Expert's Opinion

Rotary screen printing sets the standard for distinctive labels and folding cartons

By Sangeeta Sachdev, Managing Director, SPGPrints America | February 16, 2017

It is often used in the first printing sequence for printing white, no-label look applications.

With vibrant colors, special effects, automated and simplified prepress workflows for shorter runs and fast-changeovers, the case for rotary screen is compelling.

An important consideration for label and carton converters is to think beyond the process. With brands vying for the consumer’s attention on a competitive and crowded retail shelf – and the typical store carries nearly 40,000 SKUs – shelf impact is vital to make sales. Defining your operation by your process with the attitude that, “I’m a flexo printer,” (or, litho, gravure, or digital) can narrow your vision unnecessarily. 

As a complementary process, rotary screen printing can enable converters to offer a look and feel of true distinction for labels and cartons, taking products to new levels of quality.

Its unique ability to lay down thick layers of ink and varnish, between 5µm and 250µm in one pass at speed, means a host of high-value effects can be added to the label or package, productively. Moreover, adding this process is relatively easy – a range of units can be added to almost all of today’s presses, and with laser imaging systems and long-life screens, workflows are fast and cost of ownership is controlled.

Added-value effects with rotary screen
Rotary screen is the most effective and reliable method of ensuring opacity. For that reason, it is often used in the first printing sequence for printing white, no-label look applications, to be overprinted with the brand’s visible colors, preventing see-through and providing stark contrast with the container’s contents.

Tactile and high-luster screen varnishes have been increasingly demanded for wine labels in recent years. Adding a varnish layer thicker than 26µm is usually sufficient to create the tactile effect and give vividness to the underlying graphics. Other popular creative varnish effects include patterns of fine lines and juxtaposed matte-gloss varnishes.

As a stencil process, rotary screen is uniquely capable of depositing large particles that need sensitive handling. Inks for glitter effects – another effect hotly demanded for personal care and luxury food products – are a prime example. Rotary screen is also a waste-free alternative for metallic effects, and for functional features like security holograms, optically variable inks, warning symbols and Braille dots.  

Productive, efficient workflow
Rotary screen is a productive process, especially when using nonwoven nickel screens. This screen has the robustness to run at up to 450 fpm; moreover, it is easy to handle and can withstand multiple re-imaging cycles. The reusability of nickel nonwoven screens is an important efficiency advantage, especially for printers facing demands for shorter production runs, just-in-time deliveries, as well as more frequent repeat orders and label design changes. Because of its strength, the reusable nickel nonwoven screen can be used beyond narrow web applications to 39" printing widths, on folding carton printing lines. The latest screen innovation is a mesh with 405 holes per linear inch. This is helping major label printers, especially in Southeast Asia, reproduce clear, vivid small text and oriental text on self-adhesive labels.

There are a range of rotary screen units, suited to space and application requirements, that can be integrated with flexo, litho and gravure lines. Units on a sliding rail above the press can be effortlessly repositioned in the printing sequence. Portable cassette units can be interchanged fast with other processes in the main frame of the latest-generation presses.

Time-to-market is an increasing concern, and advances in digital laser imaging for rotary screens meet this challenge, eliminating lengthy prepress processes. No films, no chemicals, just clean, sharp, high-resolution images and repeatable results. 

High-performance equipment alone won’t do; the technology provider must prodide the training and application know-how to ensure you gain the most from your investment. At SPGPrints in Charlotte, for example, we provide both a local engraving service, as well as R&D resources at our Demo Center.  

A supplier with a wealth of experience not only of rotary screen, but of workflows, integration and specific applications, will help ensure the success of not only the screen components, but the whole process.

As a converter, you’re looking for a long-term relationship with your customers. Find a supplier who wants a long-term relationship with you, and you’ll be amazed what today’s rotary screen technologies can do.

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