fingerprints, or other marks. Use a camel's hair brush to remove any
dust, unless you find the mirror badly soiled. To remove any heavy
soiling, use a clean, lintfree cloth or lens tissue. However, this is
a last resort cleaning because it scratches the surface of the mirror
and creates more damage.
(3) Removing and replacing a lamp. When the projection lamp burns
out, replace it through the rear door after unplugging the projector and
allowing it to cool. Remove the old lamp by gently pushing down on the
lamp, turning it counterclockwise onehalf turn, and removing it from
the socket. Install the new lamp by aligning the socket ears with the
matching slots in the lamp socket, gently pushing it down, and turning
it clockwise to lock it in place.
(4) Maintaining the motor. The projector's motor has impregnated
bronze bearings that require lubrication with light oil every six
months. Remove the front grille of the projector for access to the
PART C PRINT PROCESSES AND PREPARING OVERLAYS
Regardless of the method used, printing transfers an image to a surface.
As an illustrator, you give ideas in an intelligible graphic form. In
many cases, printing is the last step in the process. It puts your
ideas in the final form that presents the idea. There are three
different methods of printing: (1) letterpress or relief, (2) intaglio,
and (3) lithographic or planographic (figure 222).
a. The Letterpress or Relief Printing Process (figure 223). This
form of printing is the oldest form and is still widely used. Relief
started as the art of wood carving in which the printer gouged out the
area of the wood not meant to be printed. This causes a design or
letter that stands in relief.
A relief printing surface always produces a letterpress copy. Whether
the printing surface is a single printing plate or a combination of one
or more plates, they are usually metal with the relief created by a
photoengraving process. However, occasionally the type is still hand
set by the printer.
b. The Intaglio Printing Process (figure 224). The intaglio
printing process uses a plate that has the letters or graphics etched
below the surface. After inking the plate, a roller wipes it clean.
However, the ink remains in the etched letters or graphic. Therefore,
when forcing paper against the surface, only the inkfilled areas
reproduce. Printers use this process to print engraved stationary,
paper money, and postage stamps.