While it might be safe to say that we do it all the time, it’s incorrect to accept that there’s an effective and accurate way to predict the overprint behaviour of spot colours that print on top of one another. Each print process overprints differently. Flexo does not overprint like gravure – the ink film thickness and trapping properties are very different. Using typical L*A*B*-based measurement, the industry has become adept at making solid colours appear similar across different printing processes.
This is where the current technology stops. Historic colour management methods have required measuring the behaviour of each particular condition of a specific press on the actual substrate (fingerprinting). This method of predicting press behaviour works well for CMYK offset on standard paper substrates but clearly breaks down for packaging applications where colours in the file are arbitrary, the print rotation on-press is non-standard, and the ink formulas change – as well as the interaction of a host of other variables in the production run. Extended gamut press fingerprinting is expensive, unreliable and often produces useless profiles. To address the needs of packaging, a new approach is required.
GMG has introduced OpenColor, a system that predicts actual ink behaviour on a specific substrate for each press set-up – without the rigors of ‘proprietary chart-based’ press fingerprinting. This technology uses ground-breaking process modelling algorithms, coupled with spectral ink measurement , to analyse ink pigments within each ink colour, as well as the substrate’s colorimetric properties.
Until now, the overprinting behaviour and colour interplay between CMYK and spot colours could only be reproduced by combining a CMYK profile with spot colour libraries. This method required considerable effort to depict all possible combinations of spots and process colours ‘as accurately as possible’. The major drawback was the inaccurate simulation of spot colour overprints.
With increasing use of multicolour printing, the simulation of spot colour overprints currently poses one of the biggest challenges for packaging printers. GMG OpenColor is the first profiling tool on the market that provides this vital capability.
Offering an astonishingly accurate prediction, GMG OpenColor creates high-quality multicolour profiles simulating the printing behaviour of diverse printing technologies, media types and screenings.
What does this mean to the packaging industry?
Press fingerprinting for offset, flexo and gravure printing incurs huge expenses. This high cost often yields poor results, raising costs even further, especially when the cost of customer satisfaction erosion and rework is factored in.
The latest technology improves the final result (greater customer satisfaction) while greatly reducing fingerprinting costs. Once the ability to predict overprint behaviour is available, the next step is for producers of packaging to eliminate inks not needed (usually C, M, Y or K), achieving acceptable gamut through the use of mostly line colours. This allows prepress companies and converters to eliminate colours within a job (without changing its appearance), reducing the number of press stations needed, without compromising the line colours required.
Although this is being done today, the creation of this type of artwork is very expensive and often created with trial-and-error methods. As better ways evolve to produce these separations, the overall reduction of inks on-press will further reduce costs across the entire supply chain.
[Ed’s note: Midcomp is GMG’s official South African agent and enquiries should be directed to email@example.com.]