Pressing matters

SBHD: The new generation digital superpresses are putting new demands on paper manufacturers to produce ranges that can cope, says Fay Sweet

“The current revolution in digital print technology is as radical as the move from letterpress to litho was.” So says Richard Allin-Jones, product manager of 4CC, a new state-of-the-art paper from Tervakoski.

The new stock is claimed to be the first designed solely with the latest print technology in mind. It is extremely smooth, offers sharp colour separation and realistic colour reproduction. Sample jobs, printed on 100gsm stock through the Fiery Color Server to the Ricoh NC5006 digital colour copier, are impressive. Colours are good and rich, flesh tones are accurate and detail is crisp. This isn’t coffee-table book quality, but it is far superior to every other colour copier I have seen.

Its characteristics, however, must be set in context with the demands of the latest print technology. Digital printing is quite unlike its traditional impact-based antecedents. At the low end of the scale, there is the colour photocopier, while at the top end are the latest superpresses – among them are the Xeikon DCP-1, Agfa’s Chromapress and Indigo’s E-Print 1000. Indigo has also just announced the launch of its Omnius One-Shot Color press designed for the label, packaging and decorative print sectors.

Essentially, while each press manufacturer had adopted a slightly different process, the technology shared by the new generation of digital superpresses is based on the electrostatic process. Instead of pressing ink on to the paper by means of a metal plate, the new machines charge the paper so that it attracts either tiny dry pigment particles (Xeikon and Agfa) or charged ink (Indigo) to form images. These particles are then heat-fused to fix them and make them stable. The process is extremely tough on paper, hence the need for specialist materials.

Among the greatest advantages offered by new direct digital presses is that they offer a fast screen-to-paper operation – most operate without the use, and additional time and expense, of either film or plates. Digitally stored designs are fed into the machine (thereby avoiding the potential degradation or corruption possible through film and plates) and are transformed into printed documents. Other advantages are customisation – documents can be tailored to their readers by changing whole chunks of text and/or illustrations during the course of the print run. And individual names can be printed on each document – extremely useful for direct mail applications, company brochures and so on. Last minute changes can be incorporated easily and short-run four-colour work, including trial runs of leaflets and brochures for proofing, market-testing and client approval, is now possible at a reasonable cost.

Like the photocopier, the latest presses have introduced new demands on papers. For best performance, stock must have excellent dimensional stability and high surface smoothness.

“Depending upon the make of the digital press, the paper will be subjected to high temperatures or pressures, or perhaps a combination of the two,” says Tony Galloni, marketing manager for graphic products at Sappi Europe.

Sappi is among the growing group of papermakers working closely with digital press manufacturers to develop papers suitable for the new machinery. Sappi’s Silken brand, originally developed to meet the high surface smoothness and dimensional stability requirements of laser colour copiers, is undergoing trials with one digital press manufacturer.

“The heat and pressure means the furnish [all the ingredients in a paper except wood] must be specially formulated and the papermaking process controlled to provide resistance to curling or wrinkling. Conventional printing and writing papers aren’t suitable. Another characteristic demanded is lack of dusting. This can affect the quality of the electro-photographic process and, as with less than ultra-smooth papers, lead to premature wear in precision components. The paper surface must be free of dust and chalk,” explains Galloni.

Among others at work on research and development is the merchant ISTD and the Kymmene mill. While the companies believe their laser-guaranteed papers will perform at their best on the digital presses, they are conducting tests.

“The main problem facing the paper industry is that there are few full installations in this country where it is possible to make tests,” says an ISTD spokesman. “But work is underway and results will be announced as soon as possible.”

Paper merchant Robert Horne has just seen the first of its brands – the mid-range coated Mondial Gloss – tested by Indigo. The smooth paper demonstrated fast ink-absorption and good ink fixing – both qualities demanded by the new digital presses.

MoDo merchants also has an eye on the digital market and has just announced it is exclusively handling Federal Tait’s high-tech Presentation range. This smooth stock has guarantees for non-impact printings with ink-jet, laser and copying and is typical of many papers that are sure to gain approval for use on the superpresses.

The launch of 4CC is sure to spur the market into ever-faster action. “The paper is an opaque wood-free which provides excellent running,” says Allin-Jones. “To achieve the ultra smoothness it is super calendered, which ensures extremely sharp colour separation and realistic reproduction without the mottling or curling effects found with ordinary paper. 4CC is also dimensionally stable, preventing distortion at high temperatures and the tightly controlled moisture content ensures an even toner adhesion to the surface.” The stock is available in weights from 100gsm to 190gsm.

Because the technology is new, there is still a great deal of experimentation improving presses and developing compatible paper stocks. Print quality is not yet on a par with offset – resolution is lower, and speeds are considerably slower. But improvements can be expected as the technology matures. The press manufacturers are working closely with papermakers to achieve the best possible printed results and most companies are developing lists of approved paper brands.

But before specifying paper grades, the best advice that can be given to designers is to check with the printer to discover what type of press is being used and, working on the assumption that the end product will be able to speak for itself, always ask to see printed samples.