High-security printing for passport: The 2023 expert's guide
For authorities worldwide, the fight to protect passports against fraud remains as intense as ever.
Of course, the rapid adoption of electronic passport solutions over recent years has proved a significant step forward in terms of both homeland security and traveler convenience.
There's also fast-growing recognition of what polycarbonate data pages can do in thwarting attempts to tamper with or counterfeit passports.
Security printing techniques in 2023
However, we believe it's key that authorities do not overlook in 2023 the importance of a security-conscious approach to the paper elements of a passport's design and production.
After all, paper pages still make up the bulk of the document.
Moreover, they include the cover and end pages (glued to the inside of the cover) and the pages that hold the visa and entry and exit stamps.
And for those that have not yet migrated to polycarbonate, the paper will also form the basis of the all-important data page, which includes the holder's details and portrait.
To maintain an effective defense against counterfeiting, all these paper elements must be carefully considered.
Success will ultimately lie in making it as complicated, time-consuming, and expensive as possible for forgers to copy or compromise a legitimate document.
The good news for 2023?
A host of proven high-security passport printing techniques will help deter even the most determined and resourceful criminals when designing a passport in 2023.
In this article, we'll once again be slapping on our lab coats.
We'll provide readers with an expert guide on how best to use the paper elements to protect the integrity of what is, after all, a vital national asset.
In particular, we'll be posing a simple question: how can security printers such as Thales design the paper elements of a passport to make it much harder for counterfeiters to copy or imitate a document's visual aspect?
In line with the fundamental principles of any secure passport design, we'll find that the answer ultimately lies in the effective combination of various techniques. Specifically, these include:
Employing technologies that are difficult to copy.
Incorporating multiple security features - so a counterfeiter must master them all to stand any chance of success.
Using materials, technologies, inks, and components that are difficult for criminals to source.
Using inks and components that are only sold to secure printers.
Now let's look in detail at some of the techniques that can enhance the security of the paper elements and the passport as a whole.
We'll also consider how specific threats are countered by Thales' field-proven security features and processes.
Let's start at the end…
Passport end pages
End pages play a critical role in protecting the integrity of the whole passport booklet.
Access to the stitching – and hence the data page – should be prevented by using high-security printing methods on a secure paper substrate. This should be fully bonded and secured to the cover material.
A document's unique passport number is high on the list of assets that can be utilized in the fight against counterfeiting.
When a lost or stolen document is reported to the police, this will typically end up on an international watch list, such as the one maintained by Interpol.
Inevitably, fraudsters will attempt to change one or more digits, to try and ensure that the authorities are not alerted when the document is presented at a border checkpoint.
As well as the size, Thales can even vary the basic hole shapes forming the passport number - including circles, squares, and stars, for example.
Therefore, an effective endpaper design using laser technology will include burning the genuine document number through every page. This means going through all the visa pages and the back cover.
These numbers comprise small conical holes, the size of which varies according to the page number, making it even harder for counterfeiters to swap pages.
Intaglio printing: another powerful security tool (process)
A security printing technique known as Intaglio printing provides another powerful security tool. Thales typically incorporates latent images that can only be seen when viewed at particular angles.
This feature is immediately recognizable to those responsible for checking the document's authenticity and the broader public.
This familiarity reflects that Intaglio is a long-established security printing technique used for passports and banknotes.
Intaglio printing can create tactile effects.
Which process best describes intaglio printing?
The lines to be printed are cut into a metal plate through an etching process.
The ink is applied to the surface of the plate and pushed in the recessed lines.
A rolling press applies high pressure to push the paper into the recessed lines.
The area that prints is below the surface of the plate.
This creates a unique effect difficult for counterfeiters to replicate: it requires specialized skills and dedicated equipment. It can also be checked quickly only by running a finger over the printed page.
According to the Keesing Journal of Documents &Identity of June 2017, Intaglio remains a technique that cannot be replaced by inkjet or toner printing, at least for now. It is also barely accessible to counterfeiters. Tactile effects, in particular, are hard to reproduce.
Intaglio continues to offer a high level of security compared to digital printing.
And the security struggle doesn't stop there…
In addition to intaglio printing, endpaper print design can employ several anti-copy elements.
These include offset printing in four colors, UV 365 in two colors, and IR reactive inks.
Intricate design patterns will pose further challenges for fraudsters.
See here for a detail of the cover page of the Swedish passport under UV light. The front and backlights of cars on the roads only appear under UV and create a fantastic effect.
Ultra-thin security paper
Thin endpapers (no more than 85gsm) represent another asset for passport issuers.
In that case, being fragile is a strength.
Because the adhesive volume needed to bond the cover, combined with the calendaring effect of Intaglio print, means that counterfeiting attempts will be prone to glue seepage and staining.
Crucially, Thales can produce ultra-thin endpapers as durable in operation as fragile if attacked.
If a forger does try to separate the endpaper from the cover, it will be destroyed and rendered useless.
Belgian and Swedish passport front covers are shown here. Removing the thin inside cover paper is almost impossible with special embossing.
Solid bond: benefits of the moiré printing
As if all the above wasn't enough, consider a few more of the endpaper techniques that Thales employs on behalf of passport issuers:
According to individual customer requirements, unique high-security papers can contain visible and invisible fibers.
Bonding to the embossed cover material ensures no bubbles or creases on the end page.
Tiny laser-produced holes of various shapes make up the document's serial number, visible through the cover and endpaper. Any attempt to delaminate and re-use the endpaper will be immediately evident because the holes cannot be realigned.
Endpaper aligned perfectly with the cover material, defending against the addition of a counterfeit.
Thales further reduce counterfeiting risk by using a material that features a unique, highly detailed embossing registered to the document. If split, it leaves air gaps, and the end pages will not lie flat. Also, the inside front cover incorporates a letterpress serial number reproduced using specialist inks.
Therefore all the pages are numbered securely.
This process is difficult to replicate without specialist equipment; attempts to do so are recognized easily by border guards. Finally, Thales proposes a Moiré movement print effect.
This visual effect occurs when looking at a set of lines or dots suspended over another set of lines or dots. In this case, it is suspended over pre-embossed lines behind the print.
Moiré printing creates a wave effect when tilted on the 2017 Finnish e-passport.
Visa pages in passport printing
Now let's turn to the visa pages…
What's the best way to resist attempts to counterfeit these?
The Thales design studio utilizes the latest print security software to produce technically challenging copy designs.
The aim is to ensure that pages cannot be moved to hide a travel history or official endorsements or transferred from one document to another. For the visa pages, specific design elements available include security printing and cross-page designs.
Including a cross-page design means that a forger trying to replace a single page would need to match up all the visible and invisible elements on a substrate that held the same UV reflectance level.
Each page is a single sheet that passes through the central stitching. It is further locked down at this point, making extraction challenging.
Count on page numbering…
As we've already highlighted, Thales delivers passports with pages numbered consecutively throughout the booklet. It's an obvious way of reassuring that pages have not been removed to hide the holder's travel history.
These numbers are incorporated within the visible and invisible design when illuminated with UV at 365nm. They're also in offset print and incorporated into the design using bi-focusing lines, deliberate errors, and a see-through print register in at least three colors.
Bank on see-through for high-security printing
'See-through' is a design motif made up of two parts. One image is printed on the front, the other in precise register on the reverse of the data page/visa page. Under transmitted light, both models become visible, creating a complete element.
This feature has been present in most banknotes for many years. It is adequate protection against copying since it requires a specific machine sold only to high-security printers. This enables printing simultaneously on both sides of the paper.
In contrast, counterfeiters must print one side of a page before flipping it over and printing on the reverse. This results in a blurry image – fraudsters cannot perfectly align with the available equipment.
Special security printing inks and layers
Remember, the ultimate aim is to make it so tricky, time-consuming, and expensive for a counterfeiter to replicate a passport that it simply isn't worth their while to try.
This illustration shows the Estonian ePassport under UV lighting. The document integrates the papers' invisible yellow, blue, and red inks and UV-sensitive fibers. These fibers are approximately 3mm long and 25 decitex thick (10,000 m of thread weighs 25g).
At Thales, we, therefore, add even more layers of complexity:
Close alignment of the print and cross-page designs makes removing a single page more difficult.
Microprinting, nano text, and multiplex printing make replication still more challenging.
All visa pages are printed on security paper that has no optical brightener.
Designs incorporate at least four colors and are rainbow printed.
Special security printing inks are IR reflective or absorbent – but look identical in white light.
Thales also uses randomly distributed, visible, and invisible fibers, plus candy-striped fibers, which can react to long-wave (365nm) UV light. Furthermore, specific threads have a multi-UV reaction that will fluoresce in two colors, helping authenticate the substrate's legitimacy.
Fibers are inserted during the paper manufacturing process and appear randomly across the paper. Counterfeiters often simulate such visible and invisible threads using printing techniques, but they tend to drop the random patterns in doing so. Consequently, similar patterns on more than one passport page indicate that something suspicious is happening.
Fibers can also have a multi-color UV reaction.
Watermark: an essential element of robust passport design
The watermark is probably the most widely recognized secure printing feature in banks and stamps. And it remains a crucial element of robust passport design.
The watermarks are a Level 1 feature -visible to the naked eye - incorporated using a mold specific to the customer's design during the papermaking process. It appears as various shades of light and dark when viewed by transmitted light caused by density variations in the paper.
Thales employs a multi-toned cylinder mold watermark registered to the design for visa pages. To ensure optimum visibility, it is usually positioned in a reveal area. Also deployed is an electrotype or bright watermark identical on every visa page.
This can be used to provide additional information, such as page numbering.
More tell-tale signs of counterfeiting…
Watermarks are best viewed by holding the document up to the light or shining one through the paper. It is easy to verify, as a genuine watermark never reacts under UV light.
However, a chemically simulated one will likely respond, providing another tell-tale sign of counterfeiting.
Embedded security threads in visa pages
Thales inserts security threads into the visa pages in some of the passports it produces.
Like those used in banknotes, these are embedded directly into the paper during manufacturing.
They can be made from either plastic or metal, with customer-specific designs, and covered by paper or 'windowed' (i.e., visible on the surface of the window at regular intervals).
A windowed thread in the Swedish passport can be seen below under UV and normal light. This plastic security thread inserted in the paper features a visual effect whereby images of airplanes move in the opposite direction when the thread is tilted.
We're not through yet.
Edge design in visa pages
Edge design is also used in the fight against the counterfeiting of visa pages. Thales prints a different part of the edge of each page.
When viewed edge-on and the pages are spread, these form words in offset print.
Seen from the opposite side, UV characters are visible. Each page has floating and static page numbers in visible and UV printing.
High-security printing is visible at the edge – under normal light and UV light.
Chemical secure printing processes
Generally, there are only two main ways to remove an endorsement from a passport:
Abrading the endorsement away or scratching it off with a scalpel
Finding the correct solvent to dissolve the endorsement
Finding the right chemical is always tricky for a potential counterfeiter for the latter approach. Even then, pigmented indelible inks cannot easily be removed from the substrate.
A trace will almost always be left behind, which can be seen under UV or IR light or through damage to the paper fibers.
Water-based inks are easier to remove: border control authorities should ensure that the inks they use for control purposes are indelible or contain elements (such as UV reaction) that make them unique.
However, such an approach cannot be guaranteed. The modification threat must be countered by secure printing processes and unique substrate and reagents within the paper sensitive to chemical attack.
Many of the techniques already detailed in this article will make any such attempts apparent. For example, watermarks will become severely degraded or damaged should the page be split or abraded.
Furthermore, Thales' security paper contains chemical sensitizers that react to solvents. As a result, if a chemical is used to remove a visa sticker or border entry/exit stamp, the reagents are activated, leaving a visible stain on the page.
Solvents would also damage the offset and UV elements, causing them to deteriorate. Besides, the base fluorescence around the affected area would change and become brighter.
Passport stitching and sewing
End pages are essential in protecting against access to the stitching and hence the data page by fraudsters.
In this article, we've already outlined how processes such as high-security printing, bonding, and ultra-thin paper make counterfeiting extremely difficult.
But we also use very fine sewing threads to secure the booklet pages to the end pages and covers. A combination of different materials and colors further guards against dismantling and reassembly.
During manufacture, an automated system uses a consistent process to sew each passport individually, to the same specification, using three different strands of high-security thread. These are pulled and twisted, giving an equal number of turns between each hole.
The top and bottom three stitches are back-stitched and held in place with a locking stitch.
This is further sealed with spine tape containing a heat-reactive adhesive that makes the re-use of the thread impossible.
All stitch segments are of equal length. As the thread is made up of discrete strands, if dismantled, they separate easily.
You bet: this makes re-use extremely difficult, and any attempt at dismantling is readily identifiable.
Cover Material as a security element for printing
Finally, we've got the cover covered too…
We use a latex-saturated cover material. As already described, this is fully bonded with a combination of adhesives that permanently adhere to the cover and end pages to the passport.
The passport is stiff enough to lay flat yet flexible enough to permit secure bonding to the end pages.
The overall lesson of secure passport papers techniques and design
Over recent years, attention has inevitably focused on breakthrough technologies such as ICAO-compliant embedded software and protection mechanisms (EAC, SAC).
But it is equally crucial that secure software, and new materials, such as polycarbonate data pages, are not regarded as some form of "magic bullet."
A trulysecure passport design is the sum of its parts, which still includes a significant paper element.
Above all else, we have aimed to emphasize in this article that features such as end and visa pages are still high on the hit list for counterfeiters.
Equally, many security tools are at the disposal of passport printers and their customers to fight document fraud.
As a result, it is possible to deter even the most sophisticated efforts to modify and replicate genuine documentation with security printing techniques.
Any such attacks will be immediately apparent to border control staff (equipped with or without a document reader) and other law enforcement bodies.
How can we help you design a highly secure passport?
Thales has acquired in-depth know-how on paper technologies, delivering passports and ePassports since 1987. The company has an extended history of security printing activities, including banknotes, stamps, and bonds dating back to 1885.
At Thales, we believe in taking a comprehensive approach to security. We strive to provide secure, durable, and innovative solutions.
We're proud to have successfully designed some of the most secure and attractive passports, IDs, and driver's licenses to appear in recent years.
For more information regarding our services and solutions contact one of our sales representatives. We have agents worldwide that are available to help with your digital security needs. Fill out our contact form and one of our representatives will be in touch to discuss how we can assist you.
Please note we do not sell any products nor offer support directly to end users. If you have questions regarding one of our products provided by e.g. your bank or government, then please contact them for advice first.