To print high quality images and be as productive as possible, our equipment has to be in peak form. Screen printing equipment has special requirements.
I print caps, and the first maintenance items I look at are the screen and squeegee. The condition of these two items will decline faster than other aspects of printing equipment that I also monitor. Some of these other aspects will surprise anyone who prints, regardless of whether you print caps, shirts, sweats, signs or other items, but first let's look at cap screens and squeegees.
Cap screens are different from shirt screens, because one side must be a thin bar to print the image close to the bill of the cap. The image might be as close as 1/16" to the inside of the thin bar rather than out in the center of the screen like a T-shirt screen.
When the tension on a screen is minimal, the mesh might shift out of registration during printing and the ink probably will be driven down into the fabric. The color of the fabric can then be seen. So a flash cure and second print are required. That double work can be avoided with tight screens and by taking other steps.
Low tension screens cause ink to build up under the screen. Then the screens need to be cleaned periodically during a print run. The tension will be even lower close to the thin side of the frame, which is the image area, than in other areas of the screen. A tip off to this low tension at the bottom of the image area is a greater amount of ink being deposited.
One of the most important steps to producing top quality images and being productive is using high tension screens. Tension is more important for cap screens than shirt screens, because materials used to make caps, particularly foam front caps, are softer than T-shirts, signs and many other items
Stretch and glue screens, that is, those where the mesh is glued to the frame, probably will need to be re-stretched and glued before a job of any size. A retensionable frame can be used to tighten the mesh without removing the mesh. An aluminum tubular frame will hold more tension than wood.
If the frame is not retensionable, then the thin bar should be steel rather than aluminum, or worse, wood, Tension can be increased by deflecting the thin bar side of the screen in towards the center of the screen before attaching the mesh. Steel should we wiped down with mineral spirits or alcohol to remove the oil so super glue will hold the mesh under tension even through the bar is only 1/8" thick. Once the glue is dry on all four sides, then mesh can be laid over the flat side of the thin bar and glued to the flat side with super glue. (possible exhibit is photo showing deflection of steel bar on cap frame with quick clamp)
Getting mesh tension to a level just short of breaking the mesh is a critical maintenance step to avoid problems that affect quality and productivity. The screen and squeegee are like two blades of scissors that must be sharp to cut ink off and deposit that ink on the surface of a cap.