Ink And Ink Manufacturing A consideration when selecting an ink is the
eventual use of the printed item. For example, food packages should be
printed with an odorless ink, ink on canopy tents
used outdoors must be able to withstand the weather, products that will
be handled by young children must be printed with non-toxic inks, ink
printed on table cloths
should hold up under repeated washings.
Printing ink is
transferred from a plate or stencil to paper or some other material
during the printing process. The ink forms the image on the printed
product. Over two thousand years ago, the Chinese made and used inks to
print from wood blocks. Most printing inks consist of pigments,
vehicles, and modifiers. Pigment is the ingredient that provides the
color of the ink. Many pigment colors are produced from rocks and clays.
Others can be traced to plants, sea life, or even insects. Several
pigments may be blended together to obtain a desired color ink. The
vehicle is the fluid that carries the pigment. Oil, lacquer, alcohol,
and water are all used as ink vehicles. Modifiers may be added to ink
for certain desired characteristics. For example, driers are added to
speed up the drying process. Waxes are used to minimize setoff.
Setoff
refers to the transfer of ink from a freshly printed sheet to the back
of the sheet above. Ink manufacture Ink manufacturing is complex and
requires extensive chemical and printing process knowledge as well as
specialized ink manufacturing equipment use. While there are a number of
manufacturing methods, most share these basic phases of production:
formulating, premixing, milling, filtration, and testing. Selecting the
right ink for the job Each printing process requires the use of an ink
developed specifically for that process. Letterpress, gravure,
lithographic, and screen-process inks are specially formulated to match
the requirements of the printing process. For example, letterpress inks
are designed to distribute evenly over and adhere well to raised plate
surfaces. Gravure inks are quite fluid and dry rapidly. Lithographic
inks are formulated so as not to absorb or combine with the fountain
solution in the press. And inks used for screen-process printing will
have the consistency of thick paint, which is usually required in this
process.
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