Ink is the enabler, says Paul Casey in the context of UV printing: “It can be used to differentiate a printer without high capital costs”.

One of two supplier representatives to discuss the subject at SWUG, he’s the one from ink maker Sun Chemical, of which he is European coldset product director. The other is Pat Keogh (pictured left) who, as global sales director of Baldwin UV and Primarc, can talk authoritively about reflector and curing systems and is hoping his company may score its first newspaper installation in Australia.

Keogh also sees UV as a tool for publishers to use in meeting the challenges caused by falling circulations and advertising revenue, and increased demands from environmental legislation.

While heatset equipment is expensive to install and maintain, requires VOC permits, and has high costs in gas and paper waste, what he called ‘coldset UV’ was cheaper and smaller, with no VOCs and a lower energy requirement.

It does however, involve the use of inks which are substantially more expensive, even though ‘mileage’ is greater. Later, Casey says UV inks are typically three times the price of coldset and heatset inks, with black similar in price to colours. “We’d expect an increase of 10-15 per cent in mileage, but because it’s a premium product, higher densities are typical,” he says.

The explanation is that in UV, 100 per cent ink solids remain on the sheet, whereas heatset inks – in which up to 40 per cent is solvent – are reduced during drying.

Keogh says advantages of UV printing – which inks in which a chemical curing process is initiated by exposure of UV light – include:

• excellent rub and chemical resistance;

• no dot gain or bleed through;

• no ink tracking, blistering, or set-off on rollers, belts, folders and other equipment.

Because of the high water-holdout of UV inks, the choice of fount solution is critical, and Keogh recommends that it should be mildly acidic… and CTP plates “tend to work better,” he says. EPDM rollers are best, although vinyl nitrile is the preferred composition when switching between UV and conventional inks.

Keogh says the design of lamp units is critical – “anyone with a very cool lamp hasn’t turned it on,” he says – with 52 per cent of energy typically emitted as heat and only 28 per cent UV. And while ozone is a byproduct, it returns to oxygen after venting.

The latest, computer-designed systems consume less energy and allow higher production speeds. Dichroic reflector coatings maximise UV output while minimising heat reflection, and shutters close whenever the press stops.

Keogh says the Baldwin subsidiary has yet to apply its technology to newspaper production, “but it’s very straightforward compared to other markets in which we are involved,” he says.

And the health concerns of the 1970s are largely a thing of the past: “Solvents used for wash-ups then gave it a bad reputation, but those used today are less aggressive,” he says. “Inks do need care, however, and we recommend the use of gloves.”

Although most curing is currently UV, Casey suggests that the future may be with EB (electron beam) curing, which offers similar advantages without requiring photo-initiators, which are responsible for the skin sensitivity.

And on ink costs, he says demand for acrylates – also used in the manufacture of disposable nappies, for which China is a large emerging market – is a driver.

• SWUG Australia report from GXpress May/June 2011