Printing & Design Tips: FEBRUARY 2009, Issue #91

Printing on Corrugated Board

In simplest terms, corrugated board is the stiff, fluted paper o

The first is flexography

f which cartons are made. Unfortunately, in addition to being light and durable, corrugated board is also easily crushed. That is, when you print on corrugated board, you are basically printing on a spongy material, not a rigid one. So how do you do it?

Actually you have four options, some pricier than others.

Flexography is relief printing (raised images and letters) done with rubber plates on a press (not an offset press, but more like a letterpress). It provides adequate but not superior quality. Sometimes registration is off a bit. And sometimes on corrugated board, you can see the patterning of the fluted cardboard reflected in the uneven ink lay-down. But it’s economical for both small and large press runs, and for simple graphics and pleasing color (one-, four-, or even six-color work), it’s often just what you need. (Keep in mind that you can minimize registration problems and the visible patterning of the fluting by choosing a higher grade of corrugated paper stock with finer, rather than coarser fluting.) Once the board has been printed, it can be die-cut and converted into a box.

Screen printing is a second option

This is basically a process by which ink is forced through a screen mesh (made of polyester or other material) by using a squeegee (this is actually done not by hand but on a special press). A stencil or mask allows ink to pass through image areas while blocking out non-image areas. You can lay down a large quantity of ink (i.e., providing more saturated colors) on practically any substrate. The overall quality is much higher than that of flexographic printing, but it’s more expensive than flexography. It’s also more appropriate for shorter to mid-range press runs.

A third option is called "litho lamination"

Basically, you offset print your design on a coated press sheet that you then laminate to the corrugated board prior to die-cutting the board and processing it into a box. (This is in contrast to flexographic printing, in which you print directly on the corrugated board prior to its being converted into a box.) Litho lamination offers the high quality of offset printing. That is, you get much tighter registration and better quality than flexography, and much finer screens and halftones—i.e., more intricate detail--than silkscreen. This option is appropriate for medium-sized production runs, but you should expect a higher set-up cost than required for the other methods.

The fourth way to print on corrugated board is to print on the paper stock

from which the corrugated board is made (prior to its being made). That is, after the print provider prints on the top sheet of the soon-to-be corrugated board, the converter then laminates this sheet to the fluting and the bottom sheet (like a paper sandwich with the fluting in the middle) and then die-cuts and processes the newly corrugated board into a box. This option is called “preprint.” Set-up costs are very high; therefore, preprinting is only appropriate for very large production runs (think hundreds of thousands of copies rather than a few thousand copies).

When approaching these four options, consider the quality you need first and then the set-up costs and unit costs. Set-up costs (the cost to prepare for the print run) are mitigated by lower unit costs, which decline as the press run is lengthened. Of course such concepts as “long runs” vs. “short runs” are relative, and without specific job specifications, there’s no immediate answer regarding which technology would be the most economical for your job. Therefore, start by determining your press run and quality needs, then contact an offset print provider you trust. Together you can determine whether your job lends itself to flexography, screen printing, litho lamination, or preprint. Then ask your offset print provider to suggest vendors well versed in these processes. (In short, draw upon your printer’s knowledge of these options and his relationships with other vendors.)

Vehicle Wraps

Vehicle wraps have a major "Wow" factor. It’s as simple as that. When a bus goes by wrapped in a full-color image, you just have to turn and look.

But how do they do that? And how does it relate to printing?

The car wraps (and bus wraps) that you have seen share a common printing technology with the huge wall banners hanging from the sides of buildings. Both are produced in strips on a large-format ink-jet printer (a digital press, in the strictest terms). Unlike the ink-jet printer on your desk, however, this ink-jet printer is very large, prints on multiple substrates (such as vinyl), and in most cases uses solvent-based inks that will withstand the elements (rain, sunlight, etc.).

The concept of the ink-jet printing in this case is relatively simple, but the details of installation are a killer.

First the vehicle must be appraised. Specifically, oxidized vehicle paint has a powdery consistency to which the vinyl printed strips of ink-jetted material will not adhere. In some cases adhesion problems can be minimized by rubbing the vehicle down with alcohol. However this is not always the case.

Then the dimensions of the vehicle must be considered, which involves photographic analysis and measurement. For instance, “compound curves,” which extend in multiple directions, demand more skill in applying the printed vinyl artwork.

Printing is the next step, using the wide-format ink-jet printer and the solvent-based inks that are tolerant of sunlight and weather. These overlapping strips (overlapping to ensure registration) are then laid out on the vehicle to confirm alignment before being actually applied. The mirrors, molding, curves, and other “ins and outs” of the vehicle can make a huge difference in the time required for the installation process, as can the placement of design elements relative to these parts of the vehicle.

Then there is installation, which can take more than twelve hours (depending on the complexity of the vehicle). Companies that produce and install vehicle wraps price their service based on the square footage of the printed design and the time required for installation.

First the car is washed and then wiped down with alcohol to ensure adhesion of the artwork. Then the ink-jetted vinyl is applied with a heat gun (with particular attention paid to areas that are curved).

Vehicle wraps are removable, but they are usually produced on “permanent” materials expected to last several years (that is, both the ink-jet printing itself and the adhesion of the substrate to the vehicle). There really is no down-side to this process. It’s durable. It’s removable. The vinyl even protects the paint it covers. If a portion of the design is damaged, you can print out another strip of vinyl to replace the damaged portion. However, if the vehicle paint is already damaged when the procedure is begun, it may be further damaged by the application and removal of the printed vinyl image.

[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]