All About Printing Machines

Relief Printing

A printing master, or plate, is made in reversed
relief form, and the protrusions are inked and then applied to paper to
transfer the image. These masters can be made of wood, rubber or even metal
type, and are made up in the reverse image of the original.

Intaglio Printing

 

Intaglio printing takes the reverse approach. A
reversed relief form is made, but ink is applied to the master, then removed
from the protrusions so that only the depressions carry the ink to the paper
to transfer the image. This method is used for etching, dry point, and
gravure printing for magazines, brochures or other applications where
beautiful photos with superior resolution are desired.

Lithography

 

Instead of using a physical relief, this method takes
advantage of the physical law of "oil and water don't mix." Water is applied
to areas which are not to be printed to prevent the uptake of oil-based ink
by the master, resulting in the creation of an image. This method is used in
offset printing, which is the most widely used in the industry.

1. First, water is applied to the portions of the master
that represent areas which will not be printed.

2. Ink is then applied with a roller, but the ink can only adhere to those
dry portions of the master representing areas to be printed.

3. The master drum transfers its ink pattern (the image) to a blanket drum,
which then transfers the image to paper.

Screen printing

The master is perforated with a pattern of holes. Ink
is applied from the top, and flows through the holes to the paper below,
transferring the image to the paper. This is the method used by mimeograph
machines and other types of screen printing devices. Materials such as nylon
and stainless steel are used to create the master 'screen' which makes
direct contact to the paper each time a copy is made. This method is also
used in Ricoh's Priport digital printing machine.