When you undertake an important packaging prepress project with unusually tight tolerances for the reproduction of both spot and process colors (and eventually also spot colors converted to process), you will need a customized color profile of the press.
This happened to me last year—At a previous employer, I was in charge of the prepress for the U.S. relaunch of a worldwide dairy company’s flagship yogurt product. The reasons why you need customized press profiles may be the same as mine, or at least have similar final requirements:
Image courtesy of IDEAlliance
- The same graphics will be printed in different substrates and/or different printing systems, including (in my case) flexo, gravure and offset, on different substrates like multi-laminated foil/plastics/paper for the lids, laminated paper for the labels, shrinkable plastic for bottles, cardboards for wraps and laminated micro-corrugated for boxes
- All of them will use the same high-quality and complex graphics containing process and spot colors, spot converted to process, and varnishes/lacquers for finishing and protection
These two points mean you need to achieve color consistency among a wide range of substrates and/or printing processes and systems, each with its own tolerances and particularities in tonal and color reproduction. Achieving the greatest accuracy means the least tolerance on each, and will ensure the differences between them are minimized as much as possible.
The Why
Each of the printers you will be working with has its own printing specs and ways to manage its workflow, making printing plates, cylinders, etc. So, first, the golden rule: Communicate with all the printers involved in the project in order to make sure all details and ways of working are agreed upon.
It is also typical that they have their own pre-existing press profiles, so why go to the trouble (and expense) of asking for your own “printer specific” examples for the project? Let’s see what type of color profiles the printers may have:
The way to work with different black generation profiles on the conversion from the source to target color spaces in the prepress process may vary according to the tools used.
- Older press profiles not necessarily updated with the latest changes in inks, substrate suppliers, brands of the plates used, season of the year (if the facility is not climatized), etc.
- Updated press profiles, but ones which are “averaged” between many different presses, or between different printing facilities, or even with other overseas locations belonging to the same printing company. In this case, the averaged profiles are good for all the presses but not good enough for any press in particular, if you are looking for the greatest possible accuracy in color reproduction
- They may have accurate and updated color profiles, including special proprietary profiles (non-ICC) for their proofing systems (like MX4), which can be exported as ICC if needed, depending on the type of tools and software available in your workflow. Again, the accuracy and “authenticity” of these profiles need to be triple-checked; trust but verify is the best policy for success in this area. So, if time and budget allow, you may still want to make your own profiles
The What
Once you are sure and committed to making your own printer-specific profiles, you’ll need to schedule time on the press—which is always scarce in my experience. It is usually advisable to be there for the pressrun of your fingerprint or characterization, in order to make sure the press crews are taking seriously enough the printing specs you provide, the press settings, plate making, etc. and not thinking it’s “just another test” to be done as quickly as possible. All the press settings and conditions, inks, plates and substrates need to be as good—and at the same time as standard—as possible, according to the needs of the project.
You will certainly prepare your own fingerprinting layout containing color test charts like IT8.7 or similar according to the profiling software you are using, and also several scales, marks and control elements that will help verify registration, densities, L*a*b* values, dot gain, gray balance, quality of the printing and plates, etc. (see Figure 1). It is also always advisable to add some ISO-standard images and/or images belonging to the project you are working on, as well as some solids and scales of original spot colors to be used (if any). If the spot colors will be used in halftones or integrated/mixed into the images on the graphics, you may need to also add some customized color test charts that include these inks depending, again, on you having the proper software tools to make multicolor profiles (CMYK+n, MXN, etc.).
Once the fingerprint layout is printed under the best and most controlled possible conditions—meaning controlling densities of the process solids and L*a*b* of the spot colors, dot gain, small dots reproduction, registration, gray balance, absence of printing defects like pinholing, slurring, banding, etc.—you will need to scan the color charts with an automatic spectrophotometer (see Figure 2) and build the profiles with the software tool you have available. Never compromise on the quality of the pressrun for the fingerprint, as the accuracy and ultimately the success of the color conversion in prepress depend on it.
Usually the printers have already performed press optimization/linearization before even printing the fingerprint layout for the substrate on which you need to print. This means they have tested the basic press settings, inks, plate making curves, etc. because it’s likely they have been chosen to print these specific pieces based on their previous experience with the type of substrate and requirements needed. This can even include other areas of certification like scratching resistance, friction properties/COF, ink migration and lamination barriers for the food and other industries, etc.