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Under the Hood

Presstek Waterless Printing

With pressure on printers to reduce their overheads, pay attention to their environmental-impact, and produce the highest quality products, Brian Sims offers a solution to achieving all three

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(Above & below) The Zahara plate range can also be used for narrow width web offset printing with applications such as label printing and compatibility with presses such as Codimag Viva 340/420

There’s more to printing than H20

Samuel Taylor Coleridge sums up in the Rime of the Ancient Mariner what most press rooms look like: “Water, water, everywhere, nor any drop to drink”. Press rooms consume significant amounts of water in either the process of printing, the cleaning of plates in the processing of them, and the constituent parts of a lot of the chemicals used throughout the process.

Without water the traditional printing process would not be possible. The art of lithography from the earliest of days works on the process of two substances opposing each other; in this case, ink and water.

At metres a second on a modern printing press, the aluminium printing plate has a battle taking place on it with the water and ink being attracted to one part of the etched plate and not the other. Neither the twain shall meet, producing an image on each sheet of paper that passes through the press.

Like lots of processes or equipment we now take as common place, they may not be the best of options or efficient solutions. Indeed, there is a well-known joke about a tourist in Ireland who asks one of the locals for directions to Dublin. The Irishman replies: "Well sir, if I were you, I wouldn’t start from here." Likewise, Felix Wankel once said of the comparison of his rotary engine design against a traditional reciprocating engine: "Why when you want rotary drive do you start with vertical linear motion?" The common truth is that if your goal is a new way of doing things, then it may be better to start afresh, rather than attempting to tweak a system you have inherited.

Like lots of processes or equipment we now take as common place they may not be the best of options or efficient solutions

Much could be said about modern lithographic printing, we use two substances fighting against each other to produce our product. This takes skills to maintain the balance between each. So why not get rid of one of them; the water? Rethink printing today and you may not start with trying to balance ink and water as a starting point to produce an image due to the issues that it throws up.

A third way

Well if you want to consider this, Presstek are one of the leading suppliers of waterless printing plates.  Waterless printing has been around for some years and there are companies like Park Lane Press in Wiltshire that have built very successful businesses on the technology. 

So, what is the background behind this technology and why is it not more widely used if it is so simple?

To understand the process, you need to take a step backwards and look at the plate itself. Waterless printing plates are the same as wet offset plates in as much as they are around 0.3mm thick and are made of aluminium.

The difference comes with the coating on them where the ink laid prior to printing.

On a traditional printing plate, the surface is etched with a surface that is prepared to attract water. The required image is formed on the plate with a polymer coating that attracts ink and resists water. Water is applied to the plate, which is attracted to the etched area and then the ink, when applied, is attracted to image required. The whole emulsion sits on top of the plate.

A waterless plate is different in as much that only one substance is applied; ink. To achieve the ink concentration needed for producing the image, the aluminium base plate has a top silicon surface, which is etched away. And it is here the ink is retained that is required during processing. On a waterless plate the ink sits in and just above the etched silicon, in turn producing the image needed. It sounds really simple and straight forward. Waterless printing is actually far more like an intaglio process and is not lithography.

By using a reasonably neutral substance like silicon, the production of the plate uses only water and not chemicals as with traditional printing plates. The unetched plate is passed through the processor and then through a plate washer that uses only water that can be recycled and used again.

By using substances like silicon, the production of the Presstek Zahara plate uses only water and not chemicals as with traditional printing plates

So, what is the catch? Just as Felix Wankel struggled with sealing a triangle shaped piston, waterless printing does require a rather narrow band of temperature in which to be functional. Water may be used to fight with the ink in wet lithography, but it also cools the plate very locally and this makes wet lithography easier than dry. Temperature control systems are essential for any press you are contemplating printing waterless on. Typically, temperatures need to be controlled to within 10°C so reasonably sophisticated chilling systems are needed. The key is to maintain the rheology of the ink to very finite levels.

The advantages

Back onto the benefits, the waterless process needs no chemicals, fount solution or cleaners. This can make significant enhancements to a company’s green credentials. Park Lane Press claims since becoming waterless they have dramatically reduced our water usage by approximately 70,000 litres a year. Being one of the first companies to pioneer the process and make it main stream, since 1999 they must have one of the lowest water bills in the printing industry. They also claim their waterless presses have also eliminated the need for IPA or special alcohol substitutes, meaning they reduced VOCs released into the atmosphere by 95 percent.

The waterless process needs no chemicals, fount solution or cleaners

Presstek also claims that, not only does the process tick lots of green boxes, it also can produce sharper images of higher resolution—as you are only using one printing substance. If you think about the emulsion of the ink and water, it is not surprising the dots can bleed and increase in size. In the waterless process, on the rheology of the ink changes the dot size.

Its industry leader product is called Zahara and it can be used over a wide range of products and not just traditional printing sectors. They have successfully deployed the Zahara plate system into the credit and security card sector, using it to produce all sorts of products such as ID documents and licences—as it is able to print on laminated plastics. In this sector, any number of press manufacturers can adopt their plates on presses such as the KBA Genius 52, Komori Lithrone, Heidelberg Speedmaster XL75 and others.

KBA has been an adopter of Presstek waterless printing plate technology for its Genius 52 press

The Zahara plate range can also be used for narrow width web offset printing. Label printing on presses such as Codimag Viva 340/420, Aniflo and Sanyo presses have been used for waterless printing. If you think this technology is only used for lower speed niche markets then think again, as Presstek also has a Zahara plate that can be used in newspaper production on presses such as the KBA Cortina.

Presstek have a Zahara plate that can be used in newspaper production on presses such as the KBA Cortina

Obviously if you are looking to convert to waterless printing, there needs to be more than a silicon covered plate to be considered. Presstek Zahara plate systems use standard RIP imaging devices alongside the Presstek Dimension Pro-W thermal CTP imager. Alongside the CTP device Presstek will also need to install the Zahara Eco-Kleen water-based plate processor, which comes with excellent eco-credentials.

Investment in waterless printing is higher than with standard wet offset and running costs can be a little higher, due to the inks being less mainstream, but the drivers to convert to a waterless system are many fold and a return on investment is very achievable. Building reputations is also important, as companies such as Park Lane have shown customers will pay for truly eco-friendly products at a very high level of quality.

Brian Sims Principal Consultant, Metis Print Consultancy, www.metis-uk.eu

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