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CD
& DVD Printing in detail
There are 4 ways of printing directly onto CDs and
DVDs, each has their benefits and are suited to
particular requirements:
- Thermal Transfer Printing
- Inkjet Printing
- Screen Printing
- Offset Litho Printing
Thermal Transfer Printing
The thermal transfer printer uses a horizontal array
of many small heating elements to melt "ink"
from a wax ribbon, which moves in tandem with the
CD, past a stationary print head. The print head
transfers those dots to the CD face to form the
image.
There are 2 types of thermal transfer print on a
CD - single colour and full colour.
a) Single Colour (usually black): This is the simplest
form of CD printing and is ideally suited to two
applications. Firstly, if the CD simply requires
a description of the contents (e.g. software patches
& bug fixes) then this provides a cost effective
and time saving solution. Secondly, if your CD products
need to have similar looking labels across different
titles (e.g. to retain a corporate identity), costs
can be reduced by screen printing the generic images
and text in bulk, and then thermal printing in smaller
batches the specific information, such as CD title
and version number, onto a designated area of the
disk. A disadvantage of this process is that the
print resolution is quite low (about 200dpi) which
means that images/logos and very small text can
look a little 'fuzzy'.
All single colour thermal printing is done in-house.
b) Full Colour: The results produced on full colour
images are excellent, however with all printing
methods there are advantages and disadvantages.
Towards the end of 2003 we trialled a full colour
thermal printer and found the overall image quality
to be very high. It printed images quickly and produced
a "hard and scratch-resistant" finish,
however, text was quite 'fuzzy' and the smaller
text (10pt and under) could become unreadable. Other
disadvantages were that the unit cost of the CD
is higher, and the flexibility for colour matching
was not comparable with our current in-house print
solution. Weighing up these points we felt that
there would be no benefit to our clients in offering
this solution.
Inkjet Printing
Using heavily modified inkjet printers, this is
a digital print process, and with a great number
of our clients, is the preferred method of print
as the resolution is so high (1440dpi). If your
artwork has a lot of fine detail, or you are using
graduated tints, then the definition provided by
inkjet printing provides a very effective result.
It is a very flexible printing process as it is
relatively quick and the colours can be matched
effectively to other printed material. Due to the
fact that each CD is printed digitally, there is
no need for plates or screens, so it is a very cost
effective print method for low volumes - even if
you want a proof before a job commences, one-off
samples are not a problem.
All inkjet printing is done in four colour process
(CMYK - Cyan / Magenta / Yellow / Black) which means
that Pantone (or 'spot') colours cannot be accurately
printed, however we have proven to be successful
in colour matching to Pantone colours when required.
As the ink is water based we always apply a protective
spray lacquer over the disk which protects against
accidental splashes.
Whilst inkjet printing is suitable for 90% of low
volume print requirements, it is not the best solution
where large blocks of heavy colour (e.g. dark blue)
are required, as these can be left 'soft' or 'tacky'
to the touch.
Like thermal printing, all inkjet printing is done
in-house.
Screen Printing
Screen printing uses fabric stretched tightly over
a frame (the Screen). Images are created by blocking
parts of the screen using photographic techniques
(the films). Ink is then forced through the open
areas of the screen onto the CD face. Each colour
printed requires its own film and screen, so a four
colour process job will need at least four films
and four screens.
The advantages of screen printing are that the CDs
can be printed very quickly (about 2000 per hour),
the resulting CDs are more scratch-resistant, and
the silver/mirror surface of the CD can be used
as part of the design.
The disadvantages are that whilst Pantone (or 'spot')
colours can be matched accurately, colour matching
four colour process printed CDs to other printed
material is difficult because of the different substrates
used. Also the resolution on four colour process
screen printing is not as high as with inkjet or
Offset Litho.
This is the conventional method for printing on
CD-ROM - the music CDs you buy will normally be
printed this way.
Offset Litho Printing
Offset is the process whereby a printing plate first
transfers its inked image areas onto a rubber blanket
mounted on a cylinder in the printing press and
then the rubber blanket transfers (or offsets) the
inked image onto the CD as it passes through the
press.
The advantage of using the Offset Litho process
is the very high quality of the print. Although
more expensive than screen printing, many clients
are willing to pay the extra to get the better results,
however Offset Litho printing is best suited to
larger quantities where the additional higher costs
become less significant.
This is the conventional method for printing DVD-ROM
- your movie DVDs will normally be printed this
way.
In Summary
Broadly speaking, the 4 print methods can be divided
into two camps:
- thermal transfer and inkjet for under 1000 CDs
- screen print and offset litho for over 1000 CDs
These rules are meant only as a guide since there
are occasions when, for example, we may need to
screen print only 500 CDs and conversely, inkjet
print 2000 CDs. The method you choose will depend
upon a number of factors, such as the quantity of
CDs, the quality of output, deadlines, and of course
price. We always have samples of each print method
available that we can send, so contact us on the
numbers below and let us help you to decide the
best print method for your project.
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