386 Graphic Communications
Drying
When the furnish leaves the screen, it enters
the press section, which removes more water. Then,
the paper enters a dryer section consisting of large
temperature-controlled rollers. More moisture is
removed. Coatings are applied as the paper moves
through the machine, Figure 21-5.
At some stage of the drying process, the paper
must be calendered. Calendering is the process of
fl attening and smoothing the paper surface by passing
it between a series of rollers. Supercalendering
uses heated steel rollers and pressure to form a very
smooth, high-gloss fi nish, Figure 21-6.
Rolling
The untrimmed paper is wound into rolls. Some
rolls are rewound, slit, and cut into lengths to make
fl at packages of paper. Others remain as rolls for use
in web-fed presses, Figure 21-7.
Watermarks
Wire
mesh
Dandy roll
Screen
wire mesh
MARK MARK
MARK
MARK
MARK MARK
A
B
Figure 21-4. Creating a watermark. A—The watermark
is simply a rearrangement of paper fi bers. It identifi es
the grade of paper or the trademark of a company. B—A
dandy roll is used to place the watermark on the paper.
Figure 21-5. Many of the papers used today for
magazine and book publishing are coated for better
reproduction of color and fi ne-screened halftones.
Coating is applied on the papermaking machine.
(Mead Publishing Paper Division)
Figure 21-6. Heated supercalender rolls are used to
smooth and polish the paper surface to a high gloss.
(Mead Publishing Paper Division)