The common method of printing books nowadays is called ‘offset printing’ (often ‘offset lithography’). Text and images are transferred to metal plates via photo emulsion. These plates are then fixed to a cylinder on a printing press. Water is applied, using dampening rollers, and it covers the blank areas of the plate, but not the image areas, because the emulsion repels water. Special ink, which is repelled by water, is then applied and this adheres only to the image areas. This ink is then ‘offset’ onto rubber blankets or rollers, which conform to the paper surface and transfer ink with a uniform pressure, creating sharp, clean images.
Digital printing, a method that is becoming increasingly popular for large print runs, is favoured because it is less labour-intensive and does not require the use of printing plates, which need replacing. Ink jet or laser printers transfer toner or pigment onto the paper surface—a process that is fast, but not to the standard of other methods, as it adheres only superficially and loses some fine image detail.
I have explained the letterpress printing method in my previous blog, ‘About Letterpress Printing’, so you know the process—but perhaps not the characteristics that define it. There are two contrary yet coexistent qualities that distinguish something that is letterpress printed from something printed through offset or digital. These are: sharpness and irregularity. The text has a crispness that is more immediate to the eye than other methods, which is the result of the direct contact of metal on paper.
Sometimes this contact is so sharp that it produces a bite, or indentation, in the page. To the professionals who were once well-established in the trade, ‘the bite’ was considered shoddy workmanship; the type must just ‘kiss’ the paper; however today among many circles it’s considered the signature of letterpress.
The other quality, irregularity, is revealed in the slight difference of each character. This has largely to do with variations in ink coverage, but also the wear on the type itself and the evenness (or lack of evenness) in the impression.
These incidentals give letterpress printed material an elegant, tactile quality, which is strikingly unique in our age of the digital word and mass-produced text.
Offset Printing Technology: http://www.offsetprintingtechnology.com/sub-categories/offset-lithography/
Digital Print Preservation Portal: http://www.dp3project.org/technologies/digital-printing/inkjet