When I was a boy, we had milk bottles delivered to our door. Glass bottles. Boy, have things changed. Now, beverages are just as likely to come in boxes or pouches with straws.
These containers fit into a particular segment of the package printing industry called “flexible packaging.” A PowerPoint series I found by Peter Schottland, produced for the American Packaging Corporation, called “An Overview of the Flexible Packaging Industry,” defines flexible packaging as:
“A package or container made of flexible or easily yielding materials that, when filled or closed, can be readily changed in shape. The construction may be of paper, plastic film, foil, or any combination of these. Includes rollstock, bags, pouches, labels/wraps, lidding, shrink sleeves and stretch film.”
What makes this of particular importance to me is that these are fertile areas for custom printing and graphics. The market is growing, and as a printing broker I find this intriguing.
Further on in Schottland’s presentation, he notes that the increase in flexible package printing is due to lower materials costs than for rigid packaging (rigid cartons, for instance), improved technology, reduced materials consumption, and the benefits of the paper, films, and foils used in this process.
How Do They Print Flexible Packages?
Rotogravure
According to Peter Schottland’s presentation, the main commercial printing technologies used for producing flexible packaging are rotogravure and flexography.
To provide a brief review of these processes, unlike offset lithography rorogravure does not use plates. Instead, the text and images of a page or package are engraved directly into the rotogravure cylinder using lasers, diamond-tipped tools, or chemicals. The deeper the wells engraved on the cylinder (with images, solids, screens, and type composed of dots), the darker the ink. The ink from the ink fountain fills the wells as the rotary press cylinder turns. Then a doctor blade removes the excess ink. Then the rotating rotogravure cylinder makes contact with the web of paper (a roll, not sheets) and deposits the ink on the substrate. Heat dries the ink before the paper enters the next color unit.
As you can see, the process involves a direct deposit of ink, unlike offset lithography (in which the image is transferred from the plate to the blanket to the printed substrate). Also, this is an intaglio process (as opposed to a relief process), since the ink wells are recessed into the rotogravure cylinder.
Rotogravure is a good choice for flexible packaging because it maintains exceptional quality over exceptionally long press runs (millions of images, for instance). In addition, it will allow for custom printing on webs of foil, film, or paper. According to Wikipedia, rotogravure has the “ability to print on thin films such as polyester, OPP, nylon, and PE, which come in a wide range of thicknesses, commonly 10 to 30 micrometers.”
The down side, other than the need to print hundreds of thousands of images to make the process cost effective, is that the text as well as solids and images are composed of dots.
Flexography
Wikipedia defines the term flexography as a “modern version of letterpress which can be used for printing on almost any type of substrate, including plastic, metallic films, cellophane, and paper.”
As noted in prior blog articles, flexography (a relief process, as opposed to the intaglio process of rotogravure) employs rubber plates with raised type and images to print on webs of paper, film, plastic, etc. Lasers or chemicals are used to image the raised plates, which are mounted on the press in exact register. The press inks the plates, and a doctor blade removes any excess ink before the rubber plates apply the image to the substrate.
Again, this is ideal for flexible packaging since it allows for custom printing long press runs on rolls of foil, film, and paper.
Other Technologies
Although rotogravure and flexography are the technologies of choice for flexible packaging, some flexible package printing is done via custom screen printing (for long runs) or digital printing (for very short runs).
Why This Is Important
As with other commercial printing technologies experiencing a growth spurt, it is prudent to be aware of what flexible packaging is, what it looks like, and how it is produced. Look around in the grocery store, and you’ll see little pouches of apple sauce where there were once only glass bottles or metal cans. Learn to identify this packaging, and understand how to print it, and your graphic design skills will stay relevant and in demand.
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on Tuesday, October 28th, 2014 at 2:36 pm and is filed under Packaging.
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