Computer-to-screen imaging systems have helped screen printing to remain relevant as inkjet technology has progressed, but they require a different mindset in stencilmaking for best results.
Digital technology, specifically inkjet printing, was forecast by many to be the death knell of screen printing when the first systems were first showcased at the SGIA Expo in the early 1990s. While inkjet has taken much of the large-format graphics market and DTG printers are extending their reach into textiles, inkjet has not forced screen printing into obsolescence. In fact, the two disciplines seem to complement each other, giving screen printers more choices and variety of services to sell.
The screen-printing industry also embraced digital prepress technology many years ago with the introduction of computer-to-screen (CTS) imaging – systems that image screens directly from a digital file – as a way to advance the process. CTS systems save time and money by eliminating the need to output, cut, tag, transport, repair, and store film positives, not to mention the cost of the film itself. They also eliminate the need for a vacuum frame and glass, saving not just time but also largely overcoming imaging problems such as light scatter and pinholing. Moreover, precision image placement through a CTS system significantly reduces registration time on the press.
Two types of CTS technologies are currently used: inkjet masking and digital direct (or maskless) exposure. Combined with the recent surge in LED exposure systems, CTS technology has given screen printers many exciting new options for imaging and exposing their screens. Looking at the benefits and limitations of these technologies will help clarify which may be the best choice for your business.
Understanding and Assessing Options
Masked CTS systems use inkjet technology to apply an opaque ink or wax onto a coated screen, forming the UV mask traditionally created by a film positive. The screens are then exposed conventionally. Maskless systems instead image and expose in a single step utilizing a digital light processor (DLP) that scans the surface of the coated screen, exposing the negative non-image areas while allowing the positive image to wash out during development.
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