Extended Color Gamut printing, also known as ECG, finds itself in a growing interest. ECG’s operational and sustainable advantages are obvious and therefore recognised and embraced by a growing number of packaging and label printers including those using flexo or rotogravure. However it is web offset’s combination of high printing quality and broadest press specifications that provides the best ECG performance.
Earlier systems, like Hexachrome (6 colors) and Opaltone (7 colors) , were based on similar ideas of offering a wider color gamut and reducing the use of spot colors. However, these systems never made the major breakthrough.
The situation has changed quite positively. ECG makes use of the well-known 4 standard process colors cyan, magenta, yellow and black, extended with 3 additional process colors orange, green and violet, although other combinations are also possible. Today adequate prepress software for the conversion of most PMS spot colors to ECG colors is available from various providers.
Advantages of ECG
- Always the same set of 7 standard colors on the press and in the same printing units
- Significant reduction of the number of PMS spot colors used
- Less color changes and less wash-ups provide significant time savings
- No color mixing, nor color matching on press, no obsolete ink stock
- Reduction of ink waste and washup liquids, especially in comparison to roto and flexo
- Standardisation in stock keeping, easy, clean, and economical
- Quick response on any job with special colors (No ordering nor waiting time!)
- Allows combination of different SKU’s with different colors in one production run
ECG requires standardisation
ECG requires a good level of standardisation of pre-press and press procedures, and a printing process with an accurate and stable color-to-color register. As there is no international standard for ECG printing of flexible packaging and labels, custom standardisation regarding prepress operations and automation, consumables and printing procedures is required to obtain the full benefits from ECG.
Of all printing technologies offset holds the strongest cards when it comes to ECG performance and execution. The high-quality printing, register stability, good reproduction of the finest screens and a broad choice of screen types make offset ideally suited for ECG.
- Web offset is capable of printing very light screens down to 1%
- Web offset has a broad choice from a range of screen types, from fine AM screens to FM, and hybrid or crossover combination screens.
- Web offset offers accurate and stable color-to-color register.
And in web offset standardisation of consumables, pre-press and procedures, from fingerprint to color profile and color conversion are well established.
ECG-Plus
In practice, it turns out that not all the colors of the PMS color gamut can be reproduced with ECG. It is strongly depending on the expected and thus allowed ΔE tolerance between the target and the real printed color. The claim that with ECG 90% of the PMS color gamut can be reproduced is only valid when a sufficient large ΔE tolerance is allowed.
Modern color conversion software can predict up to which ΔE value a PMS color can be reproduced with ECG based on the available color profile for a certain combination of press, ink and substrate. The use of one or more PMS colors is still required if the calculated ΔE tolerance is not acceptable.
In practice, a tolerance of ΔE2000 = 3 is commonly used and accepted, but broader and narrower tolerances can also be found. Utilising a narrower ΔE tolerance results in more exact PMS color reproduction but at the same time it limits the number of PMS colors that can be reproduced with ECG. Therefore it is logical that even with an accurate and performing ECG process some jobs, or
SKU’s, still require the use of one or more PMS colors, which leads to the forementioned inefficiencies and loss of production time.
DG-AUXO modular web offset press. Configuration with 10 offset colors + 1 flexo unit for OPV or white and EB curing
Efficient ECG with DG-AUXO modularity
To maintain the full benefits of ECG it is important to keep the 7 ECG colors on the press and in their standard position. The PMS colors are printed in one or more additional print units. With this approach, PMS colors are only replaced by other PMS colors and only when needed. The standard 7 ECG colors are always available serving the majority of jobs and SKU’s, offering a maximum versatility
with best efficiency.
The completely modular design of the DG-AUXO web offset press series from DG press allows optimal and customised press configurations for any portfolio or combination of jobs. In addition to the 7 printing units for the 7 fixed ECG colors a DG-AUXO can have up to 5 additional offset printing units, in up- or down-stream positions. The extra offset printing units provide additional functionality for first down white, last down white, PMS colors or special inks for security features, without compromising the advantages of the 7 fixed colors. In this way the DG-AUXO fulfills all demands for flexibility and versatility while maintaining the highest quality and efficiency. Interested to know what DG press can do for your conversion to ECG web offset printing, please contact DG press.
