Early origins.
Silkscreen Printing has its origins in
Asia as early as 2500 B.C. as a form of image repeat using sealed
cloth and dyes, but the screen printing process that we know today
stems from the patents taken out in 1907 by Samuel Simon of
Manchester. He used silk stretched on frames to support hand sealed
stencils.
In 1914 John Pilsworth of San Francisco also
took out a patent for multi color printing using the screen process,
employing early industrialized mechanization. During the First
World War in America screen printing took off as a commercialized
printing process; it was mainly used at first for flags and banners
but also for 'point of sale' advertising in the dept. stores of
America, which were evermore embracing graphic advertising.
Around this time the invention of the photographic stencil
revolutionized the process. In the following years, dramatic
improvements were made in the presses, inks and chemicals used. The
introduction of computer technology in the 1980's changed the
pre-press side of screen-printing, but the photographic method of
"sealing" the "screen fabric" remains much the same.
Many practical applications
It is the broad variety of screen thickness/ink thickness that has
given screen printing a unique place among all print processes.
Examples of screen printed items are everywhere. It is still a
primary method for traditional signage, decals, banners, and POP.
Many appliance control consoles and panels are multilayer printed
switches and graphics combined. The printed and etched circuit
boards in electronic equipment, flat panel glowing displays in cell
phones and dashboards, flexible circuits,
antennas, and digitizers all utilize screen printing as a
manufacturing step in product construction. Of course, the oldest
and most well known application is the use of screen printing to
decorate clothing, fabrics, and soft-goods.
Fine artists have also used screen printing as a medium for
expression, especially since the days of pop art in the sixties.
Andy Warhol is one of the few well known examples. These artists
opened up a whole new vista in the use of the screen process, and
contributed to the development of a large, limited edition method of
gallery marketing and distribution. It is one of the only printing
methods that can still be produced by hand if desired.
A brief description of the process.
A
4-sided frame is used with fabric mesh stretched over it. The mesh
is coated with a light sensitive emulsion or film, which will
eventually enable sealing non-image holes in the screen. The image
that needs to be printed is output to a film positive. This film
and the emulsion-coated mesh on the screen are sandwiched together
and exposed to ultra-violet light. 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 handle called a squeegee (not unlike a giant
wind-shield 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.
This method is altered to fit the requirements of the object to be
printed, and often is quite different from this same process adapted
to fit the decoration needs of another type of object.
Some items require basic accommodations, other need to screen print
with a high level of complex controls.
Bibliography and further reading:
The Thames
and Hudson Manual of Screen Printing by Tim Mara 1979
Screenprinting: water-based techniques by Roni Henning,
published by Watson- Guptill 1994
Ken Tyler
Master Printer by Pat Gilmour, published by Hudson Hills
Press 1986
The New
Guide to Screenprinting by Brad Faine, published by
Headline 1989
