The Printed Word, Part 2
As we mentioned in last month’s topic, printing has evolved quite a bit since the days of Gutenberg. In Part 1 of this article, we concentrated on the various methods for creating the artwork to be printed — pre-press. This month we’ll discuss some of the more common printing processes.

What a relief
The earliest forms of printing were relief printing — where ink is transferred by means of a raised printing surface. If you ever did wood block prints in art class, you’ve done relief printing. Over a thousand years ago the Chinese used this method, also called block printing. The non-printing areas of a block are carved away from the surface of a piece of wood, leaving the characters and designs in relief. Ink is “painted” onto the raised surface, then a sheet of paper is place on top. The image is transferred by rubbing the back of the sheet.

Letterpress printing uses the same concept. This is how Gutenberg printed pages. In letterpress printing, raised type forms are combined to make a printing plate. The paper is laid on top of the inked plate and the “press” applies pressure to transfer the image. Letterpress printing has mostly fallen from favor, although there are still some ardent fans of this form of printing. It’s estimated that less than five percent of the printing done in the United States still uses this antique printing process.

And they’re off
One of the most common forms of printing today is offset lithography. Its origins can be found in 1798, when the German Alois Senefelder experimented with grease and water. He drew a design on a stone using a greasy crayon, then dampened the stone with water. He found the water only clung to the parts not covered by the crayon design. Then he inked the stone with a greasy ink, discovering the ink would only cling to the design itself. Senefelder pressed a piece of paper against the stone, transferring the ink (in the same form as the design) to the paper. This technology, naturally, has improved drastically over the years, but the principle remains the same.

In modern offset printing, metal, plastic or paper plates have replaced stone. Images are photographically placed on the plate, then transferred to a rubber cylinder, which then offsets the image onto the final printed piece. In other words, a forward-reading image is transferred to the cylinder where it becomes a backward-reading image. Then when it’s transferred again to the final material, it’s forward-reading once again. Offset printing gets its name from this double “offsetting” of the image.

Time for recess
Instead of the raised image used in letterpress work, gravure printing is done from a recessed, or engraved image. This process, also known as intaglio, is often used when extremely high quality printing is required, or for working with specialty materials such as foils, plastics and other mediums with little or no absorptivity. For instance, fancy invitations are usually printed this way.

The typical gravure plate is a large copper cylinder upon which the image is etched or engraved. Ink is applied to the cylinder, fills these crevices and adheres to the surface. A blade of hard rubber or plastic is used to scrape the ink from the non-image areas before the paper comes in contact with the cylinder. The speed at which the paper moves provides suction, pulling the ink from the crevices onto the paper. As there’s no offsetting of the image, the cylinder must be engraved with a negative version of what’s to be printed.

Thanks
Imagine, for just a moment, what life would be like without the printed word. Would society be anywhere near as advanced as we are today? Not likely.

So the next time you curl up with a good book, peruse a magazine, or flip through a newspaper, say a silent “thanks” to Johannes Gutenberg for his life-changing invention — the printing press.