Developments in Offset Printing

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Developments in Offset Printing
Jan 16th, 2009
Michael Jordan

Offset printing is the printing technique used all over the world - where the inked image is transferred from a plate to a rubber blanket and then retransferred to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique uses an image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a film of water. Offset printing has certain distinct advantages compared with other modes of printing such as - consistently sharp image quality, easy production of printing plates, longer life span of printing plate, because there is no direct contact between the plate and the printing surface, cost-effective as the more you print, the less you pay per page.

Offset printing is the most common form of high-volume commercial printing, due to advantages in quality and efficiency in high-volume jobs. Besides, many modern offset presses are using computer to plate systems as opposed to the earlier computer to films workflows, which further increases their quality of printing. More recently, flexography has become the most favored form of printing in packaging due to lower quality expectations and cheaper costs.

During the last decade and a half, offset printers have strived to effectively and efficiently combine the four basic parameters: quality, flexibility, productivity and environment. Printers are processing more and more four-color jobs and are also adapting to different qualities of paper. By this approach, printers and publishers are successfully satisfying customers’ changing needs and high quality expectations. In response to the emerging need to personalize newspapers and magazines runs are getting shorter and shorter. As a result, offset presses manufacturers have worked to reach shorter make-ready times. There have been remarkable developments of offset printing presses during the last 15 years. Manufacturers have increasingly automated their equipments and built machines to achieve faster output. Printers are under strong pressure from the European Community to eliminate pollution and switch over to environmentally-friendly processes. Compliance to environment regulations will become increasingly important as time passes.

Advancements in the computer to plate printing process have produced highly satisfying results. Improved print quality - laser graphics are first generation so there is no loss of resolution. Polymer plates made using film are second generation. In addition, because the computer to plate printing (CTP) process requires less consumables, CTP users are able to enjoy a number of cost saving benefits like - reduced plate usage (double-sided laser polymer plates can accommodate up to four images), elimination of film costs - image-setter or laser film, elimination of chemical costs - fixer, developer, and plate toner cartridges, elimination of supply shipping costs and hazardous material removal, elimination of maintenance contracts on processing equipment.

As regards savings in time and efficiency are concerned, computer to plate systems offer a number of benefits that include - improved plate throughput - it takes 3-5 minutes to etch a laser polymer plate against approximately 15 minutes for a polymer plate, full image and depth control give consistent plates every time, .reduced machine downtime due to avoidance of improperly made or damaged plates, not generating hazardous waste stream. There is much advancement in the computer to plate printing technology. When making a decision on the purchase of CTP equipment, one should be aware of the keys to the evaluation process: laser type, software capability, and system features.