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January 2010 — Documented evidence suggests that what was later to be known as gravure printing was first practiced as a craft as long ago as 100AD in China. Many centuries passed with the process largely unchanged, images were produced using a simple engraving tool. It wasn’t until the 16th century that chemical etching was introduced, which made it possible for an image to be scratched onto a coating on the metal surface of a plate and then engraved using an acid – a procedure with far reaching consequences. By 1838 the principal of photography was becoming more widely understood and some entrepreneurs began to realize commercial possibilities.
Although it certainly did not occur overnight print producers began to try to find ways to try to reproduce direct images in a fast and accurate manner using the rotogravure or intaglio process. In 1875 gravure had advanced sufficiently and print technologists were able to duplicate photographic films by using gelatin, which hardened when exposed to light. Unhardened areas were then washed away and etched using acid.
Rotogravure took root first in Europe with the development of presses by companies such as the Anglo-German Reich-Wood Company in 1903, then in the United States around 1918 where the process became very popular with the newspaper industry.
Up until recently gravure was the mainstream print process that most closely resembled photography. Gravure applies the ink in controlled doses from different sized cells that have either been chemically etched or electronically engraved into the surface of the printing image, commonly a copper coated cylinder. These cells can be variable in size, shape and depth; the smaller the cell volume the lighter the resulting visible tone; conversely the larger the cell volume, the darker the apparent tone.
Tom Kerchiss of colour communication systems and print/coat technologies says that for work that demanded the highest quality such as high volume fashion magazines or long run premium flexible packaging, gravure was generally regarded as the print process of choice. This was certainly the case during the 1960’s and 1970’s, gravure being ahead of processes such as flexo for both quality and performance. Arguably a reversal of fortune didn’t occur until the late 1980’s.
“There are many reasons why print practitioners and customers began to take flexo more seriously. One of these was the drive towards reducing solvents in printing plants. Flexography was better able to reduce the reliance of solvent products through the development of water-based inks and through the use of UV technologies”.
Continuing, Tom Kerchiss remarks: “ Gravure on the other hand had a more difficult time in making the transition to water-based materials. Another reason for flexo’s growth was the economics involved in meeting short run product demands. New marketing conditions, frequent brand package changes, short-term sales offer and product introductions favoured flexo as more cost efficient for short runs than gravure. However, gravure press manufacturers and other technologist didn’t let flexo have it all its own way. Press and consumable producers have made serious attempts to reduce the cost equation difference”.
Higher press speeds and low waste are amongst the benefits of gravure. The process is also simple to execute and once a gravure press is up and running there is theoretically little to go wrong. Gravure’s reputation for reliability and ease of operation has helped make it one of the favoured print processes in countries with a relatively low skill base. So what else is in gravure’s favour? Well it can achieve quality levels unmatched by other processes, particularly on cheap or poor quality paper. Furthermore, in today’s environmentally conscious environment, gravure does not require the same high levels of energy output as other processes.
RK Print Coat Instruments Tom Kerchiss believes that there will continue to be a market for both the flexo and gravure process. Gravure gives a greater level of design repeatability, as it is theoretically simply with fewer components than flexo and fewer variables. However, in terms of quality technical advances in flexography have narrowed the quality gap.
For value-added work, inline gravure operations are well suited to gravure. Cold seal, PvdC, varnishing, laminating and sheeting can all be done on many top of the range machines. Developments in laser technology for engraving cylinders have speeded up cell production, shortening downtime in the process.
Regardless of the merits or de-merits of each print process, all print producers need to maintain consistency of quality with colour accuracy a critical element. Equally important, especially given today’s harsh trading conditions is the need to control operating costs and to get the most from the machine and the workforce. Control of process variables or print inconsistencies has become paramount.
Gravure printers benefit from devices such as the Printing Proofer from RK Print Coat Instruments, which enables users to bring process variables under control so that print consistency remains at its highest level and on-press waste is kept to the minimum. An additional advantage of the Printing Proofer is its multi-tasking capability. “ Its not just the gravure printer that can take advantage of the Printing Proofer,” says Tom Kerchiss.
Many print houses, notably producers of flexible packaging have multi-print process facilities, sometimes running gravure, sometimes running flexo, depending on the dictates of the job.
The Printing Proofer produces high quality proofs in an instant using gravure, gravure-offset or flexo inks. Featuring electronically engraved printing plates, the Printing Proofer is designed so that two or more inks may be printed simultaneously for comparison purposes, and registration is included for overprinting. Interchangeable print heads make this a highly versatile system. Furthermore, wet and dry laminated samples can be produced on the machine once the gravure head is fitted together with RK’s own K-Lam laminating accessories.
Print process selection depends upon many factors. “One thing is certain though, our customers are astute and whether the process is gravure or flexo, or something else, colour communication tools such as the Printing Proofer, FlexiProof or UV Paste Ink Proofer – the tools are at hand to keep print productivity productive and accurate,” concludes Tom Kerchiss.
For further information email sales@rkprint.com, www.rkprint.com
Source: RK Print Press Release
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