TECHNOLOGY FOR TACTILITY IN SECURITY PRINTING

Petra Poldrugač, Ernela Šop

ABSTRACT

The paper shows how to achieve tactility in security printing. Analysis of historical securities gives evidence of relief as one of the first protective elements. Blind print on reverse side made by imprinted molds in the shape of the seal make relief on the face side. Over time the methods of achieving relief are changed, but the idea of tactile protection remained present. Today, relief is reflected in several aspects. Through the aesthetic appeal, it is possible to emphasize or reference to a specific graphic. For blind and visually impaired provides specific information about the product. At the level of safety set barriers for counterfeiters with specific types of security printing such as intaglio. A significant development of digital printing has enabled a new tactile dimension of protection with dry toner. A perfect precision register, simultaneous two-sided printing and determination of toner sediment give the possibility to design individualized protective relief elements.

1. INTRODUCTION

Security printing is based on several technology protections [1]. One of the first and basic are embossing. The importance is reflected in the way of detection. There is no need for special equipment or a particular type of radiation. Just take advantage of two unique and highly sophisticated sensors: the human eye and fingertips. Type of printing depends on the type of securities [2]. Banknotes are the most protected type of securities, so for their production intaglio print is using. Provision of machines is strictly controlled, and the printing principle is known only to specialists involved in the process. ID cards, passports, visas, bank checks, credit cards and others have tactile protection that allows fast authentication. Nowadays, the development of digital technology gives the possibility of individual tactile protection [3]. The ultimate artistic experience and the information defined with high relief on the surface protected tickets for sports or cultural events, gift vouchers etc.
Many historical banknotes were protected used embossed stamps, which are known as “blind” embossing [4]. It was very popular technique in the 17th and 18th centuries. As we can see in Republican France „assignat“ from 1793., the principle of  embossing was used to fit together and squeeze the fibers of the paper  to mark legal papers.

Picture 1  Republican France assignat from 1793.  and the position of blind embossing. Source Arheological museum Zagreb, inv.no. 1485

It have lost its popularity during the 19th century, but in 20th century returned to the protection of documents, especially for degrees, passports or certificates. On passports, identity cards or driving licenses is was used to link data with the picture. Today the picture is integrated into the document itself, so there is no need for that kind of protection. However there were still some modern banknotes that continued the tradition, for example Estonian 25 krooni note from 2007. 

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Picture 2  Blind embossing on Estonian 25 krooni banknote, first side (A), reverse side (B)

Today blind embossing can be used for document protection in combination with polymer or foil. Tactile laminate features like fine line patterns or microprint, are incorporated into security laminates by embossing.

2. TACTILE ELEMENTS FUNCTION ON SECURITIES

There is a three function of tactile elements: esthetic, information and protection. Esthetic role with three-dimensional relief provides highlighting of certain information and orientation to there position. That could be important for easy authentication, quick identification of securities types (egg nominal value of banknotes) or for overall artistic impression. The cooperation between security printing company Giesecke and Devrient GmBH, KBA-Giori S.A. and SICPA S.A. shows a great example of using intaglio print for automatic attention to the position of the nominal value on the banknote [5]. High diversity of color coat and different types of profile invite for more detailed study of the banknote that you hold in hand.

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Picture 3  Detail of  new sample note from Giesecke & Devrient 

Tactile elements could also be used to give greater importance to primary motive. In that way the blind and visually impaired people can recognize the shape. On the reverse side of the Zambia banknote of  50 000 kwacha there is a main motive of the tiger. Precise details of animals and stamping background gives the impression of a tiger in the foreground, while on the reverse of the banknote there are few other motives, some even larger dimensions.

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Picture 4  Tiger on Zambia 50 000 kwacha, reverse side of the banknote (A) and intaglio detail (B)

Information for blind and visually impaired people can be seen on almost all banknotes. Different shapes define the currency and the nominal value. It should be noted that on banknotes, until now, isn't possible to achieve the amount of relief that would enable tactile reading like Braille letter. Therefore, designers are oriented to simple marks, usually various geometric shapes that enable quick and easy identification. On Croatia kunas marks for the blind are circle, rhombus, quadrant, and there combinations [6].
Tactile features are also good protective element. In Croatia, the majority of counterfeit banknotes are imitated by scanning and printing on ink jet or laser printer. Relief obtained by application of paint is not enough for recognition.

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Picture 5  Detail printed with intaglio on genuine banknote (A) and print with ink jet on counterfeit banknote (B)

 3. NEW GENERATION OF TACTILE PROTECTION

On banknotes intaglio printing are often combined with other technologies. It is very common combination with hologram. Below are details of the 25 krooni banknote from Estonia and 50 000 kwacha banknote from Zambia. This combination is very effective protection because it combines two elements that can not be scanned and printed, and that their properties remain stable. Besides that, grouping and integrating security features simplify authentication control.

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Picture 6  Combination of intaglio print and hologram, 25 krooni banknote from Estonia. Inclined surface light (A) and white light (B)

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Picture 7  Combination of intaglio print and hologram, 50 000 kwacha banknote from Zambia. Inclined surface light (A) and white light (B)

Recent studies of tactile elements protection are increasingly turning to a combination of mechanical and laser engraving printing plates in order to create protection that can not be purposely  imitate with the existing equipment available on the open market. The bled-off intaglio design requires the production of entire printing plate in a single operation [7]. Comparing the current trend in banknote design it is evident that positioning of graphics printed with intaglio are in the middle. The first approach to the edge of the paper has successfully solved on banknotes of 200 and 500 euro - marks for the blind.

Picture 8  The bled-off intaglio on new sample note Clara Schumann from Giesecke and Devrient 
Source: G&D patents, 2010

We can conclude that intaglio printing is still superior protection for banknotes. High edition justify development costs. For all other types of securities intaglio printing is not cost effective. The development of digital technology gave unique solution for the low edition and high individualized editions, such as tickets, vouchers, lottery tickets etc. Professional digital printing devices such as Xeikon allow programmed, controlled toner layer by simultaneous two-sided printing.
Toner layer is baked and resistant to scratching and peeling. In table no. 1 there are values of measured toner layer of one, two, three and four colors on both sides.

Table 1  Toner layer in µm made on Xeikon on both side of the paper with one, two, three and four color

Colors don't have to be only process colors; it is possible to combine the spot, UV and IR colors. The relief is a result of controlled toner sediment individually for the face and back side.

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Picture 9  Graphics made with professional digital printing device with four color

Perfect register allows expansion of tactile security feature to segment. Components simultaneously printed on the face and reverse side looks like an art installation. Looking towards the source of light, the segments on the face and reverse side is a perfect complement.

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Picture 10  Segments printed on face side (A), back side (B) on white light, and graphics under DIA light

4. CONCLUSION

Technology for tactility in security printing are present for many centuries with minimum changes. Blind printing is used today also as a tactile protection. The changes are related to the development of digital technology that has enabled improvements from the manual to the laser engraving printing plates, and the development of new digital printing presses. It is expected the new combinations of protection elements and intaglio printing on banknotes, as well as a high paint layer that would allow reading for blind and visually impaired people, instead just recognition. For other securities future could be in the individual approach that enables digital printing devices with simultaneous double-sided printing programmed layers of toner and perfect register.

REFERENCES

1.  Van Renesse, Rudolf L.„Optical Document Security“, 3rd ed., Boston, London, Artech house, 2005., ISBN 1-58053-258-6 

2.  Kipphan Helmut,„Handbook of Print Media“, Springer-Verlag Berlin Heidelberg New York, 2001., ISBN: 3-540-67326-1 

3.  Žiljak Ivana, Klaudio Pap, Jana Žiljak-Vujić „INFRARED SECURITY GRAPHICS“, FotoSoft, ISBN 978-953-7064-11-2, ed.prof.dr.sc.Vilko Žiljak, 2009.

4.  Petra Poldrugač, Antun Koren, Ivana Žiljak, Tajana Koren » INFORMACIJE NA VRIJEDNOSNICAMA I NJIHOVA ZAŠTITA«, Informatologia, ISSN 1330-0067, Vol. 43, No 3, 2010, 160-169

5.  »INTAGLIO – THE HANDBOOK«, Line Communication Group LTD, 2002, Giesecke and Devrient GmBH, KBA-Giori S.A, SICPA S.A.

6.  »KAKO PROVJERITI IMATE LI ORIGINALNU NOVČANICU KUNE?« Hrvatska narodna banka, http://www.hnb.hr/novcan/hnovcan.htm

7.  »CLARA SCHUMANN – ART AND CRAFTSMANSHIP MEET PIONEERING BANKNOTE TECHNOLOGIES«, Giesecke & Devrient GmBH, 2010, PES 04/10 E 3.000 Art.-Nr.: 288 7153