6 February 2014
By Dean Derhak
When sign shops and other large-format print service providers (PSPs) are surveyed with regard to how much their ink costs per square foot of printed output, two out of three shop owners say they do not know. And when asked how much ink they waste in their production processes, again, few actually know the answer. Some even admit they would rather not know, lest they discover the depressing truth about lost profits.
Under these conditions, effective colour management and media profiling can help large-format PSPs cut their ink costs. Tracking ink use, specifically, can lead to increased profits.
Understanding ink costs is just a good, basic business practice. It can help a sign shop better quote its jobs while reducing ink use and waste. A typical print shops that spends $35,000 per year on ink can learn to reduce its use by 15 per cent, leading to additional profits of $5,250 per year. Smarter colour management may save even more.
Calculating average ink costs per square foot of printed output is easy. It is simply a matter of dividing the cost of ink used over the course of a month by the total area printed during that same month.
First, these figures need to be tallied. Most of today’s raster image processor (RIP) software packages offer a job log, which measure the area printed by tracking substrate use. Some RIPs show the total printed area per job, while others only indicate the width and height, thus requiring the user to manually calculate the area.
There are also other ways to determine these figures. Some printers have built-in web servers that indicate print area per job. There are even apps now that can display this information on smart phones and other mobile devices.
Tallying ink costs, meanwhile, merely requires the shop owner to count how many ink cartridges are used up over the course of the month and then multiply that number by the price per cartridge.
By way of example, a sign shop might print 44.6 m2 (480 sf) of output in one month and pay $390 for the ink used by these graphics. This means the average cost is $8.74 per square metre ($0.81 per square foot)
Importantly, this formula factors in any unused or wasted prints. It also takes into account any inkjet printhead cleaning and purging. What this means is the shop can work out its true costs of ink per square metre, not just the costs of regular ink use itself. The factors that matter most are how much is spent on ink and then how much is actually printed.
Some shops, for example, quote all jobs with a single per-square-foot cost, but not all jobs use the same amount of ink. When shop owners truly understand ink costs, on the other hand, they can quote jobs based on low, medium and high ink use, so as to ensure profits on each type.
Ensuring effective colour management
When a wide-format PSP is starting up, it is essential to obtain the right ICC media profiles. A surprising number of shops mistakenly use one generic media profile for all of their substrates. Then, in the event of a problem, they use colour correction adjustments in their software. Not only does this practice waste a tremendous amount of ink—often without the printer operator realizing it—and thus escalate costs unnecessarily, but it also makes spot colour matching much harder.
So, it is important to set up ICC profiles for each printer and substrate. Then, the matching profile can be selected each time a printer’s operator changes media.
Getting the profiles is very easy, as they are typically available from printer manufacturers, substrate suppliers and RIP software developers. For complete control, however, it is better to develop one’s own ICC profiles. While this requires additional upfront training and costs, the investment will pay off over time, as the shop staff will know best how to reduce ink costs during production while maintaining customer satisfaction with the end product. High quality, after all, is whatever customers say it is.
Using the right inks
One good way to start reducing costs is to avoid ‘light ink’ use. Wide-format printers equipped with light magenta and light cyan inks—which are formulated with less pigment and more clear liquid than regular inks—tend to use them a lot, even when they are not needed.
The sole purpose of these light inks should be to improve image smoothness for close-up viewing, but the effectiveness of this technique depends on the application and its required viewing distance. Most wide-format graphics in the sign industry, after all, are not designed for close-up viewing.
Reducing the use of light inks can save up to 25 per cent of annual ink costs. The colour gamut will not be heavily affected, as dark colours will still be dark and the grey balance will be maintained, even if images look less smooth up close.
Another cost-reducing technique involves producing grey and black in different ways, using the grey component replacement (GCR) curve control in the software used to make ICC profiles. Most default ICC profiles use a lot of cyan, magenta and yellow (CMY) inks when printing greys, but this process consumes up to two-thirds more ink than necessary.
The setting will depend on the media—backlit prints, for example, require a lot of ink anyway—but selecting a GCR curve that replaces CMY inks with black ink when printing grey and black can reduce costs substantially, with little negative impact on printed graphic quality. And even with some loss in detail, this option will deliver richer blacks.
Some ICC profile software engines even have ‘Max K’ settings that replace CMY with key/black (K). This technique can potentially save another 20 per cent of ink use per job.
The disadvantage with this technique is upon close-up viewing, small black ink dots—known as ‘peppering’—may be visible in the graphics’ highlight and mid-tone areas. Also, if this technique is overused, the colours could be ‘blown out,’ reducing some detail in shadows.
Again, where the levels should be set will depend on the media and on the intended viewing distance, so it is essential to experiment a little first to ensure customers will be satisfied with the results. In any case, the technique is definitely worth considering, as it can dramatically reduce costs.
Profiling for purpose
It is also worthwhile to move beyond default profiles by profiling media specifically for their purpose. Many PSPs use just one profile for a printing mode, regardless of the viewing distance required for the finished graphics. In many cases, operating this way wastes not only a tremendous amount of ink, but also a lot of printing time.
Profiling the same printing mode in different ways for different purposes will prove more cost-effective. In a high-quality printing mode, for example, which is typically slower and needs lots of ink, it is easy to end up overusing the ink. The output may look fantastic, but the same result could be achieved with about 20 per cent less ink. This is especially true when printing on coated media, which tend to soak up ink.
While most wide-format inkjet printers have the high-quality printing mode associated with the default ICC profile, signmakers can set up their own profiles for ‘speed’ and ‘economy’ modes to save ink, time and costs.
For speed printing mode, this would involve reducing the use of light inks, setting the GCR to Max K, reducing the print resolution in terms of dots-per-inch (dpi), choosing unidirectional printing and reducing the number of passes. This is the best mode to select for time-sensitive printing jobs involving graphics intended for long viewing distances.
For economy mode, regardless of how much ink the media can handle, the process involves arbitrarily reducing ink use—including both light and dark inks—by 20 per cent and following the same settings for speed mode. The results will often be indistinguishable.
Of course, these in-house techniques take a bit of practice, with consideration given to specific factors like printer temperature settings and different media characteristics. These are all colour management variables that can be controlled to a sign shop’s advantage, yielding new savings.
Also, there is no obligation to pass along the savings achieved through colour management techniques to customers in the final product price. That, as they say, is the bottom line!
Dean Derhak is a product director at SA International (SAi), which develops RIP software. For more information, contact him via e-mail at email@example.com.
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