Without know-how colour means blind flying
The ink producer Zeller+Gmelin GmbH & Co. KG provides its customers with an extensive offer of consultancy services in addition to the delivery of inks and coatings. Making use of an ink supplier’s support can be of great use particularly for packaging printers, when it comes to the optimisation of the production process.
The so-called “black art” of the printing trade is history, even if in the colour area such harmless terms such as ink kitchen and recipe are still in use, which lead to associations for rather everyday tasks in the household. In practice, printing has become a technical process that requires extensive expertise in every section. In the matter of colour, print companies see themselves, for instance, confronted with the demand of costumers for exact colour reproduction and a fast advancing digitalisation in the whole colour communication. Regarding the print of food packaging, the complex topic of legal requirements must additionally be taken into account.
No wonder that the ink producer Zeller+Gmelin has recorded a growing need for consultancy for years around the topics of inks and coatings, that Zeller+Gmelin supplies to its customers. Ink series are already especially designed for certain areas of application. If the conditions in these areas change, because, for instance, new laws become effective or the availability of raw materials is restricted due to updated regulations or supply bottlenecks, inks and coatings must often be modified or newly formulated. For print shops, this always means adjustments of important processes. In many companies, this is seen as a disruptive factor in everyday production. However, during such measures new opportunities also open up for print shops, to optimise colour relevant processes and make them future-proof with the help of competent consultancy and training. You can see three typical approaches:
- Conversion to new ink series
- Installation of a colour mixing system
- Change of ink supplier
The question about which consultancy services make sense in the individual case depends largely on the print shop’s individual situation. “For one thing, the positioning of the company in the market and the existing technical equipment plays an important role. In addition to that, the current need for ink must be analysed and determined, what kind of experience the personnel have in the area of ink,” Jürgen Walther, Head of Technical Support at Zeller+Gmelin, explains.
About colour laymen and colour experts
From practice, he knows that especially regarding level of experience in the area of colour, very different requirements can be found in print shops. “There are companies that have a colour management with formulation and an in-house colour-mixing system. In these cases, the consultancy is often an exchange of information at eye level,” Jürgen Walther reports. “Other businesses that have not yet considered the topic as intensively, logically need considerable more support.”
If, for instance, a print shop requests Zeller+Gmelin to accompany the upcoming conversion to a new ink series with expert advice, it usually happens in the following five steps:
- Analysis of the actual state
- Detailed documentation of the need
- Definition of the suitable range
- Analysis of the mixing recipes
- Change of ink series in production
Analysis of the actual state: Before changing to a new ink series, Zeller+Gmelin will carry out an analysis of the costumer’s current situation in any case. The question in the focus is in particular, in which market segments the company is active and in which way the colour communication is performed. Eventually, the next steps depend, for instance, on how the print shop has reached the colour goals set by the end costumer so far – either by using printed colour fans or through digital colour values.
Detailed documentation of the need: During every conversion, the new colour generation must still ensure that all existing requirements for special characteristics like lightfastness, scratch resistance, chemical permanence etc. are still met. Additionally, it must be noted which processes on basis of the technical equipment must be adjusted. This applies to the production of proofs, as well as for the possible optimisation of the colour mixing process through computerised formulation or automated mixing with a colour dosing-unit.
Definition of the suitable range: With the help of the determined need, the range is to be defined, which subsequently is applied in the print shop. If print shops still work with printed colour fans, it is worth considering changing to a digital version at this point. In the future, colour communication will certainly predominantly be performed digitally. At the same time, it is also worth to consider the use of the monopigmented ink system by Zeller+Gmelin. It offers a number of advantages that are described in the info text with the title ‘purer hues and higher intensity with less consumption’
Analysis of the mixing recipes: Particularly in that respect support by Zeller+Gmelin is of special significance: for one thing because adjusting colour formulations is a complex matter and secondly because experience shows that much potential for optimisation lies hidden in this area. Some colour destinations can be reached more cost-efficiently with a changed formulation. This is feasible, for instance, by reducing the number of components or by decreasing the paint application. For instance; formulations partly contain unnecessary parts of transparent white. In this case, a modification can be achieved so that the application weight of the paint is reduced. At flexo printing a reduced volume of the anilox roller leads to a lower consumption of ink and allows the representation of finer halftones at the same time.
Change of the ink series in production process: If all necessary mixing recipes are on file in the colour data base, the conversion to the new ink series can be made. For this purpose, Zeller+Gmelin offers support on site. In theory, this may seem unnecessary, since many actions are possible via online access without being present on site. Rolf Schönwiesner, expert at Zeller+Gmelin for the sector of colour metrics, says that “In practice, an employee of the ink producer can contribute very much to the smooth conversion as he or she often has great application experience in terms of Colour Management. This ensures that unnecessary machine downtimes, as well as frustrating situations during unexpected colour deviations can be avoided in the first place.”
Conversion effort varies strongly
The introduction of a new ink series is always preceded by the adjustment of all existing colour formulations. Often, this affects more than thousand active formulations. It is obvious that a competent support by the ink producer is particularly valuable for every print shop during this process. Depending on the individual circumstances, the extent of this task can however vary strongly. For a company that wants to change to a new product generation and has a digital colour management, the effort will be kept within a limit. “In that case,” Rolf Schönwiesner says, “digitally defined colour destinations are available. Whether print shops have already used inks from us – and thus already have formulations by Zeller+Gmelin – or if it is a new costumer, is of secondary importance in that case. The data for the colour destinations is decisive. They serve as basis for the formulation of new ink series. Subsequently, the new formulation data is imported into the costumer’s database and through random sample it is checked, if the requested hues can be achieved correctly.”
However, if the print shop is still using analogue technology, the expenditure of time and work for a conversion is significantly higher. Usually Zeller+Gmelin receives wet samples of 30 to 40 colours in such cases. To be able to recreate the mix, a proof of every single colour is made. The proof is metrologically recorded. The data that was determined in that way constitute the colour destination of the new formulation. With that, all new colours are mixed and a proof is made. The results of the proofs will be visually and digitally aligned. If necessary, corrections are made until the hue matches the target. As a result, the print shop receives the new formulations with the corresponding proof.
Mixing list of the ink manufacturer as compromise
A compromise between digital colour values and wet samples is the use of mixing lists. Costumer can order digitalised versions of these lists at Zeller+Gmelin. These include all formulations of an ink series – aligned to a defined substrate. If a print shop requires the colour formulation for another substrate, the mixing list must be adjusted to this individual material. This can be carried out with the help of substrate samples that will be made available to the costumer. After the metrological recording of the relevant material, it is possible to calculate the individually adjusted pantone mixing list by systems at Zeller+Gmelin in Eislingen. This option is particularly used by costumers who do not have the relevant technology in terms of colour metrics.
Among the sectors in which the use of colour metrics is used relatively rarely, is the market segment ‘Metal Decoration’. In that case, the formulation is additionally complicated by the fact that a pre-print coating is usually put on metal sheet before printing. Contrary to a white paper surface as in classic offset print, the substrate in metal printing is only exactly defined in rare cases. In practice, this requires individual formulations aligned to the relevant surface.
Colour fans only digitally in the future
The previous statements illustrate how diverse the topic of colours is for print shops. If end costumers, print shops and printing ink suppliers still use printed colour fans against this background, considerable colour deviations between target and result must necessarily be expected due to its many disadvantages. See Info box “colour fan – standard or source of error?”). In the future, there is a no way round digital technology.
Digital colour systems, e.g. PantoneLIVE, offer the fundamental advantage that the target is, for instance, exactly determined as digital colour destination in the CIELAB colour space. For this reason, Zeller+Gmelin always recommends the introduction of so-called digital fans during the conversion to a new ink series. However, the users should be aware that this is only the first step into the right direction. Even if the hue that needs to be reached is exactly defined by a digital value, further variable parameters must still be considered. Examples include, for one thing, the especially big range of different print substrates in label printing, which have a very big influence on the colour reproduction. Another important factor are the conditions in everyday production under which the colour is measured. One example are the different setting possibilities of spectrophotometers that can also be a source for incorrect measurement.
Changing one variable requires the adjustment of the formulation
If a variable like substrate, the ink itself or the application weight changes during production, it always leads to an adjustment of the formulation. To minimise the risk of initial difficulties during the conversion to a new ink series, it is quite common that Zeller+Gmelin develops a part of the formulation beforehand upon customer request. Usually this is done for often used or especially tricky hues, so that availability is ensured. To enable a visual control on the basis of a physical sample, a proof is also often made.
Print shops with a high share of orders with special colours often use an in-house colour-mixing system. If such a system is newly installed, Zeller+Gmelin provides support on-site if necessary. If requested, costumers are being trained during commissioning as well as during the operation of the system.
Consultancy plus technology in a package
For all changes of the mixing recipes it is of advantage, if the necessary technology, e.g. a suitable proof device, is available in addition to relevant know-how, in order to avoid the uneconomic proofing on the printing machine. For this purpose, Zeller+Gmelin offers its customers a service package that comprises of the training and support as well as the software for colour metrics including proof devices with appropriate dryer. Thereby, companies can successfully manage the complete conversion of an ink series, if they have had no experience in this area so far.
A competent consultancy of the ink supplier can prove very helpful even for seemingly secondary aspects. One example is nomenclature of the colour formulations. From practice, Rolf Schönwiesner knows many cases in which some hues exist several times and under different name in the system, if they, for instance, have been assigned to different substrates.
Digital requires systematic structure
Against the background of the omnipresent digitalisation, an exact designation and clear structure of data is of great importance. For a data base with colour formulations, consistent logic is the basic prerequisite for every print shop that the important colour communication with customers and colour suppliers can work smoothly in the future. That is why Zeller+Gmelin also offers its customers to support the development of a sensible name and organisational structure.
“The entire industry is facing the challenge to accomplish the digital transformation,” Jürgen Walther outlines the current situation. “With our offer of consultancy services for all tasks around the topic of colour, we can accompany our customers on their journey to the much cited Industry 4.0. A common industry standard would certainly be desirable; however, it will be hard to establish, as long as the idea of individual companies regarding the details of such a structure is so different.” The development will certainly make sure that wet samples are preferably replaced by data everywhere, so that the advantages linked to it can be used. Eventually, the goal is to establish a workflow in print shops, in which a special colour is exactly defined in the order data already at the receipt of order. The colour communication based on that must subsequently generate exact specifications for the pre-print stage and the mixing of colours and at the same time include substrate and characteristics for later application.
Printed colour fans - Standard or source of error?
Regarding the print of packaging, the information about the colour is often still communicated on the basis of printed colour fans in practice. Many parties that are involved the production chain; from designers to print shops erroneously consider this instrument as colour standard. In general, however, it is to be assumed that printed colour fans are not the standard. The included hues can change strongly due to various influences. The used inks have, for instance, a low lightfastness and the paper contains optical brighteners. Furthermore, the layer thicknesses often deviate from the relevant case of application. That is why colour fans are only valid for one year and not suitable as colour-binding print template, among other things.
Therefore, digital colour systems will prevail. For a trouble-free communication on the basis of colour data, it is then, however, also necessary that the type of colour data is exactly defined and that one works consistently with uniform measurement conditions, colour spaces, etc. Bottom line, the digitalisation in colour communication offers a considerable potential for optimisation. Primarily, time-consuming and costly complaints can be minimised. Furthermore, special colours that a print shop orders from the ink supplier exactly match the target. If the print company has its own mixing system, the formulation for a new special colour can be transferred without any problems. With the help of a remote-connection, the costumer can even receive online-support for a difficult hue. All these measures significantly increase the production safety.
Strong colours with less consumption
If a colour conversion is pending and when it comes to the question of a suitable range, the monopigmented ink system by Zeller+Gmelin comes always into play by default. If the user is prepared to decide for a complete solution, many advantages open up. Since only the required pigments for the formulation are used, the mixtures are more intense and purer. Thus, given special colours can be mixed more precisely. The higher colour intensity also allows the reduction of the layer thickness and thus savings in terms of ink consumption. In halftone printing, a reduced dot gain can be seen. Furthermore, the risk of metamerism appearances (hue shifts under different light sources) is minimised. And from experience it can be said that also the costs for the storage of the inks as well as for the disposal of the residual inks decrease.