The first aqueous (water-based) inkjet printer that can use white ink, the Epson Stylus Pro WT7900, is due to arrive on UK shores in the next couple of weeks. Announced back in September - and since then having been in beta testing with a number of large packaging companies for proofing - it is now ready for roll-out and, unlike the white stuff that's been blanketing much of the country over the past couple of weeks, Epson's white ink is a lot more predictable.
While white ink has been available for solvent and UV-cured inks for a few years, a water-based white is a big deal, particularly for packaging proofing. Water-based inks are the predominant technology for the proofing market due to their high quality and consistency, and because the inks are easy to handle and suitable to use in the studio environment where much proofing takes place.
"Our mission is to be a green company so we are obliged to come up with more environmentally friendly chemistries," says Epson Europe senior product manager for wide-format, Marco van Niekerk.
One of the big problems with white inks to date has been that the pigments tend to settle out of the ink, which means the solvent and UV machines using them have needed recirculation pumps to ensure the pigments remain in suspension. While this is fine for production machines, it is more difficult to justify the increased cost and complexity for a proofer. With its white ink, Epson has reduced this requirement for recirculation to shaking the white cartridge just once a week.
An optical illusion
To carry on with the snow analogy, Epson's new white ink is like a snowflake in another way; it's not actually white. The white effect is achieved by the scattering of light by clear hollow spheres. "It deceives the eye into seeing it as white," says van Niekerk.
Having tried to make a white ink for some time, the hollow sphere solution that Epson has ended up with is essentially the clear resin coating that surrounds coloured pigments in the UltraChrome inks, but without the pigment inside. Using hollow clear spheres does place some limits on the application of the white ink. "Because of the way the white works, you can only use it on films. If you print directly onto a light-absorbing surface, such as a board, the ink becomes invisible," van Niekerk explains.
For the core market that Epson has identified - packaging proofing where a white is needed ¬ the majority of jobs are onto clear or metallised films, where the white effect works fine. One thing to be aware of, however, is that applying pressure to the ink, such as running through a laminator, can crush the spheres, which again destroys the white effect.
How bright are your whites?
A couple of the issues with white inks are how opaque and bright they are. A low value means some machines may need to make multiple passes. Epson says it has formulated its ink to produce an acceptable result in only one pass. Van Niekerk explains that, as there are no standards for the density and opacity of the white, Epson measured a large number of packaging samples to derive a value that meets more than 90% of the market's requirements.
Being water-based, the ink needs coated media and Epson has launched a premium clear film for final proofs and a slightly milky one for less critical applications. It is also working on other media with a metallised film due in March, and self-adhesive and shrink films to follow.
The white ink can be applied before or after the process colours to allow a range of different effects to be created in the proof, with the functions controlled by the RIP/workflow used. As well as under- and over-printing with the white ink, the WT7900 can also apply it along with the other colours, which helps it to hit some Pantone colours.
Unlike most Epson printers, there is no driver, which means it must be driven by a supported workflow. "It makes sense as packaging firms will already have the right workflow," van Niekerk says. So far, Compose, EFI, EskoArtwork and GMG products can drive the machine, with others developing the ability. GMG's Flexoproof XG and Dotproof XG modules allow dot proofing from 1-bit ripped data.
Epson's WT7900, is similar in size to the 7900 on which it is based - a 610mm- or 24in-wide machine. "Our investigation of the market found that the majority of the output required an A2-sized device with some A1 and the need for a 44in-wide machine was so low we didn't think it was worthwhile, however, if we find there is a demand, it would be quite easy to implement," he says.
While you can't print white onto board, the WT7900 retains the CMYKOG inks of its
sister, with the light inks being swapped for the white, plus a cleaning fluid. This means that you can use it to produce proofs onto board, as long as they don't use white.
And, like the 7900, the WT also has the option of a built-in spectrophotometer for device calibration and proof verification. Despite this, van Niekerk cautions that although fine for reflective jobs, it is "more difficult on transparent film".
"It's really intended as an option for companies doing a mix of film and board work. If the software supports it, you can use it, but the results aren't as good as when working with reflective media," he adds.
Reduced running costs
With flexible packaging identified as the sweet spot for the machine, Epson is focusing its efforts in this sector, and van Niekerk argues that, following the initial launch and subsequent tests, there is plenty of demand here to keep the group busy. Epson also acknowledges that the ability to print white onto transparent substrates has other applications, including graphics, and as such it is eagerly waiting to see what other applications printers want to try.
Epson claims the machine triumphs with its running cost, where using its premium clear film and the white ink, it calculates that an A2 proof costs €12 (£10.55), which it says compares to €60 (£52.75) for an equivalent proof produced on Kodak's Approval - in its words, its biggest competitor.
"It's one-fifth of the price per proof and it's cheaper to buy," he says, of the machine, which costs £6,995 (without RIP). As for other alternatives, there are eco-solvent and UV-cured machines from Mimaki and Roland DG that offer white inks. The UV-cured machines offer a further benefit, in that in addition to white, they offer a clear varnish that can be used to replicate coating effects and relief applications, such as for Braille on pharmaceutical packaging and embossing for entertainment packaging. All these machines use a true white pigment that works on boards and film.
Ultimately, the choice of which machine is right for comes down to applications. Of course, there are instances where the white feature can't be used on the WT7900, but despite that, it is a competent proofer covering most bases.
SPECIFICATIONS
Max speed
40m2/hr
Max width
610mm
Resolution
2,880dpi
Price
£6,995
Price per proof
€12 (£10.55) per A2, including Epson premium clear film
Contact
Epson UK 0871 222 6702
www.epson.co.uk
THE ALTERNATIVES
Kodak Approval XP4
A venerable digital halftone proofing system that includes metallic and white inks. It needs a laminator to transfer onto final stock, but it supports pretty much any substrate. It produces actual dots on actual stock and you can also choose the lay-down order. It's not particularly fast or cheap, but short of a machine proof, it's still the closest predictor you'll get.
Max speed 1.4m2/hour
Max sheet size 676x530mm
Price €45,000 (£39,550), including laminator and Kodak Proofing RIP
Contact Kodak UK 020 8424 6514 http://graphics1.kodak.com/
Mimaki CJV30-60
A solvent machine, with white, the CJV30-60's price makes it an option for proofing and short-run production. It is available in 1m, 1.3m and 1.6m versions. Mimaki also offers UV-cured machines, with the £100,000 UV-cured UJF-605R11, designed specifically for proofing flexo and gravure, and the £40,000 hybrid UJV-160 -both offering white ink.
Max speed 12m2/hr
Max width 610mm
Price £7,995
Contact Hybrid Services 01270 501900 www.hybridservices.co.uk
Roland VersaUV LEC-330
Suitable for the production of packaging mock-ups, labels and decals, the VersaUV uses CMYK and white inks with a varnish to create gloss or matte spot UV varnish and embossing, doming and Braille effects. The LEC-330 uses Roland's integrated print and cut technology to print onto a range of substrates including litho stock, metallic board and uncoated clear film. It can handle substrates up to 1.3mm thick and can also perform cutting and creasing. An A2 CMYK+W colour proof costs 91p, excluding stock.
Max speed 8m²/hr
Max width 760mm
Price £36,999
Contact Roland DG UK 0845 230 9060 www.rolanddg.co.uk
