Printing, it’s all around us no matter where you look! We use it in our day to day lives whether we notice it or not. Printing is on your coffee table; in your fridge; on the bumper of your car. It can be found on your walls, on your clothes, and on your coffee cup. It’s on your mail, in your wallet, and most often you are holding it right now.
Print, from the Old French preinte 'pressed,' feminine past participle of preindre, from Latin premere 'to press’, it has been with us for a long time dating back to around the 3rd century in China using Woodblock printing techniques. By AD 593, the first printing press was invented and the first printed newspaper was available in Beijing in AD 713. Since then, movable type printing was invented in the 11th century allowing a much more flexible process than hand copying or block printing. Although this new type of printing made the process a lot faster, it was prone to breaking easily as the type was made of clay or wood, thus it still remained just a faster version of woodblock printing.
In the 15th century, Johannes Guttenberg invented a new kind of movable printing using type pieces made from an alloy of lead, tin and antimony, which are the same components used today. This new more durable kind of printing meant the lettering was more uniform and sturdier, which lead to typography and fonts.
It wasn’t until another 400 years later a breakthrough in printing was invented, the rotary printing press. In the 19th century, Richard March Hoe used impressions curved around a cylinder to print continuous rolls of paper. This sped up the printing process and allowed large volume printing to be produced. Later the design was improved and is still used to this date.
Printing is generally grouped into the following categories:
Letterpress (Relief) printing:
The original, mechanical Gutenberg printing process where movable type in a reversed raised surface is inked and then pressed into a sheet of paper to result in a positive right-reading image. This was mainly used for books from the 15th Century to the 19th century. This process also includes the direct impression of inked printmaking blocks such as photo-etched zinc plates, linoleum blocks, wood engravings, etc using the press method.
Flexography:
A relief process used for special purposes such as packaging. An updated version of the letterpress, flexography uses a flexible relief plate to print on to almost any type of non-porous surface including plastic, metallic films and cellophane. It is widely used in food packaging and is suited for printing large areas of solid colour.
Gravure (Intaglio):
A more expensive process which produces higher quality colour than letterpress. Images are etched onto a metal plate and filled with ink and then placed on a rotating cylinder. The ink flows into the etching and the excess is wiped off. As the cylinder rotates, the paper is pressed under a heavy pressure against the plate on the cylinder, thus transferring the ink onto the paper with the surface slightly raised and the back indented. The etching is engraved with tools or chemicals.
Photo Offset Lithography:
A chemical method of ink transferal and the primary major printing process today. First, an image is transferred photographically to a thin metal, paper, or plastic printing plate. The image is not recessed or raised like other forms of printing, instead, it is at the same level as the plate. The plate is wrapped around the plate cylinder of the printing press and rollers apply oil-based ink and water to it. Since oil and water do not mix, the oil-based ink will not adhere to the non image areas, which absorb the water. The ink then only sticks to the image area on the plate and is transferred to a rubber blanket (cylinder) that then transfers the image onto the paper as it passes through the machines rollers. Due to the fact the image isn’t directly printed from the plate to the paper, this is where we get the term ‘offset’.
Screen Printing:
A very flexible process used extensively in specialty printing and advertising and can be printed onto a wide variety of surfaces such as paper, board, plastics, glass, metals, fabrics. The process uses a mesh stretched over a wood or metal frame. An image, as a stencil, is transferred onto the mesh either by hand or photochemically. The frame is then placed over the material to be printed on and a thick paint-like ink is applied to the top of the mesh screen. Using a squeegee that is drawn across the screen, the ink is forced through the fine mesh openings only where the template has been placed, thus forming an image on the material. The thread count and the diameter of each thread determines the amount of ink that is deposited onto the material.
Xerography:
An electrostatic method of image transfer onto smooth paper as in the Xerox photocopier. This form of printing is when the image is transferred by using electric charges. When the beams of light, usually from a laser, strike the original material, such as a white page with black lettering, the rays are reflected off the white areas onto a photosensitive plate over which electric charges have been spread. The charges are then neutralized only on the areas struck by the light reflecting off the blank areas. Since no light rays are reflected form th darker areas such as the text, charges are retained on the plate corresponding to the lettering on the original. Toner, a plastic powder, is then applied that sticks to the charged areas. A sheet of paper is then passed between the plate and another charged object that draws the powder from the plate onto the paper. This forms an image of the original. Using heat, the powder is then fused to the paper to produce a perfect copy of the original. Variants in size can be produced because the image is projected rather than directly contacting the plate. A laser printer uses a similar process where data sent from a computer is used to turn a laser beam on and off rapidly as it scans a charged drum.
Ink Jet Printing:
Printing by small jets propelling droplets of ink onto paper. This form of printing uses print cartridges with a series of electrically heated chambers. The printer runs a pulse of current through the heating elements causing a steam explosion in the chamber to form a bubble. These bubbles propel droplets of ink onto the paper, hence the name by Cannon, ‘Bubble Jet’. The surface tension of the ink along with the condensation, contracts the vapor bubble and pulls a further charge of ink into the chamber through a narrow channel attached to an ink reservoir. The ink is water-based using pigments or dyes and is known as ‘aqueous’.
Engraving:
A process of incising a design onto a hard flat surface then transferred to paper, used for fine stationery printing and bank notes. Normally using copper or zinc plates, incisions are created by etching onto the plate either by hand or machine. Ink is then applied to the plate and rubbed with a tarlatan cloth to remove the excess ink. A damp piece of paper is placed on top and the plate and paper are run through a printing press. Through the pressure of the press, the ink from the recesses on the plate is transferred to the paper. Due to the high microscopic detail that can be obtained in this process, bank notes, checks, bonds and other security sensitive papers are printed using this style.
Thermography:
Printing that produces raised printing, used in stationery. Using most printing processes, a special powdered polymer is applied to the wet ink areas on the sheet as it comes off the printing press. A special ink is used which contain no dryers or hardeners so that the ink remains wet when it comes off the press. The excess powder is vacuumed from the non-image surface and dry ink areas. The sheet is then passed through a radiant oven system and is exposed to temperatures from 500 to 900 degrees Celsius for around 3 seconds. The heat from the oven reacts with the powder and starts to rise, which is called ‘filming’. Once the sheet exits the oven, it is placed in a convection cooling system where the reaction is stopped and thus forming a raised image. This process is also used to print Braille text.
Whether we use digital output or traditional presses, printing is ever evolving and changing the world we see. With the introduction of the internet and more and more people sending electronic mail and communications, The printing need seems to be declining in the past few years, but like myself, a lot of people still prefer to feel the grain of the paper as we turn the page of a novel we are reading. So I believe printing will still be around for many years to come whether it is those beautiful wedding invitations we receive in the mail or those replicas of the worlds masterpieces hanging on our walls.