Joel Zlotnick, Tyra McConnell and Traci Moran
Counterfeit Deterrence Laboratory
Office of Fraud Prevention Programmes
Bureau of Consular Affairs
US Department of State

Introduction
Microprinting is primarily a security feature intended to combat digital counterfeiting, but it can also be optimised for other purposes. Part 1 and Part 2 of this series have explored the optimisation of microprinting artwork and colour, including ways that microprinting can combat sophisticated traditional counterfeiting while continuing to fulfil its conventional role against digital counterfeiting.  This third microprinting article shifts focus from counterfeit resistance to user ergonomics and alteration resistance. Although ergonomics and alteration resistance are different topics, both relate to where microprinting is placed within a complete security document. 

In the case of user ergonomics, a significant limitation of microprinting is that it can be hard to locate and inspect. To mitigate this disadvantage, predictable microprinting placement and the inclusion of cues to alert document users to the presence and location of microprinting can make it more accessible. 

For alteration resistance, offset or intaglio microprinting can be intersected with security features, bearer portraits, personalisation data or even letterpress serial numbers to provide evidence of tampering if these features are eradicated or changed. 

Throughout this article, microprinting graphics (Figures 1 through 33) are displayed in pairs, with the left image captured at lower magnification to show context in the document and the right image at higher magnification to show greater detail. The strategies described are presented for informational purposes and may or may not be appropriate for specific security document applications or manufacturable by all security printers. 

Single microprinting lines
Many of the microprinting artwork customisation techniques described in the first part of this series are most flexible when applied to larger microprinting patterns, but single lines of microprinting are often used where space is limited. One of the most typical placements for single lines of microprinting is at the edges of border designs as in Figures 1 and 2. To make the microprinting further stand out it can also be isolated from other artwork as in Figures 3 and 4. Although the microprinting still cannot be read without magnification, the single thin line might be seen more easily and may alert (or remind) document users where the microprinting is located prior to magnification. 

Figure 1: Blue offset and red intaglio microprinting placed at the edges of border artwork. Many documents follow this placement convention to make it easier for users to locate microprinting.
Figure 2: Positive and negative intaglio microprinting placed at the edge of an intaglio border design. Many documents follow this placement convention to make it easier for users to locate microprinting.
Figure 3: A single line of intaglio microprinting at the edge of a banknote, isolated from competing artwork to make it easier to locate before magnification is used.
Figure 4: A single line of intaglio microprinting at the edge of a banknote, isolated from competing artwork to make it easier to locate before magnification is used.

The documents in Figures 3 and 4 are banknotes that do not contain personalisation data, but microprinting is often included in one or more format or signature lines in birth certificates, passports and visas adjacent to locations that contain handwritten or printed bearer personalisation data. For example, Figure 5 shows microprinting in the signature line of a passport and Figure 6 shows microprinting in the format lines of a visa. These not only guide document users to locations where microprinting can be inspected but can also help expose alterations, which will be discussed in greater detail later. The single straight lines shown in Figures 1 through 6 provide limited opportunities for customisation of the microprinting pattern, but font customisation, multi-plate offset or multi-depth intaglio techniques as described in earlier parts of this series could still be applied. 

Figure 5: This passport signature line appears solid without magnification but is composed of microprinting. This placement makes it easier for document users to locate the microprinting but can also help reveal signature alterations. This example shows a single line, but Figure 6 shows multiple lines and Figures 24 through 26 show larger multi-line patterns that also resist alteration.
Figure 6: Single lines of intaglio microprinting underlining fillable text fields in two visas. This practice makes it easier for document users to locate microprinting, but in some cases can also help reveal alterations. See also Figures 5 and 24 through 26.

Multi-line microprinting patterns
Prior examples described some placements that make single microprinting lines easier for document users to locate, but multi-line microprinting patterns may be easier to see because they are larger and also offer more opportunities for customisation. Just like single lines of microprinting, multi-line microprinting patterns can be isolated from competing artwork and placed at edges or borders to make them easier to find, as in Figures 7 and 8. 

Figure 7: Multi-line offset microprinting patterns standing apart from competing artwork at the upper and lower edges of the same banknote. The size of larger microprinting patterns, along with their placements and environment, can help make it easier for document users to locate them.
Figure 8: Two front and two back corners of the same banknote, showing multi-line offset microprinting patterns standing apart from competing artwork. These larger microprinting patterns, along with their placements and environment, can help make it easier for document users to locate them.

Macro document artwork can also be used to alert document users to the presence and location of microprinting. Books, scrolls, plaques and monuments are thematic elements that document users may naturally associate with text. For example, the macro artwork of Figure 9 includes a book, with the text on its pages integrated as microprinting. Similarly, the text on the side of the monument in Figure 10 is actually microprinting.

Figure 9: Intaglio security document artwork featuring a book, with text on the pages of the book incorporated as microprinting. Use of the book in the macro artwork may be a cue to inform or remind document users where to find the microprinting.
Figure 10: Intaglio security document artwork featuring a monument, with text on its front incorporated as microprinting. Use of the monument in the macro artwork may be a cue to inform or remind document users where to find the microprinting.

In Figures 9 and 10 the non-text macro artwork helps document users anticipate the placement of microprinting, but design of text patterns alone might achieve the same thing without assistance from the macro artwork. As an example, Figure 11 shows six rows of text of different sizes. The upper rows contain larger text and can be read without magnification. Further, even without magnification document users can easily see that each lower row contains text of progressively smaller size. The readable top rows can draw attention and alert users to the presence of smaller microprinting in the lower rows. Figures 12 and 13 show similar implementations of multi-size text with the same result. The strategies shown in Figures 11 through 13 are one reason this series has made no effort to objectively define how small text must be before it becomes microprinting; these examples show that there can be advantages to microprinting patterns that include text of multiple sizes.

Figure 11: Intaglio microprinting of varying sizes in a single cohesive design. The larger text may be less secure against counterfeiter simulation, but it can be seen more easily to guide document users to the smaller microprinting. The smaller microprinting could be harder to simulate but might be more difficult for document users to locate if it were isolated from the larger text.
Figure 12: Multi-colour intaglio microprinting that changes size across the width of the design. The larger text may be less secure against counterfeiter simulation, but it can be seen more easily to guide document users to the smaller microprinting. The smaller microprinting could be harder to simulate but might be more difficult for document users to locate if it were isolated from the larger text.
Figure 13: Three-plate offset microprinting pattern that changes size across the width of the design. The larger text may be less secure against counterfeiter simulation, but it can be seen more easily to guide document users to the smaller microprinting. The smaller microprinting could be harder to simulate but might be more difficult for document users to locate if it were isolated from the larger text.

The examples in Figures 7 through 13 pertain to drawing user attention to discrete regions of microprinting, but another placement strategy is to incorporate microprinting throughout the entire background artwork. This occupies more surface real estate but makes it easy for document users to locate microprinting since it can be found anywhere. Examples of full-page microprinting designs are shown in a passport in Figure 14 and a stock certificate in Figure 15. 

Figure 14: Offset split fountain microprinting background artwork in a passport page, where the microprinting covers nearly the entire page. A document user could look for microprinting anywhere in this background and find it without difficulty. The wrong-reading text is a part of the design.
Figure 15: The borders of this stock certificate contain a guilloche pattern, but the background artwork throughout the interior is entirely microprinting. A document user could look for microprinting anywhere in this background and find it without difficulty. Some locations are highlighted to show microprinting behind a letterpress serial number, rubber stamp and handwritten numerals.

Microprinting and security halftones
Large microprinting patterns that contain repeating artwork can be at risk for step-and-repeat traditional counterfeiting. One way to make large microprinting designs more resistant to step-and-repeat counterfeiting is to incorporate microprinting in a security halftone. Halftones simulate a wide gamut of densities in a macro image by dynamically changing line width across a microscopic line art design, producing two distinct images with and without magnification. While typical halftones used in commercial printing are usually dot patterns, halftones in security artwork can be based on semi-randomised microscopic line art, such as geometric elements as in Figure 16, microprinting alone as in Figure 17 or a combination of shapes and microprinting text as in Figure 18. Security halftones were described in prior work and will not be examined in detail here, except to note that such halftones can be a vehicle for introducing microprinting into large areas of artwork. 

Figure 16: An offset security halftone based on various geometric elements but containing little microprinting text. Like microprinting, details in this artwork can be inspected with magnification but cannot be assessed as readable or unreadable in the same way. Compare to Figures 17 and 18.
Figure 17: An intaglio security halftone based entirely on microprinting and containing no geometric shapes. Microprinting throughout large areas of art makes it easier for document users to find and read. Although the font repeats between rows, the line thicknesses are different in each character to prevent step-and-repeat counterfeiting. Compare to Figures 16 and 18.
Figure 18: An offset security halftone based on a mix of geometric elements and microprinted text, with the microscopic image containing attributes of both Figures 16 and 17.

Whether a security halftone should contain graphics, text or both might be decided based on document user training considerations and other factors. Any artwork in Figures 16 through 18 would be tedious and time-consuming for a traditional counterfeiter to replicate since step-and-repeat processes are difficult if every individual shape or character features its own unique set of line widths. However, microprinting may be different from other types of security document artwork in that lay document users might more easily determine whether pure text is readable but may not be as comfortable assessing a security halftone composed only of shapes. If this is true, security halftones containing or based entirely on microprinting might have advantages. On the other hand, security halftones are complex and microprinting might be more understandable to lay document users in a simpler all-microprinting line or pattern that does not also contain non-text shapes that compete for user attention. The question will not be resolved here; as with all other content in this paper, whether microprinting belongs in a security halftone, or in other artwork elements, or both, is a matter for issuer discretion. 

Multi-plate and multi-process microprinting
Since each printing plate and/or manufacturing process used in a genuine document contains its own unique artwork, each plate design represents a fresh opportunity to incorporate microprinting. It is common for every printing plate in a security document to contain microprinting, but in most cases the microprinting is in different locations and users must search for it. For improved ergonomics, some of the microprinting from multiple plate images can be clustered in the same microscopic area to facilitate simultaneous inspection. Some examples featuring four colours of microprinting in the same location are shown in Figure 19. In Figure 19 the microprinting is offset and intaglio print, but microprinting can also be included in other processes and features like plastic substrate lamination plates as in Figure 20, optically variable devices as in Figure 21, and more.

Figure 19: Two different security documents, each containing microprinting in three offset colours and one intaglio colour. It is common for security documents to contain microprinting in various locations in every printing plate image, but in these examples microprinting from multiple printing steps was also placed in the same microscopic area so all can be inspected at the same time.
Figure 20: Clear tactile microprinting embossed into the surface of a polycarbonate passport data page substrate, shown on the left in oblique light and on the right in retroreflective light. Though composed only of clear plastic, the retroreflective light view shows at least three different microscopic textures that make this microprinting design distinctive.
Figure 21: Microprinting incorporated into an OVD design in multiple locations. The OVD is also intersected by offset microprinting in the background artwork. Microprinting can be included not only in offset and intaglio line artwork and OVD features, but also in security threads, planchettes, laminates and other document components.

Placement in similar documents
Some conventions exist for microprinting placement in similar documents. Similar documents could be all the visa pages in the same passport book, multiple denominations in a banknote series or another example of two or more documents from the same issuer that might be expected to look alike. In these examples, microprinting placement is usually related to better user ergonomics but can also contribute to alteration resistance in some circumstances.

Consider the three passport pages in Figure 22. In each page, the location of the microprinting is consistent, making it easier for document users to inspect it throughout the book. Likewise, the placement of microprinting at the same edge in each of the three banknote denominations in Figure 23 makes it easier for banknote users to find it. 

Figure 22: Offset microprinting in the corners of pages 17, 19 and 21 of the same passport. Consistency of design and location across pages makes this microprinting easier for users to locate and inspect. On each page the microprinting is customised with the page number to help prevent alterations.
Figure 23: Offset microprinting along the edges of three denominations in a banknote series. For better public accessibility and easier training of cash handlers, the microprinting is segregated from other artwork and is in the same location in each denomination. To prevent alterations, microprinting in each denomination is customised with the note value.

Microprinting and alteration resistance
Earlier articles in this series described strategies for microprinting resistant to both digital and traditional counterfeiting but did not address microprinting and document alteration. Protecting against alterations is a complex topic that exceeds the scope of this article because chemical and mechanical alterations require different defences, various document types are subject to different alteration attacks and multiple classes of anti-alteration security features are involved. But as with ergonomics, deliberate placement of microprinting can facilitate better document alteration resistance. 

In many cases, the element to be protected from alteration is applied over continuous offset or intaglio artwork. In truth other kinds of security line art can be used for the background, but these examples focus on microprinting. Examples include serial numbers as in Figure 24, bearer signatures as in Figure 25, inkjet or other digital personalisation text data as in Figure 26. Portraits are also commonly protected by application over a microprinting pattern, which can be printed in visible ink as in Figure 27 or with invisible UV-reactive ink as in Figure 28. In all of these examples, tampering with the protected feature risks damaging the continuity of the underlying microprinting (or other artwork) pattern, which contains details sufficiently small that counterfeiters could have difficulty restoring them if interrupted. 

Figure 24: Letterpress serial number applied over offset microprinting. Alterations to the serial number risk damaging the underlying microprinting pattern and revealing the alteration, particularly because the serial number print is translucent so the microprinting can be seen through it. Other kinds of security artwork can also be used for this function.
Figure 25: Microprinting in the signature panel of a passport page. Alterations to the bearer’s signature risk damaging the continuity of the microprinting pattern. Compare to the single line microprinting shown in Figures 5 and 6 and the full document microprinting shown in Figures 14 and 15. Other kinds of security artwork can also be used for this function.
Figure 26: Black inkjet personalisation applied over blue and green multi-colour intaglio microprinting background artwork in a visa. Alterations to the personal data risk damaging the continuity of the underlying microprinting pattern and revealing the alteration. Other kinds of security artwork can also be used for this function.
Figure 27: Offset microprinting artwork printed in visible ink, intersecting the portrait area of a passport. The portrait is translucent, allowing the microprinting to be read through the bearer image. Alteration of the portrait risks damage to the integrity of the microprinting. Compare to the UV microprinting design in Figure 28. Other kinds of security artwork can also be used for this function.
Figure 28: Offset microprinting artwork printed in UV-reactive invisible ink, intersecting a passport secondary portrait in visible light (left) and UV light (right). Alteration of the portrait risks damage to the integrity of the continuous UV microprinting pattern. Invisible UV-reactive ink does not compete with the portrait details in visible light, but this microprinting requires UV light to examine.

In other examples, static microprinting is applied over certain document components to help bind them more closely to a specific host document. These include offset or intaglio microprinting applied over the edges of optically variable devices (OVDs, a holographic security feature) as in Figure 29 or a windowed security thread as in Figure 30. The microprinting patterns in Figure 29 and 30 are smooth and continuous across the edges of the features, and discontinuity or interruption could indicate an alteration. Similar overlap strategies can be applied to a variety of other document components. 

Figure 29: Intaglio microprinting and latent image artwork printed across the surface of an OVD to help bind the OVD to this specific document. The microprinting should be perfectly continuous across the edges of the OVD. Misalignment or discontinuity in the microprinting could provide evidence of alteration to the OVD. As in Figure 21, the OVD design itself also contains microprinting.
Figure 30: Intaglio microprinting printed across the surface of a windowed security thread to help bind the security thread to this specific document. The microprinting should be perfectly continuous across the edges of the security thread. Misalignment or discontinuity in the microprinting could provide evidence of an alteration to the windowed thread.

One way that changeable data can be secured against alteration is redundancy, and microprinting is one way to introduce redundancy. The passports shown in Figures 31 and 32 contain laser engraved microprinting that includes the bearer’s personal data. Most static line art microprinting in security documents is intended to combat counterfeiting. In contrast, this personalised microprinting plays roles both in anti-counterfeiting (because its small size is a product of the laser engraving process that may be hard for counterfeiters to mimic) and anti-alteration (because it can be compared to larger duplicate text data printed elsewhere in the document). 

Figure 31: Laser engraved personalised microprinting of the bearer’s name in a polycarbonate passport data page, over offset line artwork that also contains microprinting. Use of laser engraving and personal data for this microprinting help the document resist alteration, and placement of personalised microprinting over static microprinting can increase alteration resistance even further.
Figure 32: Laser engraved personalised microprinting on passport data page (left). Multiple lines of laser engraved personalised microprinting across the portrait may make it easier for users to find (upper right). The long string of personalised laser engraved microprinting next to the long string of green static microprinting makes it easy to inspect both microprinting types at the same time (lower right).

Similarly, microprinting can be incorporated in secondary portraits, such as the inkjet secondary portrait in Figure 33 that incorporates the bearer’s unique personal data. Inkjet microprinting in a genuine document may be surprising since inkjet is often regarded as a tool for counterfeiting. However, in this application the anti-counterfeiting value is defined less by the resolution of the inkjet printer than by the software that generates the hybrid secondary portrait based on both the bearer’s face (macro image) and bearer’s personal data (micro image). As with all secondary portraits the example in Figure 33 can be compared with the primary portrait, so a counterfeiter would have to change both to produce a convincing alteration. 

Figure 33: Inkjet secondary portrait in a passport, featuring a microscopic pattern of text that includes bearer personalisation data. Unlike static offset or intaglio microprinting, the anticounterfeiting value is less about inkjet printing process resolution than the software process for creating the microscopic pattern, which could be challenging for counterfeiters to reverse engineer.

Conclusion
Although microprinting is not the solution to every document fraud problem, it remains a tremendously flexible design feature that can be optimised at relatively low cost to fill both primary and ancillary security roles. As the third and final instalment of a series concerning microprinting, this article has explored how microprinting placement can impact both user ergonomics and alteration resistance. Prior articles in this series have explored microprinting in terms of font and pattern design, ink selection and colour gamut, genuine issuer press capabilities and the importance of both resolution and registration in combating both digital and traditional counterfeiting. Issuers are encouraged to consider all of these facets of microprinting together, since combining all of the techniques presented throughout this series – artwork, colour and placement – may provide a pathway towards maximising the value of a microprinting design to improve document security without driving up costs. 

Read Part 1 and Part 2 of the series.

MORE ABOUT THE AUTHORS

Joel Zlotnick is employed by the US Department of State, Bureau of Consular Affairs, Counterfeit Deterrence Laboratory as a physical scientist. He conducts research on how design strategies can help maximise the security value of printing technologies and security features, and develops training programmes on counterfeit detection.

Tyra McConnell is a Forensic Document Examiner at the US Department of State, Bureau of Consular Affairs, Counterfeit Deterrence Laboratory. She provides training on security documents and develops presentations and e-learning courses regarding counterfeit detection.

Traci Moran is employed by the US Department of State, Bureau of Consular Affairs, Counterfeit Deterrence Laboratory as a physical scientist. She conducts research on security documents and delivers counterfeit detection training to varied audiences.

Disclaimer: This document represents the opinions of its authors and not necessarily the opinions of the US government. The technologies and strategies described may not be available, appropriate or manufacturable for all document issuers. The examples shown do not imply anything about the quality of a document, its designer, its manufacturer, or the issuing authority. For informational purposes only.

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