CTP

The changing market place in plate consumables

The news that Agfa Graphics is to limit its analogue plate production to just one negative-working and one positive-working product will come as no surprise when you consider that in Britain and Ireland the uptake of CTP now means that nine out of ten plates consumed are for digital use. Whilst the rate of CTP uptake has been faster and more intense here, the rest of the world is following suite and most of Europe is 75% digital whilst in the USA the figure is about 65%.

Just a few years ago each plate manufacturer had three or four plates for various applications in both negative and positive analogue technologies but now the picture has changed considerably with different laser types and various plate technologies contributing to an almost confusing array of products. Added to this some printers still have a need for plates dedicated to their particular application - heatset, newspaper, UV, bakeable etc. - whilst others might want to go green or relocate platemaking from a wet area into the office. It is easy to see why manufacturers are dedicating so much R&D resource to new digital products as witnessed at IPEX 2006.

At the Birmingham show Agfa announced no less than three new (processed) thermal plates, added a third product to its range of processless thermal plates and even demonstrated a visible light processless plate for release in 2008 which means that violet laser users can now be assured of a processless upgrade path previously the domain of thermal users. What does this ever widening choice of products mean for the average printer trying to decide which plate or platesetter is best for him? Irish Printer asked Mike Loose, Agfa Graphics Plate Product Manager for Europe North to explain.

Thermal or visible light, processed or processless?

With analogue platemaking there was a simple decision between negative or positive working then a choice of plates based on your application e.g. standard for run of the mill work, FM for high resolution, high speed for step and repeat, solvent resistant for UV work and so forth. Now there is still that same application-led choice but additionally you will have to decide which laser system to opt for whether buying new, second-hand or replacement. Currently the market is split fairly evenly between thermal and visible light and the latter is divided between three different laser wavelengths however for the future only violet diodes will be supplied therefore both red and green (FD YAG) lasers are now restricted to the second-hand market.

Violet lasers are very efficient, offer low cost of entry and until recently violet devises were always faster than thermal therefore more productive. Thermal delivers marginally higher resolution and can generally match violet for productivity but is more expensive. Traditionally thermal offered the only route to processless platemaking however both Agfa and Fuji recently announced they would launch processless violet plates around 2008 so this is no longer the case.

Visible light plates are available in two types, silver or photopolymer. Each type requires a different processor and as the name suggests need to be used in controlled lighting conditions although many modern platesetters have daylight loading facilities. Silver plates are available for red, green and violet laser applications and are favoured by the small to medium printer because of the small developer bath size. Photopolymer plates are available for green and violet lasers, have slightly less resolution than silver or thermal but are longer running which finds favour for newspaper and some commercial printer applications. Processing can be marginally more expensive for the small printer and is more complex requiring a pre-wash and pre-heat section. Depending on press and paper conditions the run length of silver plates is up to 350,000 and photopolymer up to 450,000. Generally photopolymer plates are both UV capable and bakeable as well.

Standard thermal plates offer the highest resolution but have a comparatively short run length of up to 150,000, poor solvent resistance and no UV capability however are bakeable to enhance run length. Most manufacturers have now introduced premium products designed to give longer run length and solvent resistance without the need to bake. Like photopolymer, thermal plate processing can be expensive for the smaller user because of the need to change the large chemistry bath according to time and/or throughput which means the printer does not always get value from the bath if throughput has been low.

Processing costs, processor maintenance, waste costs and the desire to bring platemaking into cleaner areas of the factory have all combined to make processless platemaking a popular choice for the future. There are now four manufacturers offering processless thermal plates and although early products had poor run length all are now capable of a respectable 100,000 impressions and at least one plate will run 200,000, is suitable for solvent and UV conditions and is bakeable. The image on a processless plate is fully formed during exposure by the laser thus obviating the need for development however the unused coating still has to be removed. This is achieved either on-press via the ink train or off-press in a simple gumming unit which is the most popular system to date. One product even works through a conventional processor with a low maintenance wash-off solution replacing the developer. More a case of processed-less than processless perhaps.

In eliminating development the processless plate offers obvious cost savings on chemistry and equipment but there is much more. Processless platemaking will deliver hidden savings on maintenance time, filter costs, waste care provision, wash water costs, will save space and has the intangible benefit of eliminating a quality variable - there is one less process to go wrong. Last but by no means least, it is environmentally sound and this will appeal to many printers seeking green credentials, not only through ISO accreditation, but when marketing themselves to blue chip companies who increasingly like to appear green or be carbon neutral.