Ink & Ink Dispensers
Printability and colour proofing assured ByTom Kerchiss, Chairman of RK Print Coat Instruments Ltd
I
nks can be engineered to be opaque or transparent; they may be glossy, matte, metallic or fl uorescent. Additionally, inks may be light fast or rub resistant. In order to meet soap and detergent packaging requirements Inks can be alkali; inks may be formulated so that they are fade resistant and even water resistant. The latter includes labels that are printed and then affi xed to drums and chemical containers that may be stored outdoors and are subject to exposure to the elements. Most ink is colloidal: particles are equally dispersed throughout the solution. Inks must be stable, without some form of stabilisation a colloidal system would separate out, the pigment settling within a short time so that ink in a container would quickly become useless. Water based inks for example, can be stabilised through the addition of blended surfactants or polymer.
With careful pigment selection, ink formulators can produce inks that comply with colour objectives. Inks must perform consistently and with no surprises. The colour when viewed must be as expected, both when the tin is opened and when it is run, subject that is to some adjustment on press. If we consider for the moment fl exo for folding cartons, the formulator must allow for the fact that many cartons are printed, die cut, scored, folded, glued and delivered in a continuous operation. This means that the ink supplied must be of a quick drying nature and possess good rub resistant properties in order to withstand the rigours of converting and subsequent transportation and delivery to the customer.
Inks are primarily utilised for their communicative, decorative and to some extent protective properties. For the ink system to be eff ective formulators and others must be sensitive to the needs of the printing process and the way in which the ink interacts with the substrate. Increased brightness, more durability and more fl exibility remain key demands. Converters
who print fl exo might want inks formulated to work at higher densities with fi ner screens at faster press speeds and where possible, the inks and components must comply with waste/reclaim circularity requirements.
Ink producers have a lot to take on board: too little or too much pigment will aff ect colour strength. The type of vehicle used infl uences not just hue and colour values, but also the ability to wet individual particles. Substrates also have diff erent light refl ective properties, making a deposited ink appear diff erently and sometimes not as the customer expected.
Stable inks, a consistent printing process and tight quality control must run right through the process and the use of the ink itself. Variability is inherent in any manufacturing process, the issue, particularly when it comes to printability and accurate colour representation is one of controlling that variability so that it is acceptable.
By keeping lines of communication open and developing partnerships with ink, substrate providers and others in the supply chain reduces the
risk of throwaway, wasted time and the associated cost of reworking. In some cases, it can reduce the risk of invoking of penalty clauses. In order to meet colour targets, colour-matching capabilities must be precise and there must be good ink to press correlation. Printers want colour matches and targets that they can actually print. Manufacturers, the substrate and other providers as well as the printer/converter require systems and devices that can be used by everyone to replicate real-world production conditions to document and when issues arise enable them to take the necessary corrective adjustment.
Quality control and product development devices such as RK Print Coat Instruments’ pre-press FlexiProof LED UV colour communication device can be used for colour matching and to determine how substrates and inks interact over time. Issues surrounding printability such as gloss, durability, chemical resistance, rub resistance and much more can be assessed. Both the UV and LED UV FlexiProof devices diff er from the original award winning FlexiProof 100 in that they incorporate an integrated miniaturised UV curing module.
Additive, resin and ink manufacturers as well as adhesive, substrate and other providers and printers and converters utilise the appropriate FlexiProof in laboratories, pressrooms, research and development and in educational centres, such as universities. Another versatile system is the K303 Multicoater is available with interchangeable gravure, fl exo and meter bar coating heads. As a standard gravure printer the Multicoater is often used in laboratories for quality control on all ink/substrate combinations for colour comparison but also for determining factors such as printability and adhesion.
14
October 2025
www.convertermag.com
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