Etching - Etching
is the process of using strong acid or mordant to cut into the unprotected
parts of a metal surface to create a design in intaglio in the metal (the
original process—in modern manufacturing other chemicals may be used on other
types of material). As an intaglio method of printmaking it is, along with
engraving, the most important technique for old master prints, and remains
widely used today. Instead of carving an image into the metal
which could leave rough edges etc a strong acid is used to create an image. (Wikipedia – 27th
Sep 2010 Online)
Intaglio printing: a printing process that uses an
etched or engraved plate; the plate is smeared with ink and wiped clean, and
then the ink left in the recesses makes the print. Basically an image is carved into the block
almost like a template. The template is then filled with excess ink while the
rest of the ink is wiped off. This can then be used like a stamp to create an
intaglio print. (Online Dictionary – 27th Sep 2010 Online)
Linocut – Is a relief print produced in a
manner similar to woodcut. The lino block consists of a thin layer of linoleum
(a canvas backing coated with a preparation of solidified linseed oil) usually
mounted on wood. The soft linoleum can be cut away more easily than a
wood-block and in any direction (no grain) to produce a raised surface that can
be inked and printed. Its slightly textured surface accepts ink evenly.
Linoleum was invented in the nineteenth century as a floor covering; it became
popular with artists and amateurs for printmaking in the twentieth century. Instead
of carving into the lino similar to other methods this involves carving around
the image creating a raised image in the lino which will then be covered in ink
or paint and pressed against another surface to create an image. (www.tate.org
27th Sep 2010 Online)
Screen
Print - Screen
printing or silk screening is a printing technique particularly suited for flat
or relatively flat surfaces. The heart of the process involves a fine mesh or
screen that is tightly stretched around a rigid frame. The areas that are not
to be printed are masked out on the screen. To create the print, the framed
screen is positioned over the item to be printed along with a dollop of thick
ink. A squeegee is then used to press the ink through the screen. The masked
areas prevent ink from passing through, but the unmasked areas allow the
ink to be imprinted on the material. The final step is to send the item on a
conveyor belt through a heat-tunnel. Screen
printing involves taking a piece of mesh which can be made from steel, nylon or
polyester. They even used to use human hair. Areas are then block off to form a
non permeable material which means that it will not allow the ink or paint
through, thus forming a stencil type device. The ink will then appear in the
open spaces. The stencil is then laid onto a material such as paper or fabric
and a roller is then used to push the ink into the open spaces forming an
image. (www.wisegeek.com 27th Sep 2010 Online)
Woodcut - Woodcut—formally known as xylography—is a relief printing artistic technique in printmaking
in which an image is carved into the surface of a block of wood, with the
printing parts remaining level with the surface while the non-printing parts
are removed, typically with gouges. The areas to show 'white' are cut away with
a knife or chisel, leaving the characters or image to show in 'black' at the
original surface level.
The surface is covered with ink by
rolling over the surface with an ink-covered roller (brayer), leaving ink upon
the flat surface but not in the non-printing areas.
Multiple colours can be printed by
keying the paper to a frame around the woodblocks (where a different block is
used for each colour. Woodcut is similar to linocut. Instead of
carving the image into the surface and filling the gaps with ink, you cut in a
way that the image is still level with the surface of the block. This is then
inked or painted and pressed down to create a print. (Wikipedia
Article 27th Sep 2010 Online)
Lithography
- Lithography
refers to a lithograph print that is made from an image which has been applied
to a flat surface. Traditionally this flat surface was a specially prepared
lime stone, but today grained aluminium-printing plates and the original stones
are used. The process is based on the fact that oil repels water. An image is
drawn, painted or photographically applied the stone or plate using a greasy
medium. The image will repel water and accept ink. Lithographic inks are oil
based.
The plate is placed on a
special press and is then rolled up with either leather or rubber rollers.
Paper is then placed on the print and is run through the press by hand. Like many
other printing processes one colour at a time is printed.
The
flat surface of the plate or stone is slightly roughened, or etched, and
divided into hydrophilic regions that accept a film of water and thereby repel
the greasy ink, and hydrophobic regions that repel water and accept ink because
the surface tension is higher on the greasier image area which remains dry. The
image may be printed directly from the stone or plate. This process is
different from gravure or intaglio printing where a plate is engraved, etched
or stippled to make cavities to contain the printing ink and in woodblock
printing and letterpress where ink is applied to the raised surfaces of letters
or images. (www.artprintsa.com/lithography
27th Sep 2010 Online)
The
second type of printing:
Mechanical
Printing
Letterpress
- Letterpress
printing
is a term for the relief printing of text and image using a press with a
"type-high bed" printing press and movable type, in which a reversed,
raised surface is inked and then pressed into a sheet of paper to obtain a
positive right-reading image. It was the normal form of printing text from its
invention by Johannes Gutenberg in the mid-15th century until the 19th century
and remained in wide use for books and other uses until the second half of the
20th century. In addition to the direct impression of inked movable type onto
paper or another receptive surface, the term Letterpress can also refer to the
direct impression of inked printmaking blocks such as photo-etched zinc
"cuts" (plates), linoleum blocks, wood engravings, etc. using such a
press. (Wikipedia 27th Sep 2010 Online)
Gravure – Rotogravure
(roto or gravure for short) is a type of intaglio printing
process, that is, it involves engraving the image onto an image carrier. In
gravure printing, the image is engraved onto a copper cylinder because, like
offset and flexography, it uses a rotary printing press. The vast majority of
gravure presses print on rolls (also known as webs) of paper, rather than
sheets of paper. (Sheet fed gravure is a small, specialty market.) Rotary
gravure presses are the fastest and widest presses in operation, printing
everything from narrow labels to 12 feet (4 m)-wide rolls of vinyl
flooring.
Typical gravure printed products include:
Food packaging
Wall paper
Wrapping paper
Furniture laminates
Panelling
Greeting cards
Magazines
(www.pneac.org/gravure
27th Sep 2010 Online Article)
Screen Process - SILK SCREEN PRINTING has its origins in
Japanese stencilling, but the screen printing process that we know today
probably stems from the patents taken out by Samuel Simon of Manchester at the
turn of the century. He used silk stretched on frames to support hand painted
stencils, a process also used by William Morris. In 1914 John Pilsworth of San
Francisco also took out a patent for multicolour printing, using the screen
process.
During the First World War in America screen printing took off as an industrial
printing process; it was mainly used at first for flags and banners but also
for 'point of sale' advertising in the chain stores in America, which were
appearing around that time.
Around this time the invention of the photographic stencil revolutionised the
process; in the following years, obviously improvements were made in the
presses, inks and chemicals used, but apart from the introduction of computer
technology in the 1980's - in the pre-press side of screen-printing - very
little else has changed since.
How does it work? The
equivalent of the printing plate for the screen printer is the SCREEN - a
wooden or aluminium frame with a fine nylon MESH stretched over it. The MESH is
coated with a light sensitive emulsion or film, which - when dry - will block
the holes in the mesh. The image that needs to be printed is output to film
either by camera or image-setter. This film positive and the mesh on the screen
are sandwiched together and exposed to ultra-violet light in a device called a
print-down frame. The screen is then washed with a jet of water which washes
away all the light sensitive emulsion that has not been hardened by the
ultra-violet light. This leaves you with an open stencil which corresponds
exactly to the image that was supplied on the film. Now the screen is fitted on
the press and is hinged so it can be raised and lowered. The substrate to be
printed is placed in position under the screen and ink is placed on the top
side of the screen, (the frame acts also as wall to contain the ink). A rubber
blade gripped in a wooden or metal handle called a SQUEEGEE (not unlike a giant
wind-screen wiper) is pulled across the top of the screen; it pushes the ink
through the mesh onto the surface of the substrate you are printing. To repeat
the process the squeegee floods the screen again with a return stroke before
printing the next impression. (www.printmaker.co.uk last edit 01.08.2010 collected on:
27th Sep 2010 Online)
Digital Printing
Laser Printing – A laser
printer is a computer printer that produces high resolution output by means of
a process that is similar to photocopying. In place of reflected light from an
image a laser printer uses information sent from a computer to turn a laser
beam on and off rapidly as it scans a charged drum. The drum then attracts
toner powder to the areas not exposed to light. Finally the toner is fused to
paper over a belt by heated rollers. In a write-black printer the laser
positively charges the printed areas to attract the toner which gives better
detail than a write-white printer. In a write-white printer the beam negatively
charges the areas not to be printed to repel the toner, which gives a denser
image. Faster, quieter and capable of producing more attractive results than
standard printers, laser printers have become an important means of printing
business documents since they became generally more available for personal
computers. (www.encyclopedia2.com 27th Sep 2010 Online)
Inkjet - An inkjet printer
is a type of computer printer that creates a digital image by propelling
variably-sized droplets of liquid material (ink) onto a page. Inkjet printers
are the most common type of printer and
range from small inexpensive consumer models to very large and expensive
professional machines.
The
concept of inkjet printing dates back to the 19th century and the technology
was first developed in the early 1950s. Starting in the late 1970s inkjet
printers that could reproduce digital images generated by computers were
developed, mainly by Epson, Hewlett-Packard and Canon. In the worldwide
consumer market, four manufacturers account for the majority of inkjet printer
sales: Canon, Hewlett-Packard, Epson, and Lexmark (Wikipedia 27th Sep 2010 Online)
Web - Web offset is a
form of offset printing in which a continuous roll of paper is fed through the
printing press. Pages are separated and cut to size after they have been
printed. Web offset printing is used for high-volume publications such as
mass-market books, magazines, newspapers, catalogs and brochures.
There
are two methods of web offset printing, known as heat set and cold set (or
non-heat set). In the heat set process, the ink is dried rapidly by forced-air
heating. In the non-heat set or cold set process, the ink dries more slowly by
ordinary evaporation and absorption.
Some
web offset presses transfer text and images to only one side of the print
medium at a time. Others can print on both sides simultaneously. The paper
width is usually between 11 and 56 inches (approximately 28 and 142
centimetres). The paper is fed through the system at speeds ranging from 5 to
50 feet per second (approximately 1.5 to 15 meters per second). (www.whatis.techtarget.com
27 Sep 2010 Online)
Desktop Publishing - Desktop
publishing began in 1985 with the introduction of Mac Publisher, the first
WYSIWYG layout program, which ran on the original 128K Macintosh computer. Desktop
typesetting, with only limited page makeup facilities, had arrived in
1978–9 with the introduction of TeX, and was extended in the early 1980s by
LaTeX.) The DTP market exploded in 1985 with the introduction in January of the
Apple LaserWriter printer, and later in July with the introduction of PageMaker
software from Aldus which rapidly became the DTP industry standard software.
Desktop publishing is the
use of the computer and software to create visual displays of ideas and
information. Desktop publishing documents may be for desktop or commercial
printing or electronic distribution including PDF, slide shows, email
newsletters, and the Web.
TRADITIONAL DEFINITION: Desktop publishing is the use of the computer and
specialized software to create documents for desktop or commercial printing.
Desktop publishing refers to the process of using the computer to produce
documents such as newsletters, brochures, books, and other publications that
were once created manually using a variety of non-computer techniques along
with large complex phototypesetting machines. Today desktop publishing software
does it all - almost. But before PageMaker and other desktop publishing software
there were e-scales, paste-up, and other non-desktop computer ways of putting
together a design for printing.
