At Angstrom Technologies, Inc., we believe a layered security approach is the best way to achieve optimal document security. Part of that layered approach includes using a combination of overt and covert security features that improve document security based on the detection methods needed to see them.
In our guide, we discuss overt vs. covert document security features as part of a cohesive approach to your document security.
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Differences Between Overt and Covert Document Security Features
First, it’s important to understand the main differences between overt and covert document security features. Think of overt document security features as something out in the open, while covert security features are something hidden.
There are three categories of document security features. Overt is level 1, and it means the public can easily check these documents with the naked eye or with a simple tool.
Covert security features, or level 2, are not readily apparent to the general public. They require a tool, such as a simple magnifying glass or marker pen, to ascertain the validity of the document.
Level 3, which we will not discuss here, involves forensic features that need sophisticated equipment to detect. These get into nano-level particles and other hard-to-see features.
Why You Need Both Overt & Covert Document Security Features
Layered document security serves two purposes: Verification of authenticity and prevention of counterfeiting. A combination of overt and covert document security features, working together, can fulfill both needs.
Overt features can deter casual counterfeiters from attempting to forge documents or currency. Meanwhile, covert features make it difficult for sophisticated counterfeiters to replicate. Combining both types of features and more of them can make it nearly impossible or extremely difficult for counterfeiters to produce documents that pass all security checks.
The more layers you add, the more difficult it is for counterfeiters to win.
Another benefit of both overt and covert document security is that it makes the documents more adaptable. Let’s say a birth certificate has three overt and three covert document security features. Five years from now, a new type of covert item is added to the document thanks to advances in technology. Rather than dispensing with the other security features, which still offer anti-counterfeiting measures, the organization or agency that needs to verify these documents can simply complement the other features already there. They don’t need to redesign the entire document. The agency can add or subtract security features as needed.
Overt Document Security Features
Look at some of the most common overt document security features available. These are easily detectable by ordinary means while providing features that are difficult for the ordinary public to replicate.
DOVID
A diffractive optically variable image device (DOVID) is a sophisticated security feature that utilizes diffraction to create dynamic visual effects. It’s essentially a microscopic grating structure embedded in a material. These effects change as the viewing angle shifts, making them extremely difficult to counterfeit.
DOVIDs are commonly found on passports, banknotes, and other high-security documents. For example, a DOVID on a passport might display a moving image, such as a flag or national emblem, that shifts and changes color as the passport is tilted.
Guilloche
Guilloche is an intricate pattern of fine lines that intersect to create a complex, decorative design. These patterns are typically created using specialized engraving machines. Guilloche is widely used as a security feature on high-value documents, such as banknotes and passports.
For instance, on banknotes, guilloche patterns can be found in the background design, often incorporated with watermarks or holograms to enhance security. On American money, you can see guilloche patterns thanks to the intricate lines around the border, among the letters O-N-E, and around the seal of the United States of America.
Optically Variable Inks (OVPs)
Optically variable inks or optically variable pigments (OVPs) are color-shifting inks that change hues based on the viewing angle. OVPs use a complex structure of layers within the ink, typically with a reflective metallic layer, a transparent dielectric layer, and a translucent metallic layer.
When light hits these layers, it undergoes multiple reflections and interferences, resulting in the color shift observed through ordinary means. The angle at which the light hits the ink determines which wavelengths of light are reflected, creating the color change effect. Because of the multiple layers, it is very difficult to replicate the exact color change on OVPs.
An example is from any modern American currency with a denomination of $10 or higher. In the lower-right corner, the number (10, 20, 50, or 100) changes color when you look at it straight on and then look at it from an angle.
Tactile Laser Engraving
Tactile laser engraving creates raised or recessed patterns on a document’s surface using a high-powered laser. This technique produces physical variations that can be felt by touch, making it difficult to replicate. The process involves directing a laser beam at the document’s material, removing or altering its surface to form the desired tactile pattern. This can create raised elements, indented areas, or a combination of both, depending on the desired effect.
A common example of tactile laser engraving found on documents is the raised inkwell symbol on many American banknotes (which is used in combination with an OVP). This symbol is not only visually distinct but also provides a tactile reference for visually impaired individuals.
Security Thread
A security thread can be both overt and covert. It is typically a very thin piece of plastic film embedded in the layer of the document. Security threads often incorporate multiple document security features, including OVPs, fluorescent dyes, and microprinting, making them even more difficult to replicate.
Hold American currency up to the light. You can see a thin security thread on denominations of $5 and higher. The denomination appears in micro print. The thread changes color when exposed to ultraviolet light.
CLI/MLI
Changeable laser images or multiple laser images (CLI/MLI) are advanced security features used primarily in passports and ID cards. They involve laser engraving multiple images or text layers onto the document’s surface. When viewed from different angles, these images appear to change or shift, creating a dynamic and difficult-to-replicate effect.
For example, you can find this document security feature on a Swedish emergency passport from 2012 that shows the image of the person in the photograph at one angle and then the passport number at a different angle.
Watermark
A watermark is an image on the paper or currency that appears when you hold the paper up to the light. Watermarks are embedded into the paper or cotton itself and are extremely difficult to replicate because of the embedding process. Hold a $100 bill up to the light to see a watermark of Benjamin Franklin.
Paper or Cloth Composition
The composition of the paper or cloth itself can be a deterrent to counterfeiting. The content, weight, thickness, color, and additives to the paper can make it difficult to replicate because of the unique substrate.
Again, back to American currency. If you look closely, you can see red and blue threads randomly dispersed throughout the cotton substrate.
3D Security Ribbons
3D security ribbons often display images or patterns that change appearance as the document is tilted or viewed from different angles. This dynamic effect is achieved through the use of micro-optical structures and special inks. You might see holographic elements, which create iridescent and three-dimensional images that are challenging to counterfeit. Additional security features like micro text, color-shifting inks, and latent images can be integrated into the ribbon to enhance its security level.
Many modern banknotes feature 3D security ribbons that display dynamic images or holographic elements. For instance, the Euro banknotes have a holographic foil strip that changes color and displays a moving image of the euro symbol.
Covert Document Security Features
Now, we will talk about covert document security features. These are detectable with the help of tools that are not ordinarily carried by the public.
Counterfeit Detector Pens
Counterfeit detector pens contain an iodine solution that leaves a mark on the currency. The key is the iodine’s reaction to starch in ordinary paper, which turns black and could indicate a likely counterfeit. The pen mark will turn yellow if the American bill is genuine. Counterfeit detector pens offer a quick way for store clerks to verify genuine currency rather than looking closely at the bills.
Barcodes
Barcodes appear to be black bars and white spaces that represent a series of numbers or characters. The information is encoded based on the specific barcode symbology pattern (UPC, EAN, QR). You need a laser scanner or photographic instrument to read the pattern. The key to verification is the database connected to the barcode scanner. That contains the information that can show the user on a screen what the item is in your hand.
You see these all of the time at registers for retail stores. You can also utilize this technology on your smartphone with the camera. Typical uses in document security include state IDs, passports, property titles, and birth certificates.
Fluorescent Dyes, Taggants, or Inks
Advanced fluorescent dyes, taggants, or inks appear as one color (or even invisible if the ink color precisely matches the substrate color) in the visible light spectrum but then change color when exposed to ultraviolet light. These document security features can be precisely tuned to work only under a certain range of UV wavelengths, meaning even if a counterfeiter knows there is a UV taggant on the document, having the wrong formula or the wrong detector won’t produce the desired result. Typically, handheld fluorescent flashlights or small UV devices are used to detect the fluorescence change.
Some IDs use fluorescence. When exposed to the right wavelengths, hidden features may turn dark or become more prominent. Fluorescence is here to stay because it serves as a backup in case other document security features fail to meet standards or technology breaks down.
Magnetic Stripes or Microchips
Similar to barcodes, magnetic stripes or microchips contain embedded information that require the right kind of reader to interpret the information. The reader is connected to a remote database that contains more information. Examples of this document security feature are everywhere, including on the backs of state IDs, credit cards, and debit cards.
Similar to magnetic stripes, microchips offer a more robust type of security feature that might not be disrupted by a strong magnetic field. The chips are embedded in the card or document, and a reader interprets the data.
RFID Tags
Radio frequency identification (RFID) tags contain a unique identifier, usually embedded in a small tag or on a label. A special reader emits radio waves, which activates the tag when it is within range of the tag. Some tags are only activated at specific frequencies. There is a database attached to the reader that has more information. Typical uses for RFID tags include inventory management and shipments.
Microprinting
Microprinting involves very small print that looks like a line to the ordinary eye. People generally need a magnifying glass to read microprinting. You could see microprinting checks issued by government agencies and on currency. For example, American-issued checks have microprinting that says “USAUSAUSA” on the signature line.
Micro-Controllers
Micro-controllers are small computers embedded on a single integrated chip. Someone can read or scan a micro-controller that encrypts and protects sensitive data on a document. For example, a micro-controller can generate a sequence of random letters and numbers when scanned with one type of device and then a different sequence with another device.
Talk to Angstrom Technologies, Inc., About Our Layered Security Approach
Angstrom Technologies, Inc. has led the industry with advanced fluorescent pigments, dyes, and taggants for decades. Talk to us about your layered document security needs. We can work with your team to develop the right product for you.
Contact us or call 859-282-0020 to start the conversation.
