More than Offset
Printing - Digital Printing and Copiers
printers have only used offset printing for their production needs in
catalog printing or magazine printing. Today's technology dictates a new
printing solution-digital printing.
the difference between offset printing and digital printing for your production
needs. Particular projects require alternative sheetfed printing, offset
printing or digital printing based on your specifications. If you require
catalog printing or magazine printing projects, the choice between these
kinds of printing can affect the outcome of your job.
better understand offset printing, sheetfed printing and digital printing
and the technology that dictates all three, read on below.
Find out the difference between
offset & digital printing
Printips: April 2004
A Defining Moment: Offset and Digital Printing
As a printer, our job is to have the right kind of equipment available
to produce your printing project. Years ago, being a printer meant having
offset printing presses. Today it also means having digital printing equipment
and high-speed copiers.
For some printing projects, the choice of which equipment to use is strictly
a production consideration - which piece of equipment has an opening in
the production schedule at the appropriate time. For other projects, there
is only one piece of equipment that can be used. And for yet others, the
choice of equipment is a complicated decision based on a variety of factors.
In this issue, we'll explore how the technology of each type of equipment
helps determine its range of use.
The technology of offset printing
Today's offset printing press is based on a technology called lithography
- literally, writing with stones. The image to be printed was engraved
on a flat plate made of stone that was inked and put in contact with the
sheet of paper. To keep ink away from the areas of the plate not engraved,
the plate was flushed with water. Because water and ink repel each other,
the ink adhered only to the engraved area of the plate.
Today's offset press uses the same basic technology - ink and water don't
mix, and a plate is required to carry the image. In original lithography,
the plate containing the image contacted the sheet directly, whereas in
offset printing the image is transferred from the inked plate to a rubber
blanket that contacts the sheet. The image offsets from the plate to the
blanket, then offsets again from the blanket to the paper.
The technology of digital printing and high speed copying
When we talk about digital printing, we are referring to high-speed laser
printing. Laser printing uses a single source of concentrated light to
expose the image on to photosensitive material located on a drum or belt.
Electrically charged toner is attracted to the image on the drum or belt
that has an opposite charge. Finally, the toner particles are transferred
to the paper and fused to it with heat and/or pressure.
In the past decade, most copier manufacturers developed digital printer/copiers.
These machines combine laser print engines with high-speed scanners to
enable image capture in digital format instead of the electrophotographic
method of analog copiers. Thus, all printing is from digital images, whether
provided by the scanner or by a computer file. These machines also have
copier features such as image manipulation, collating, stapling and bookletmaking.
For showcase printing, offset is the clear choice
For showcase printing projects, the overriding consideration is print
quality. So even though digital printing technology has improved immensely
over the past decade, offset printing is still the leader in image quality
for showcase printing projects such as fine art prints. This is because
an offset press plate can be imaged to a higher resolution than a digital
printing image carrier and because ink is a film while toner is particulate.
Ink film will adhere more exactly to a fine line or small dot than a particle
of toner, whose size may be larger than the line or dot it is adhering
For business printing, the choice is less clear
Unlike showcase printing, business printing projects often must accommodate
factors in addition to print quality. Cost is one, as is the amount of
time to produce the job, the quantity required, the kind of paper that
must be used, color fidelity or the format of the original.
Table 1. Comparison of Factors Affecting Choice of Offset or Digital Printing
Scanner or computer file
2400 x 2400 ppi
600 x 600 ppi
CMYK or PMS match
CMYK, PMS or RGB
Cost per image
Declines as quantity increases
Fixed throughout run
The strengths of offset printing are image resolution, reproduction speed,
paper selection and the declining cost per image as the print run lengthens.
In general, we will recommend offset printing when your project is 5000
pieces or more; when the image contains fine lines, photographs, screens
or tints; and when you want to use a thick or coated stock.
The strengths of digital printing are that once the image is at the printer,
nothing more is required to produce the first print; the sheets can be
handled, folded, cut or padded immediately after being printed; and an
RGB color image can be printed. In general, we will recommend digital
printing when you need your project quickly, especially if bindery operations
(such as folding, cutting or padding) are required immediately; and if
you need only a few copies.
The effect of document file preparation
Depending on how you prepare the document for your printing project, you
may unintentionally prevent us from being able to use the best technology
for the specific job. Remember that the image carrier for offset printing
is a printing plate. Each color in the job requires a different plate.
Therefore, the program used to create the file must support color separation.
Page layout programs that support color separation include Adobe PageMaker
and InDesign; Quark XPress; and Microsoft Publisher. Programs that do
not support color separations include Microsoft Word, Microsoft PowerPoint
and Microsoft Excel. If you create a document in any of these programs
and want it to print in more than one color, or if you include Microsoft
Metafiles as graphics, we will not be able to make press plates from the
file. In addition, since these programs are not for page layout, we are
likely to encounter other problems even if the job is printing in only
Finally, offset printing ink is either the four process colors (cyan,
magenta, yellow and black) or solid colors mixed using the Pantone(r)
Matching System. Files using RGB color have to be converted to CMYK to
make press plates.
Bring us in early
To be sure you have the most options and prepare your files correctly
for the technology we will be using, bring us in early in the planning
process. We'll discuss the pros and cons of each technology for your specific
job and give you tips for file preparation. Call www.printlocal.com at
877-816-4448 for more information.
Collating: accumulating printed sheets in a given order.
Clipping: color shift caused by the inability of one color space to reproduce
all the colors of another color space. Values in the source color space
that are outside the gamut of the destination color space are forced into
Gamut: the total range of colors produced by a device.
Hue, Saturation, Lightness: the three attributes of color. Hue refers
to the name of a color; saturation is color intensity; lightness (also
called brightness) is the degree of lightness or darkness.
Laser: acronym for light amplification by stimulated emission of radiation.
Lithography: the art or process of putting designs or writing, with a
greasy material, on stone, and of producing printed impressions therefrom.
The process depends, in the main, upon the antipathy between grease and
water, which prevents a printing ink containing oil from adhering to wetted
parts of the stone not covered by the design. (definition from Webster's
PDF: acronym for Portable Document Format. Cross platform, device-independent
file format developed by Adobe and based on its PostScript language. A
PDF file embeds all fonts and preserves formatting, colors and graphics
of any source document.
RGB: the additive colors red, green and blue used to produce the color
in computer monitors.
Toner: mechanically pulverized or chemically grown imaging agent used
in electrophotography. Consists of plastic resin compound, pigments and
Q. What file formats do you accept?
A. For documents, our standard file formats are PDF (portable document
format), Quark XPress(tm), Adobe PageMaker(r), Adobe InDesign(r) and Microsoft
Publisher(r). For single color printing or for digital output, we also
accept Microsoft Word(r) files.
We support both Windows(r) and Macintosh(r) operating systems. We are
an Adobe(r) Service Provider, a Quark(tm) Authorized Commercial Printer,
and a Microsoft(r) Publisher(r) Service Provider.
We recommend that you create your document files in one of our standard
programs because these programs are designed for page layout, assembly
and publishing. They also support color separations. This will give you
the most flexibility when it comes time to decide whether to use offset
or digital printing.
We have accepted and successfully printed documents created in Adobe Photoshop(r)
(a image editor program), Adobe Illustrator(r) (a drawing program), Microsoft
PowerPoint(r) (presentation software) and even Microsoft Excel (r) (spreadsheet
software). However, this adds time and cost to the production process
and severely limits our ability to produce the best quality printed product.
Tricks & Tips
A proof is our way of ensuring that we understand your instructions for
design, layout, typesetting and color. Depending on the complexity of
your project, several rounds of proofing may be required. We do not proceed
to print until you are completely satisfied with your proof and have authorized
us to proceed.
We have several ways to provide proofs: soft proofs are PDF (portable
document format) files sent to you as an attachment to e-mail or viewed
via a link to our web site. Hard proofs may be FAXed to you or you may
come to our shop to view them. We recommend soft proofs as you will be
able to check color and can easily share the proof with others in your
organization that may need to see it.
Even if you have provided a print ready electronic file for us to use
as artwork, we will still provide a proof. This ensures that nothing irregular
has occurred during transfer of the file to us and provides a chance for
you to see how our raster image processor has rendered the file. Although
this step may seem unnecessary, we feel it is better to take a little
extra time than to try to recover from an error caught on press.
One of the limitations of digital printing is the kind of paper stock
that can be used in the printer. The characteristics of a digital printer
that affect its range of papers include the heat generated by the fusing
rollers, the paper feed system and the paper path. Here are our recommendations
for paper to use when you select digital printing:
* For bond papers, a 24# basis weight paper tends to move more smoothly
through the paper rollers, resulting in better feed and less change of
* A smooth textured paper produces a superior image, while a paper with
a heavy texture risks uneven toner laydown, resulting in broken type and
spotty image reproduction.
* Papers for digital printing are manufactured with a lower moisture content
than paper used in offset printing. This counteracts the curl generated
by the heat of the fuser rollers.
Be aware that coated papers and some cover stocks may not feed well or
may travel inconsistently along the machine's internal paper path. For
this reason, we may ask you to limit your selection of these papers to
very short print runs (100 or less).
7 Park Avenue Suite 24
New York, NY 10016