Security printing

Security printing is the field of the printing industry that deals with the printing of items such as banknotes, cheques, passports, tamper-evident labels, security tapes, product authentication, stock certificates, postage stamps and identity cards. The main goal of security printing is to prevent forgery, tampering, or counterfeiting. More recently many of the techniques used to protect these high-value documents have become more available to commercial printers whether they are using the more traditional offset and flexographic presses or the newer digital platforms. Businesses are protecting their lesser-value documents such as transcripts, coupons and prescription pads by incorporating some of the features listed below to ensure that they cannot be forged or that alteration of the data cannot occur undetected.Recto of 1 Romanian Leu banknote (series 2005) with partially overprinted window on the left (polymer substrate)Recto of 20 euro banknote (series ES2) with holografic foil over the window (upper right side) (paper substrate)Verso of 20 euro banknote (series ES2) with holografic foil over the window (upper left side)Watermark in a postage stamp from Zululand (around 1900)Watermark in a 100 Deutsche Mark (series BBk-IIIa) from Deutsche BundesbankWatermark in a 100 euro (series ES1) from European Central BankWatermark in a 5 euro (series ES2) from European Central BankRecto of 100 euro (series ES1) (lower left)Recto of 20 Swiss franc (8th series)Recto of 1 US dollar with microprinting and guilloché in the pyramidOVI of 50 euro (series ES1)Emerald number of 5 euro (series ES2)Hologram on a 50 euro (series ES1)Hologram on a 100 euro (series ES1)Security thread of 100 euro (series ES1) (only visible in transmitted light)Security thread of 100 US dollar (series 2009) with the 3D security ribbonDetails of 3D security ribbon on 100 US dollarSecurity thread of 500 Russian ruble (series 2010) with hologramUS dollar (serie 2003) with green serial numberRussian ruble (series 2006) with variable font size (right)200 Guatemalan quetzal with lasered serial number (in the white area)Iranian rial with Arabic script and Eastern Arabic numeralsRecto (cutout) of 5 euro (series ES2)Recto (cutout) of 20 US dollar (as part of the value numeral 20)Recto (cutout) of 50,000 Korean wonRecto at 350 nmThe foil of the kinegram (bottom right) and colored fibres show upVerso at 350 nmThe colored fibres are clearly visibleRegistration pattern of 100 euro (series ES1) (recto)Registration pattern of 100 euro (series ES1) (verso)Registration pattern of 100 euro (series ES1) (transmission)Registration pattern of 50 Swiss franc (8th series) (transmission) Security printing is the field of the printing industry that deals with the printing of items such as banknotes, cheques, passports, tamper-evident labels, security tapes, product authentication, stock certificates, postage stamps and identity cards. The main goal of security printing is to prevent forgery, tampering, or counterfeiting. More recently many of the techniques used to protect these high-value documents have become more available to commercial printers whether they are using the more traditional offset and flexographic presses or the newer digital platforms. Businesses are protecting their lesser-value documents such as transcripts, coupons and prescription pads by incorporating some of the features listed below to ensure that they cannot be forged or that alteration of the data cannot occur undetected. A number of technical methods are used in the security printing industry. Security printing is most often done on security paper, but it can also occur on plastic materials. The substrate of most banknotes is made of paper, almost always from cotton fibres for strength and durability, in some cases linen or speciality coloured or forensic fibres are added to give the paper added individuality and protect against counterfeiting. Some countries, including Canada, Nigeria, Romania, Mexico, New Zealand, Israel, Singapore, Malaysia, England and Australia, produce polymer (plastic) banknotes, to improve longevity. They may include transparent windows (up to 10 millimeters in diameter) as a security feature in areas which are not covered by the opacifying layer. Paper substrate may also include windows based on laser-cut holes covered by a security foil with holografic elements. All of this makes it difficult to reproduce using common counterfeiting techniques. A true watermark is a recognizable image or pattern in paper that appears lighter or darker than surrounding paper when viewed with a light from behind the paper, due to paper density variations. A watermark is made by impressing a water coated metal stamp or dandy roll onto the paper during manufacturing. Watermarks were first introduced in Bologna, Italy in 1282; as well as their use in security printing, they have also been used by papermakers to identify their product. For proofing the authenticity, the thinner part of the watermark will shine brighter with a light source in the background and darker with a dark background. The watermark is a proven anti-counterfeit technology because most counterfeits are simulating its appearance by a printing pattern only. Printed with white ink, simulated watermarks have a different reflectance than the base paper and can be seen at an angle. Because the ink is white, it cannot be photocopied or scanned. A similar effect can be achieved by iriodin varnish which creates reflections under certain viewing angles only and is transparent otherwise. Watermarks are sometimes simulated on polymer currency by printing an according pattern, but with little anti-counterfeiting effect. For example, the Australian dollar has its coat of arms watermarked on all its plastic bills. A Diffractive Optical Element (DOE) within the transparent window can create a comparable effect but requires a laser beam for its verifcation. Intaglio is a printing technique in which the image is incised into a surface. Normally, copper or zinc plates are used, and the incisions are created by etching or engraving the image, but one may also use mezzotint. In printing, the surface is covered in ink, and then rubbed vigorously with tarlatan cloth or newspaper to remove the ink from the surface, leaving it in the incisions. A damp piece of paper is placed on top, and the plate and paper are run through a printing press that, through pressure, transfers the ink to the paper.