Commercial Printing: A Flexography Primer for Labels

I’ve been excited about label printing recently, reading whatever I can get my hands on and looking closely at samples of products at home and in the grocery store. Label printing is a growing field, and I find this thrilling, since many other printing arenas are in decline. One thing that intrigues me the most is the use of digital custom printing in this venue, as well as the relatively new shrink sleeve package printing technology. In a digital world, it’s encouraging to find an area of commercial printing that’s growing and spurring technological advances.

Label printing lends itself to printing technologies other than offset. In fact, the technology of choice is most often flexography. So here’s a brief primer on flexo to help you in your print buying work.

What Is Flexography?

Flexography uses flexible rubber custom printing plates with a raised image area to transfer ink from the press to the printed substrate. This actually sounds a lot like letterpress. And that’s exactly what is is: a contemporary spin on the older art of letterpress printing.

What makes flexography (often referred to as just “flexo”) ideal for labels is its ability to print on substrates that are inappropriate for offset, such as plastic sheets, metallic films, foils, and acetate.

In addition, the water-based nature of the flexo printing ink makes it easier to print on these plastic sheets and films. (Offset ink is oil-based.) Flexo inks can be printed on non-porous substrates, which makes this process ideal for food packaging. Also, flexo inks can be of a lower viscosity than offset inks, which allows them to dry much faster, making flexo a more economical process.

In addition, flexo presses can run very quickly. One article I read described a press operating at 2,000 feet per minute. Along with the quick drying time of the aqueous inks, the velocity of the press makes flexography cheap and efficient.

A Roll to Roll Printing Process

Unlike some offset printing (sheetfed as opposed to web-fed litho), flexography uses rolls rather than sheets of its printing substrate. The unprinted paper or plastic comes off one roll, goes through the press, and then is wound up onto another roll.

In addition to being an extremely fast process, the roll to roll nature of flexography allows for such in-line processes as inkjet personalization, hot foil stamping, custom screen printing, and embossing. And in-line processes are faster and therefore cheaper than off-line processes.

What Kinds of Products Are Appropriate for Flexo?

This is only a short list, since there are many more uses for flexo:

1. 1. wallpaper

1. 1. shopping bags

1. 1. corrugated board (cardboard boxes)

1. 1. food packaging

1. paper and plastic cups

The intense pressure of offset press rollers would not allow such substrates to be printed without being damaged.

The Limitations of Flexography

I haven’t seen much written on the down-side of flexo, but I have seen samples of the printed products under a high-powered loupe. I have seen:

1. 1. slightly coarser halftone screens than with offset commercial printing

1. 1. slightly mottled, or uneven, solid areas of ink laydown, in contrast to the smooth solids of offset printing

1. 1. slightly less precise registration (colors seem to be less precisely positioned than in offset litho)

1. and an odd halo effect, in which type letterforms seem to have a lighter area around both the inside and outside edge of each stroke of each letter.

That said, most people don’t read their product labels with a loupe, so these limitations don’t outweigh the huge advantages of flexography. Plus, you’d be hard pressed to print on corrugated boxes without such a technology (unless you chose custom screen printing to print the boxes). After all, an offset press would crush the fluting in corrugated board.

What This Means to You

In your design career, you may have an opportunity to design labels, bags, corrugated cartons, or product packaging that will be printed via flexography. Therefore, it will serve you well to observe products on the shelves of retail stores to see how the designs accentuate the benefits of flexo and minimize its limitations.

This entry was posted on Tuesday, December 9th, 2014 at 5:24 pm and is filed under Printing. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.