Home | Contact Us

Print and Finishing

Digital printing is a term often misunderstood and used to generalise what is a diverse range of output devices. Your desktop inkjet is a digital printer. For ease of definition a digital printer can be considered as any device that has the ability to change, 100%, the content from sheet to sheet without stopping.

HP Indigo 5000

Digital Printing is different to analogue or conventional methods but some similarities remain. The Hewlett Packard 5000 7 colour digital press, like conventional presses uses liquid ink to print an image. The major difference here however is that it uses ElectroInk technology, to enable the ink to be directed electrically using charged particles in the ink. This press uses a light sensitive plate that will attract ink. However unlike conventional printing that uses a fixed or etched plate that cannot change, the HP 5000 uses a photo imaging plate, a dynamic light sensitive plate that can be re-imaged with different information on every revolution of the cylinder. The ink is attracted to the photo imaging plate by an electrical charge rather than a physical transfer from ink duct to cylinder.

Blanket transfering
Likewise it is then attracted from the photo imaging plate to the blanket. This has a number of advantages including the elimination of the incomplete transfer of ink that is a characteristic of conventional offset litho. HP Indigo press technology uses a blanket to transfer the ink as in conventional offset printing. The blanket acts as a shock absorber and pressure pad to ensure even ink transfer to the substrate. This enables the press to use a wide range of substrates of different surface and thickness, just like conventional printing.

The difference is that unlike conventional offset printing the HP Indigo blanket transfers 100% of the ink to the substrate. The total transfer of ink from the blanket allows the same set of cylinders to be used to print all colours ensuring precise colour to colour registration and colour consistency throughout.

Colour switching
An entire new separation, in a different colour can be created for every rotation of the cylinder. This is called on the fly colour switching and is the technology that allows this press to print fully collated duplexed and individually personalised sheets.

It is this process that allows what is known as personalisation or versioning, where in conjunction with a database we can make every copy unique with any element of the supplied information whether its text, images or a combination of all of these elements and all in full colour.

Colour mixing
The special liquid ink technology now offers the unique opportunity, in digital printing, of mixing special colour inks in the same way as offset litho, giving that extra authenticity to brand colours where required. The range of premixed colours now extends to 97% of the pantone library and we can also have custom inks formulated made to match your specific swatch or for printing onto a specific substrate.

Xerox

The other main digital colour press technology is the xerographic (dry toner) process, commonly found in laser printers and colour copiers. This process is typically characterised by a very different type of print quality. Dry toner particles are between 7 to 9 microns in size and struggle to reproduce fine detail and acceptable colours. With dry toners it is difficult to match the surface gloss of a substrate, usually giving the image a glossy appearance on a matt paper and an ultra-glossy appearance on a glossy paper. The process also attracts a lot of static that is transferred to the paper and can cause significant problems and wastage in the finishing process.

This is compensated by factors such as ease of use with very little operator intervention and suitability for clean operation within an office type environment. Our Xerox equipment efficiently produces a wide range of reports, manuals, full colour personalised mailing material, utilising its full duplexing and collation capabilities in conjunction with powerful Creo RIP technology giving outstanding colour quality.

Print and Finishing

© 2007 Summerhall

Summerhall | Services | Solutions | Site Map