• Inkjet has been a part of the printing and mailing landscape for decades in applications like addressing, coding, and personalization.
• The coated surfaces of matte and glossy papers used in promotional applications present a more substantial challenge for inkjet because the surface does not readily absorb the ink.
• The key advantages of digital printing (e.g., turnaround time, personalization, and just-in-time manufacturing) can have an important impact on customer satisfaction, so raw cost calculations cannot be the only consideration.

By Karen Kimerer

Introduction

High-speed production color inkjet systems have truly revolutionized the document printing market over the past decade. Although these advancements have been clear, paper has played a quieter—yet no less important—role in the suitability of inkjet technology for various print applications. Ink coverage, paper type, and running cost are key factors that ultimately determine whether inkjet is the most appropriate and effective method to use for printing, and these aspects also play a role in the future growth potential for inkjet.

Low Ink Coverage on Uncoated Papers

Inkjet has been a part of the printing and mailing landscape for decades in applications like addressing, coding, and personalization. These highly productive printheads are typically narrow and low-resolution, and primarily suited to monochrome printing via imprinting units mounted on mailing and finishing lines. As printhead technology has improved, we’ve witnessed the development of full-page color inkjet systems that were specifically designed for transactional printing and mailing applications. Direct mailers and book printers also benefited from these systems. The common thread between these applications is that they are often printed using relatively low ink coverage on uncoated papers.

Uncoated papers easily absorb the water-based inks that are most commonly used by today’s high-speed cut-sheet and roll-fed inkjet systems. In addition, at lower coverage levels, it is relatively easy to dry the resulting output without rippling or warping the paper. This development was nothing short of revolutionary for transactional printers and mailers, because it eliminated the two-step process of printing variable monochrome data onto pre-printed offset color shells with logos and other design elements. Transactional printers jumped on this change virtually overnight. Direct mailers who worked with pre-printed shells were the next to benefit, but they often had promotional work that required higher coverage on coated papers. Could inkjet address this need as well?

Higher Coverage on Coated Papers

The coated surfaces of matte and glossy papers used in promotional applications present a more substantial challenge for inkjet because the surface does not readily absorb the ink. This is not a major issue for oil-based offset inks that adhere well to the paper’s surface, but water-based inkjet inks are another story. If proper precautions aren’t taken, water-based inkjet inks may not adhere well and instead collect on the surface of a coated paper, leaving a mottled appearance. This problem becomes even more significant for inkjet at higher coverage levels, where promotional pieces commonly use many graphics, photos, and design elements.

Inkjet system providers use two primary strategies to address this challenge:

• Inkjet-treated papers: These papers have been treated with a solution that enables the inkjet inks to better adhere to the paper. These treatments are generally applied at the paper mill, but they can also be applied at a separate location or even at the printing site. Inkjet-treated papers offer print service providers (PSPs) some assurance that the stocks will perform well for the applications that they print on their high-speed production color inkjet systems. This certainly appeals to PSPs, but the challenge is that adding a pre-treatment increases the cost of the paper and generally forces the PSP to stock two classes of paper: one for their offset presses and one for their inkjet systems. This may not be ideal, but it does address the problem.
• Advanced inks and drying systems: These systems enable users to achieve strong results on standard offset paper stocks. The idea is that these advanced ink and drying systems will allow users to print at high coverage on just about any coated paper. While this addresses the issue, it also adds cost. In general, much of the cost of inkjet printing is built into the inks. Developing an all-purpose ink for multiple paper types adds to the cost. On top of that, more ink is consumed at higher coverage. This makes it extremely important for PSPs using inkjet to understand the costs associated with ink consumption.

Cost Calculations

One of the things that differentiates offset printing from production inkjet is the cost of ink. Offset inks are relatively inexpensive, but inkjet inks are costlier. PSPs at the front lines are learning that using an inexpensive paper on an inkjet project can backfire in the long run because of the amount of ink required to achieve a quality result. Furthermore, the energy consumption costs of the drying units on some of the high-end inkjet systems can add significantly to the cost of a project. If variable data isn’t part of the job, it may then become counterproductive to use digital print technology. Offset is extremely cost-effective at making a lot of copies of the same thing, so it may be the best solution if that’s all you’re doing.

The interplay between area coverage and paper cost is central to the success and future growth of inkjet. It is also at the center of the argument about whether pre-treated papers make the most sense versus sophisticated inks and drying systems. We are in an evolutionary time when it comes to inkjet technology. The market will ultimately decide whether a single strategy or perhaps a combination of strategies will succeed in the long run. In the meantime, keep your focus on the overall costs of paper, ink, and power consumption, and assess the implications that these have on workflow and productivity.

Paper Profiles, Speed, and Drying

Three other factors are also worth considering:

• Paper profiles: All inkjet printing systems offer paper profiles that are designed to achieve the best result with a given paper. There are often slight variations of these profiles related to output quality and ink consumption. If you are cost-conscious, there is a paper profile setting with a name like “Good.” If you aren’t overly concerned with print quality, this setting will work fine and will not cost you as much in consumables. If you want higher quality levels, there are ways to adjust print resolution, droplet size, halftoning, and ink usage to increase color gamut and hold finer detail. These higher quality profiles are generally called something like “Better” or “Best.” It all comes down to the amount of ink you want to use to achieve the results you need.
• Speed: Inkjet systems are getting so fast that their productivity rivals web offset presses for certain run lengths—yet the issue of ink coverage can impact speed as well. You may need to run the system at a slower speed to take advantage of a high-resolution setting and smaller droplet size so that you have better control over the volume of ink consumed. You might also need to slow the system down because the dryers will need more time to dry the ink at high coverage.
• Drying: Did you ever notice how long some production inkjet document printing systems are? This has a lot to do with drying. There are a lot of components in these systems when you consider the imaging heads, the dryers, and the required transport systems, but one of the things that helps is giving the paper some extra “travel time” to dry. In short, the longer that the air, heat, and low humidity of the dryers have time to act on the paper, the better it will dry. The system may even need an extended segment to put some humidity back into the paper to keep it dimensionally stable. As is often the case with dryers, longer is usually better.

The Bottom Line 

Printers and mailers who own or are considering the purchase of a high-speed color inkjet system should look carefully at their application mix and overall paper use. Cost calculations for your system should be closely tracked and include the impact of ink consumption, energy use, paper type and cost, operator cost, paper waste, overhead, and required consumables such as inkjet paper treatments. You must also consider your customers’ requirements for turnaround time, personalization, and just-in-time manufacturing. These are advantages of digital print that can have an important impact on customer satisfaction beyond the raw cost calculations. Whatever you do, your decisions about paper use will be critical to the success of inkjet in your facility.

Karen Kimerer of Keypoint Intelligence has experienced the many challenges of expanding current market opportunities and securing new business. She has developed a systematic approach to these opportunities, addressing the unique requirements of becoming a leader in our changing industry. She is well-versed in 1:1 marketing, web-to-print, direct mail, book publishing, supply chain management, data segmentation, channel integration, and photo products.