Extended colour gamut printing

The use of fixed palette printing or extended colour gamuts is becoming more widespread in flexo printing. Earlier this year I visited a customer event at Bobst Bielefeld and listened to some of the arguments in favour of printing with a seven colour inkset.

Dr John Anderson, Director and vice president business development flexographic packaging division for Kodak.

The basic concept is to use just seven colours – usually CMYK plus orange, green and violet – to extend the colour gamut to cover roughly 90 percent of the Pantone range without having to use any additional spot colours. This in turn eliminates the need to washup the colour stations between jobs and greatly reduces the time needed to change the press over from one job to the next. Danilo Vaskovic, sales and marketing director for Bobst Bielefeld, pointed out that there are also savings on ink inventory, adding: “You can reduce colour matching and wash-up times significantly and can increase the production capacity by more than 20 percent.”

This approach is becoming increasingly common in the Americas, particularly South America, and most press vendors believe that it is only a matter of time before their European customers also adopt this way of working.

Consequently, most flexo press manufacturers have been redesigning their presses to run seven colour jobs. This is more of an issue with wide web presses because running heavy rolls at high speeds creates a certain amount of vibration, which leads to registration issues. But as Eric Pavone, Bobst’s head of marketing and sales for web-fed presses, notes: “The print-to-print colour registration needs to be very accurate if you are printing seven colours on top of each other.”

Bobst used this event to unveil its 20Seven flexo press, which was designed specifically with extended colour gamut printing in mind. I’ve already covered this press but it’s worth looking further at some of the aspects of implementing extended colour gamuts. Mostly, it’s a question of beefing up the press to reduce vibration and tightening the plate handling to improve registration.

Bobst has added its SmartGPS system to the 20Seven for automatically setting up the plate cylinders. Vaskovic said that this improves the chances of delivering perfectly round dots and therefore sharper images, adding: “This eliminates the danger of printing distorted dots because the rotating speed of the cylinder exactly matches the force needed.”

Dan Pulling, business development manager at Esko, said that the SmartGPS system is a crucial part of using extended colour gamuts, noting: “Plate mounting has a big part to play, to make sure that there’s not a lot of movement.”

For the demonstration that I saw, Bobst used Kodak Flexcel NX plates. Dr John Anderson, Kodak’s director and vice president business development flexographic packaging division, measured the registration of the plates, saying: “The Bobst process is one of the most accurate that we have seen. The MicroDot shows this and it’s perfect with all the colours aligned.” He added that the plates showed good, bright colours sitting on top of each other that allows for faster, more efficient printing.

Anderson told me that Kodak has a small but growing number of customers using extended colour gamuts, noting: “The presses, the plates and the inks are all there now.”

Luisa Mora, director of marketing and innovation for Columbian converter Litoplas.

One of Bobst’s customers, Litoplas, based in Columbia, talked about the need to have good process control. Litoplas has been using extended colour gamuts for three years. Luisa Mora, Litoplas’ director of marketing and innovation, explained there are two main advantages – efficiency and print quality – adding: “There are no wash-ups or downtime so more time for printing.” However, he noted: “You need to develop the proper foundation to create a sustainable process. You must have standardisation throughout the supply chain. You have to change the collective mindset of the operators and make them part of a team.”

Everybody I spoke to emphasised that the decision to use extended colour gamuts has to be a partnership between the brand owners and the converters. There are savings to be made but these savings have to be passed onto the brand owners and they have to be willing to accept the reduced colour gamut. But as Mora says: “The customers are always looking for something different.”

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