Ink is not what it used to be

Take a look at the cave paintings of the Stone Age and you can see the ancients were already manufacturing their own colours and liquid inks. Mostly made from the available stones such a chalk and ochre, they also used animal fat and blood as well as charcoal from their fires. Inks have been manufactured for centuries although not all colours have been available. The Chinese had already created a range of inks in the third century BCE using charcoal and pine resin amongst other organic ingredients, as had the Egyptians at the same time with the main purpose of writing and record keeping on papyrus and later on animal hide. The issue was to broaden the range of colours from black or a dark brown to help embellish and illustrate texts. To create gold or white was possible but colours such as blue needed the rare blue stone lapis lazuli from Afghanistan, which did not appear in the West until the Middle Ages.

Development track

Finding ways to fix inks so as to retain their intensity and colour has always been an issue since the earliest times. Resins bind the ingredients of ink together blending the solvents and dyes to form a homogeneous mixture. From the earliest days through to the 21st century, getting the balance right as well as avoiding harmful elements is an art form in itself.

Creating new inks is the work of scientists such as Dr Koen Steert of Agfa. He explains: “Ink is always on a development track. To the outside world it looks easy but in reality, it is a period of one, two, three or more years of development. We fully launch a new ink together with a system so there are different segments you have to go through. Firstly there is the scoping phase, what do you want from the new ink, what is the gap in the portfolio that you want to fill.

Then comes a lot of innovative approaches, a lot of jetting experiments on the system proving reliability, proving consistency, achieving and proving your ambition and what you target. Finally, you have to bring that ink up to production scale, and push it to the market to address all the regions in the world.

And that entails not only scaling up but also a patent infringement check and a health and safety check as part of the project.”

Looking back at the history of making inks, some rather unpleasant ingredients were used causing potential health hazards for printers and scribes. Those days are long gone says Dr Steert. He says: “The black pigments in our inks are carbon based but nowadays the pigments we use are organic pigments. We don’t manufacture our own pigments, we source the pigments from big factories that dominate that world, but it is true we no longer use the non-organic health and safety unfriendly pigments in our inks. So, the only thing we have to screen for are the pigments to ensure we get the highest inkjet grade, so there are no reliability problems in the inkjet system.

Secondly, we have to screen for the best performing inks when it comes to ultimate durability. You don’t want a vivid ink on day one but then six weeks later that ink has disappeared completely so that is an important aspect when it comes to screening of new pigments.”

Clear ink

The basis of most inks is a clear varnish which acts as a binding and stabiliser for the mix of ingredients. The search for a pure white ink has been something of a holy grail as has hunting for clear ink. Many firms have achieved this goal and when they do it is worth shouting about. For instance, this autumn Brett Newman, chief operations director at Mimaki distributor Hybrid Services, says the firm’s UCJV printers feature a pure white ink to help create strong colours when printing on transparent, coloured or metallic substrates. The substrate’s properties—and in what conditions it will be used is an important factor. Sunlight, temperature and humidity all play a part in the life expectancy of ink on substrate, so research is vital. Mimaki has announced the availability of a new LUS-170 Clear Ink to be used on the UCJV300 series of printers.

“With the availability of this clear ink for the UCJV300 series, we have employed our proprietary Mimaki Clear Control (MCC) technology for the first time in a roll-to-roll printer,” comments Ronald van den Broek, general manager sales EMEA of Mimaki Europe. “This unique feature shortens the time needed for ink curing to prevent dust from sticking, ensuring smoother, cleaner clear effects, such as a matt or glossy finish. We believe this new ink opens up more possibilities for Mimaki users and enhances the versatility of our award-winning UCJV300 series even further.”

Newman adds: “Utilising flexible UV inks that cure instantly, allows customers to quickly print and immediately laminate or deliver the finished product without waiting for drying. The UCJV printers also feature white ink, enabling users to produce brilliant colours on transparent, coloured or metallic substrates. The introduction of clear ink also places the UCJV300 series into the prototyping and packaging environment. With its layered printing capability, the UCJV300 series can deliver dynamic backlit graphics, or graphics that are transformed with different light sources. UV-curable inks also offer greater opacity with less ink consumption than other ink formulations. LUS-170 ink is Greenguard Gold certified, meaning that it meets the rigorous standards for low emission of volatile organic compounds (VOCs) and is acceptable for use in environments such as schools and healthcare facilities.”

Cambridge connection

As most people are aware although press manufacturers make or specify the inks to be used in their kit, there are always alternatives made by rival firms keen to get a cut in the lucrative market. A classic example is where InkTec launched UVioNova inks for the Mimaki LH-100, LUS-120 and LUS-150 printers which the firm says: “…are significantly cheaper than the manufacturer’s own inks, and offer an improved colour gamut, excellent lightfastness and strong scratch resistance. This all ensures similar printing quality to the Mimaki original inks is achieved but at a much more competitive price.” The claim by InkTec is that users will save 50 percent of the price of using the manufacturer’s recommended inks making it an attractive offer although hard to verify. Mimaki say that it is a false economy as its inks are designed specifically for its printers and will not cause problems in maintenance and servicing and have a longer life than cheaper alternatives. Cheaper inks may also affect warranty and service agreements in some cases.

Getting ink to the substrate is an area that has greatly improved in recent years with the development of inkjet technology for wide-format printers, with Xaar one of the leading pioneers making Cambridgeshire the inkjet capital of the industry. This year, Meteor Inkjet has announced new electronics and software to drive Xaar’s printheads with ‘high laydown technology’.

The technology addresses the need for extremely large volumes of fluid to be deposited at high speed, in a single pass. Examples include gloss, adhesive, lustre and metallic for ceramics; tactile effects including raised varnish, foil and Braille on labels, folding cartons and other packaging; white, black or flood coating; and high build UV 3D printing. Typical digital alternatives require multiple print bars or machines to run at low speeds to build up sufficient thickness and conventional techniques such as rotary screen can be economically unsuitable for low to medium run sizes.

O Factoid: In the third century BCE, the Chinese used ink made from charcoal and pine resin.  O

Clive Ayling of Meteor says: “Fully accessing the benefits of high laydown technology requires a thorough understanding of the printhead waveform, image encoding, line speed compensation and the ink delivery system. Through our long-standing and close working relationship with Xaar, Meteor is proud to once again present a solution which allows our customers to easily take advantage of all that Xaar’s technology has to offer.”

High laydown technology is at the heart of ink technology revolving around its viscosity and how it will flow onto the substrate. Coupled with this essential property are issues around permanence, colour density and their ability to resist the actions of moisture, heat, gas and chemicals. Some inks are designed so they will change when subjected to some of these actions in order to reveal if a product has been tampered with or for other security reasons which require a product to remain intact. Dr John E Bannard is the managing director of Siltech who specialise in what he calls smart ink technology in the Siltech laboratory in Nottingham.

“We make inks,” Dr Bannard says. “We make inks that are dynamic and inks that change colour. If you put any kind of energy into ink whether it’s thermal, radiation or chemical then we can produce an ink that changes colour. It was a direct alternative to inkjet. Where inkjet tends to be unreliable, messy and taints the product—in other words is not very green—we have a better-quality product, a much cheaper product with no ecological issues at all. The printing is not done on the food filling line or at the farmer filling line, the printing is done in the print shop where the packaging is made.”

He said most of Siltech’s clients are manufacturers and are abroad with many in Europe but also in America, Australia and even China. Its products include Thermoprint irreversible colour change inks. The company has inks used for evidence of tampering, for use to check sterilising and brand security as well as surface modification lacquers. In a world where packaging and product security is king, clearly Siltech has tapped into the hush-hush world of security inks.

However hush-hush the world of ink manufacturing may be, inks need to pass strict health and safety considerations. Exposure to some chemicals during the printing process or in the manufacture of ink can potentially cause illness and allergic reactions. The printed substrate must also be safe so if it is subject to heat or moisture it will not cause health issues or contaminate food or other sensitive substances if it comes into contact. Hence the legislation is under the Control of Substances Hazardous to Health Regulations (COSHH), requires ink manufacturers to adequately control exposure to materials in the workplace that cause ill health. This is done by ensuring printers and those manufacturing ink use protective clothing and have working conditions that ensure exposure to lacquers, adhesives, cleaning solvents and ink ingredients is minimised with ventilation and protective clothing.

Manufacturers

With toner cartridges, offset printing inks, inkjet and UV curable inks to name but a few, the world of inks has mushroomed as the technology of printers has expanded. From the humble silk-screen printing of yesteryear to the super wide-format printers of today inks have transformed. In the world of wide-format printing where the products include banners and vehicle graphics, solvent inks have proved to be durable and robust but contain volatile organic compounds (VOCs) which cause health issues although milder solvents have helped to negate the problem. UV-curable inks are ideal for flatbed printing on rigid substrates although care must be taken not to allow exposure of the UV lamps to skin. They dry instantly which has made them a popular choice with no evaporation. Dye sublimation inks are mainly used on textiles where a heating process allows the ink to sublimate or be absorbed into the textile fibres securing strong and vibrant colours.

The UK is known for its ink manufacturers due in part to the invention of inkjet and its development in the last 40 years. Mexar specialises in aqueous or water-based inkjet inks for industrial applications as well as pigmented and dye sublimation inks for textiles. Colourgen has its own brand of inks under the Elite Essentials range of inks made in the UK which are compatible with Epson, Mutoh and Seiko printers depending on the media. Kodak has its own range of inkjet inks which the company developed for its wide-format printers following its switch from traditional camera film and chemicals to industrial printing.

Another ink manufacturer for inkjet is Splashjet as is EFI and Sun Chemical based in America who market its inkjet ink under the SunJet mark. Others include INX International Ink, DuPond, FujiFilm and Bordeaux Digital Printink although there is a very long list as the industry continues to grow with new names appearing regularly.

Printers and sign-makers of a few generations ago would probably not recognise the way the industry has changed with the move away from sign-writing with traditional oil-based inks and silk screen printing with its mix of ink types. Yes, ink technology has clearly come on a long way from the days of Johannes Gutenburg’s early printing press in the 15th century.

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