back to basics
Printing terms and definitions
Knock-out PDF Set-off
Since printing inks are not completely Portable document format. When ink from a printed sheet marks the
opaque, printing one ink over another will
Perfecting press
underside of the sheet above it.
create a third colour. To avoid this, a knockout
Sheet-fed press that prints on both sides Show-through
or unprinted area in the shape of the
of a sheet. A printed area showing through from the
foreground object is left in the colour plates
other side of a printed page due to the low
that make up the background.
Perfect binding
opacity of the paper.
Lamination
Method of book and journal binding using
A gloss or matt plastic film applied to the
adhesive rather than thread to hold the
Silk paper
paper after the printing process, to maximise
leaves together.
A smooth coated paper with a semi-gloss
Printing
finish and distinctive silky feel.
durability.
Polywrap
Lithographic printing
Thin polythene used as an alternative to Spot colour
A printing method using a flush printing and
envelopes in the mailing of printed materials. A colour that is printed using a specially
non-printing surface which is in contact with
Proof
pre-mixed ink, usually identified by a
paper. The non-printing areas are treated
Pantone number.
A copy of a document for checking prior
to attract water, which prevents ink from
to printing. TCF paper
attaching to it.
Totally chlorine-free paper.
Registration marks
Matt paper
Circles and lines that appear on the outside
Tip-on
Paper that has a flat finish.
of the page area that ensure the colour plates
An item glued onto a specific page within
Printing
Mechanical paper are properly lined up with each other during
a piece of literature.
Paper that contains mechanical wood pulp. the printing process.
Trapping
Offset printing
RGB
The process of intentionally overlapping

The most common form of lithographic
adjacent colours within a file to compensate
Red, Green, Blue. These colours make up an
printing, where a blanket is used to transfer
for mis-registration.
additive form of the four printing colours,
the ink to the printed area.
CMYK. In litho print, RGB scans should always UV varnishing
Overprint
be converted to CMYK for correct output. A gloss or matt coating applied to either the
To avoid problems with trapping, the
RIP
complete page or to a section of the page

background object is printed in its entirety,
after the printing process.
Raster image processor. This is the technology
Printing
with no knockout for the foreground item,
that converts PostScript page data to a high-
so the object colour sits on top of the
Web presses
res bitmap.
background colour. This is desirable when the
Printing presses that use paper fed from
object colour is black, or when you wish to
Saddle-stitching
a reel.
mix two colours to achieve a third colour.
A form of binding when the covers and
Woodfree paper
sections are stitched with wire.
Overs
Paper that contains little or no mechanical
Surplus printed material above that ordered.
Self-cover wood pulp.
When the cover is printed on the same
Pagination
paper as the rest of the product.
The number of pages within a product.
Pantone
A proprietary system providing a method
for the selection, reproduction, matching and
control of colour.
PCF paper
Process chlorine-free paper. Similar to TCF
(totally chlorine-free paper), but it can
contain post consumer fibre in the pulp
which contains traces of chlorine.
PEFC
Programme for the Enforcement of Forest
Certification. The PEFC certifies timber and
paper products to ensure that they have
been sourced from sustainable forests.
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