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Silk
screen printing has its origins in Japanese stenciling. It has since been
used by artists and designers like William Morris, Andy Warhol, Rauschenberg
and Hamilton.
It
was introduced in India as a cheaper alternative to block printing. The
silk screen is a wooden or aluminum frame with a fine nylon or silk 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 ultraviolet 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 ultraviolet light.
This leaves you with an open stencil which corresponds exactly to the image
that was supplied on the film. Next the fabric to
be printed is pinned on a wooden table so that it is evenly stretched
and there are no ripples.
Alternatively a wax
table is used. The surface of the table is covered with wax. Below there
are a network of pipes through which steam is passed. This causes the
wax to soften and the fabric is just firmly pressed on to the table.
The wooden frame of
the screen is fitted with metal handles which will fit onto to corresponding
wooden protrusions on the table. This is to aid placement, when two or
more colors are being used. The
dye is poured on the screen (usually pigment dye mixed thickly).
A rubber blade with
a wooden handle is firmly pulled across the top of the screen; it pushes
the ink through the mesh onto the surface of the fabric which is being
printed. Another person stands at the other side of the table. He takes
hold of the rubber blade and repeats the process.
Since the nonprinting
areas on the silk screen are blocked out, the ink is pushed through only
the porous areas corresponding to the design and is thus transferred to
the fabric.
If more colors are
used, the process is repeated with another screen and color. The screen is always
washed with a lot of water immediately after use. If this is not done,
the dye dries on the screen and clogs up the design.
The fabric is dried
and steamed as with the block printing process.
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