Case study on digital colour communication in printing processes
von Ansgar Wessendorf,
As a result of advances in digitalization, a lot has changed in the packaging and printing industry in recent years. How digital colour communication compares to the conventional process of ink formulation was tested by Saueressig in cooperation with the packaging manufacturer ppg > flexofilm.
Colour creates a lasting impression
Printing ink transforms packaging into a lasting impression for consumers. Colour helps products and brands to express their identity, as it is the first thing that catches the consumer‘s eye on the shelf. Not only from a marketing point of view but from an aesthetic perspective, a balanced colour concept and consistent colour control are extremely important. Standardized control processes at multiple supply chain production sites and consistent print quality of the final product are top priorities and have clearly defined checks in place to ensure colour standards are maintained.
Until now, the process of colour control has been associated with an enormous expense of resources such as time, material, and energy. To ensure colour fastness on packaging, physical mock-ups are produced, long set-up times are required at the press, test prints are run, and print approvals are made in person on site.
As an international provider of services across the entire prepress stages of any design implementation, the Saueressig Group has been offering comprehensive expertise for decades relating to rotary print tools for gravure and flexographic printing processes, embossing rollers, cutting and creasing tools, as well as special machine construction. Since 2018, the Saueressig c.INKTEC innovation center has been adding a space for creative ideas and product innovations to the portfolio.
A key objective of c.INKTEC is to create a more sustainable and transparent supply chain – and this relies on digital value creation, intelligent systems and innovative services, while at the same time aiming to avoid costs and routes that are currently one of the biggest pain points for customers. In this context, the use of the cloud-based software solution c.CLOUD is of great importance. It offers the opportunity to conveniently handle digital colour communication between all stakeholders and provides complete transparency in terms of consistent colour management.
With a wide range of laboratory and testing facilities, the Innovation Center at the Saueressig site offers comprehensive support for any kind of packaging development. By using various pilot machines, it allows for the creation and testing of inks for gravure, flexo and offset printing.
The challenge of inconsistent colours
Achieving colour targets through visual matching while maintaining colour controls and achieving excellent print quality at different production sites is a top priority for retail brands and printers. Product packaging and the associated consistent brand identity must meet the highest quality standards. A process that poses several challenges when using conventional ink formulation and profiling solutions, as multiple interfaces in the process chain increase the potential for errors in colour communication significantly.
Until now, ppg > flexofilm had to check and profile all colour values for each print job in order to manage colour consistency. In conducting a case study in cooperation with ppg > flexofilm, the colour technicians from c.INKTEC have tried out the benefits of the innovative process. Under production conditions, the formulation and settings of inks for printing flexible packaging using the gravure printing process on a Rotomec RS 4004 press were testet. The conventional process of ink setting using purely visual methods was compared with the new digital Saueressig c.INKTEC workflow. Both processes were qualitatively compared and tested by spectrophotometric measurements.
Colours on the test bench
The c.INKTEC team first examined the conventional process of formulating colours in the area of film packaging, in order to determine the resulting efforts and costs. Under conventional conditions, the inks had to be measured using a physical colour sample ahead of the printing process. Based on this, a recipe was created. This was followed by ink mixing in the ink metering system with an automatic mixing unit. After a viscosity test, a preliminary proof was made on a laboratory test device. The ink formulations had to be adjusted and proofed several times to create a starting formulation for the press. With the aim of achieving the defined colour targets, four additional colour corrections had to be made on the press during makeready, based on the specification, substrate, and printing behavior. After a weak point analysis, the technicians converted the process to the c.INKTEC workflow and carried out a cross-check under otherwise identical conditions.
Colour communication and formulation
In contrast to the conventional process, the c.INKTEC workflow already integrates within the design to print process at an earlier stage, enabling a smooth and continuous colour communication from the beginning to the end of the process chain. Ahead of the printing process, the c.INKTEC team matched the ink to the required specifications for gravure printing and adapted it to the original substrate.
For this purpose, universal laboratory printing presses are available at the innovation center. As an integrated solution, the experts were able to transfer the ink formulation to multiple substrates. Adaptation to flexo and offset printing are also possible. By creating the ink formulation in the laboratory environment, the printing inks could be tested and validated in advance. The colour separations could be used to adjust the repro data, in order to subsequently achieve the desired result on the production machine. The cloud-based software solution c.CLOUD also came into use. It centrally stores all the information on the colours that have been created as well as the associated ink formulations, and can be reached anytime, anywhere in the world.
The downstream process took place on site in the ink metering system at ppg > flexofilm. Here the c.INKTEC ink formulation was fed to the automatic mixing system. The inks were dispensed in a 20 kg container and were already provided with gravure solvent mix. To restore the ratio to the original, the inks were recalculated in advance at a ratio of 70% to 30%. To obtain a comparison with the conventional process for the study results, a viscosity test was also carried out and a press proof was produced. Compared to the conventional process, however, the ink only had to be adjusted once. The press was then set up and the print result compared with the colour master. The colour correction in this process could be cut down to one pass on the press, which also reduced the maculate of the press proof significantly.
Developments that pay off
As the results of the case study are consistently positive, it is shown once again how important a holistic solution approach is in order to receive a good print result and to significantly reduce correction loops and setup times in the print shop. The time required to create the ink formulations of the respective spot colours for ppg > flexofilm is reduced by 100%, as they are created upstream in the c.INKTEC laboratory, independently of the printer. A saving of 67% has been achieved in colour separations and corrections prior to production. At the same time, there is a considerable reduction in resources in the print shop. The time required for adjusting the inking units was reduced by 75%, as manual intervention in the printing process was reduced to a minimum. Respective material costs for press setup were also minimized by 40%.