipping the air switch and allowing the last stretch settings to make the stretching faster. Avoid this with S mesh. Back the air off 1/3 of the way at least so it goes to 6-9 newtons, then bring up the tension on the warp and weft to desired tensions, just takes a few turns but this helps the mesh stretch a little. You can also preserve S mesh by dropping the narrow direction of the frame 1-2 newtons from the long direction. The reason for this is the main print forces are along the long direction, while the narrow width only gets pulled as the squeegee passes. We textile printers use squeegees within 1.5 inches of the inside of the frame. Dropping the narrow direction 1-2 newtons helps prevent momentarily high tension that occurs from the squeegee corner to the inside of the frame as it prints. Eliminates a lot of popping issues on press, especially if you don't round off the corners of your squeegees.
One final trick: You can stretch this mesh on the bias for specialty halftone techniques like square halftones that run vertically. (This is a Photoshop bitmap technique). Stretch mesh at 22.5 or 61 degree angle. Affliction uses this technique a lot. Draw a line along the long direction of the mesh piece, then with a protractor find 22.5 or 61, mark a dot at 22.5 or 61 and on the center mark of the protractor. Draw another line connecting these dots, this will be a 22.5 or 61 degree angle biased stretched screen.
A newsletter we did for this:
http://murakamiscreen.com/stretching-s-and-lx-mesh/OK one more, sorry, I'm gone for a week so I'm putting it all out there now:
We carry another mesh with S designations: LX Mesh
The main difference is less mesh knuckle, the threads look like they go through one another rather than over and under. This creates a much smoother surface for the squeegee and also produces a slightly brighter base plate. The softer outer core of this mesh gives a little to allow better transfer of plastisol. It was originally designed for water base and discharge.
Al
