It’s annoying, but keeps happening: all of a sudden, overinking or underinking occurs in the run. Even though none of the settings for the chromatic colors have been changed. The problem is caused by the opaque white beneath the ink not printing consistently. By the time you notice, it’s already too late. Fixing the problem costs time and materials. Up to now, however, this was mostly unavoidable. Because opaque white cannot be controlled in the same way as a normal printing ink – at least not using conventional methods. “Opaque white turns the usual control methods on their head since it lightens the substrate. Higher density means less opaque white and vice versa,” explains Bernd Utter, HEIDELBERG Product Manager for Sheetfed Color & Quality. With Prinect Image Control 4 , print shops can now master this challenge.
Prinect Image Control 4 is the first color measurement and control system in the world to master automatic opaque white control. “We have developed and filed patent applications for completely new algorithms on the basis of spectral measurement,” explains Bernd Utter. This makes it possible to control opaque white with exactly the same precision as the chromatic colors applied on top on it. All that is required is an additional measurement field on the print control strip. The system calculates the deviation from the setpoint values and displays the results on the screen. Automatic ink control can be started with a single tap. The setpoint values are achieved during setup and reliably adhered to across the entire run. This works even with orders where the opaque white is applied over several units, for example in reverse printing.
Prinect Image Control 4 simplifies and speeds up the process of inking up. And reduces the printer’s workload. The printer is shown all the necessary information about the opaque white and colors on the screen in a clear, graphical format. Four steps are usually all that is required to start a run:
1. Select the mode for special substrates:
2. Color selection:
Start by selecting only opaque white. The symbol for opaque white control can be seen in the “Setpoint values” column beside the lab value.
3. Measure the first pull in order to adjust the opaque white:
Wait until uniform coloring of the opaque white has been achieved before adding the chromatic colors.
Example: In the first pull, the opaque white (shown in red here) is still extremely underinked. In the second pull, the values are correct.
5. Activate and adjust the remaining colors:
Production of the run can start now.
“On average, packaging printers save ten to 15 minutes of setup time and between 400 and 500 missing sheets per job,” reports Bernd Utter. The savings quickly add up to several hundred euro, particularly when dealing with expensive substrates like foil, metalized aluminum stickers, or laminated cardboard. In addition, the opaque white not only stabilizes more quickly, it also remains constant and thus ensures uniform inking. Saving the color values for different materials saves even more time. David Rae, Print Champion at the American packaging producer Multi Packaging Solutions (MPS), part of the WestRock Group, is impressed by this: “Most of our orders are printed on metalized cardboard. Opaque white control is by far the most important criterion for us. Saving and calling up the desired color values are now much easier. This makes the whole system very user friendly.”
Another benefit is that Prinect Image Control 4 ensures maximum production reliability, even during the print run, through regular measurement and control. It detects even the most minor color deviations using the spectral measuring technology, even before they are visible to the human eye. Defects and follow-up costs are avoided at an early stage. David Rae again: “Prinect Image Control 4 has not only enabled us to measure the opaque white, but also control it using a normal print control strip. This gives us a reliable basis for optimum control, adjustment, and maintenance of the colors printed on top of the opaque white.” In addition, the system runs detailed quality reports for each job via using the Analyze Point in the Prinect Pressroom Manager as proof of consistent production for the customer. “With Prinect Image Control 4, opaque white can be reliably controlled for the first time. For packaging printers, this means greater costing reliability, greater production profitability, and greater throughput with improved quality,” sums up Bernd Utter.
Even though modern digital imaging software can automate the process of color management, certain aspects will always remain subjective. Having a deeper understanding of the principles behind color management and what choices to make helps printers achieve optimal printing results.
Get the lowdown on colorimetry, densitometry, standardization in printing, dot gain vs. dot loss and much more in our expert guide.