Blind Recognition
features
Rainbow
Printing
In our simple analysis of a banknote
we saw that for each colour printed during the litho process,
a different printing plate is required. However this is not
strictly true! It is possible to divide the ink duct feeding
the printing plate into sections and place different colours
side by side. During the printing process the inking rollers
oscillate and this leads to a natural blending of the colours.
This is called rainbowing.
In our example we have a design
that rainbows from blue to green to yellow to green and back
to blue again. This can be achieved by having just blue and
yellow ink in the ink duct. The green is caused by the yellow/blue
blending.
Commercial printing presses are
not designed for this type of procedure and hence rainbow printing
not only adds aesthetic value to notes but also adds complexity
to some counterfeiting techniques.
Anti
Copy Features
Colour copiers and electronic scanners
have become a major counterfeit threat in recent years and bank
note producers have designed features that are not easily reproduced
by these types of machines.
Anti copy features are generally composed of fine lines or dots
and often have the word "VOID" or "FAKE" embedded within them.
If copied these features are reproduced in a "distorted" form
compared to the original, throwing up secret messages or interference
effects.
See Colour
Copier for further information
See
Through Features
The precision equipment used to
print back notes enables the back and front of the litho portions
of the notes to be printed simultaneously. They can also be
accurately registered to one another.
A feature utilising this accurate registration capability is
the see through feature. It comprises of 2 different images,
one on the front and the other on the back. When the note is
held up to the light a third image is produced by the combination
of each image.
Microprinting
Tiny messages can
be worked into designs and printed by both the intaglio and
litho printing processes. With most, if not all counterfeiting
techniques these tiny messages are lost, so in that respect
they offer good protection.
Intaglio
Detail
This is not strictly
a design feature but the hand engraving mechanism by which intaglio
images are initially generated produces such tonal variety and
detail that it is in itself is a security feature.
Details such as those seen on the right are difficult to capture
by any counterfeiting technique and as a results areas in which
Intaglio is primarily used generally appear flatter and lacking
in the tonal variety seen in an original.
Latent
Images
Latent images are produced by intaglio
print and the protection they offer is directly a result of
the tactile nature of intaglio print. When viewed straight on,
a latent image reveals nothing but lines...and that is if you
look closely! But viewed at a glancing angle an image appears.
This is a result of the intaglio print occluding the paper and
creating a contrast.
Blind
Embossing
The paper deformation that occurs
during Intaglio printing is sometimes used as a feature in it's
own right or can be used to produce an embossing effect of a
feature produced by the lithographic process. It is also possible
to produce inkless latent image effects using blind embossing.
Blind
Recognition Features
It is often difficult for people
with impaired vision to discriminate between one denomination
and another and features have been developed to assist them.
The features are often shapes printed in different colours.
For example, a red circle might be used on a lower denomination,
and a blue triangle on a higher denomination. Very often blind
recognition features also have a tactile effect built into them
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