The Importance of Ink and Paper in Security Printing
As awareness of counterfeit products continues to grow, the importance of ink and paper in security printing has become increasingly evident. Both are essential components of modern anti-counterfeiting systems and play a critical role in preventing document alteration, duplication, and forgery. The following sections discuss their respective functions.I. Inks
Many security inks are designed to indicate document alteration or verify authenticity. Below are several commonly used security inks:1. Chemical-Reactive Inks
These inks react visibly when exposed to erasers, bleaching agents, water, or other chemical solvents, causing fading, discoloration, or staining.Chemical-reactive inks are typically printed in background areas or critical data zones. When used on check data fields, any alteration becomes immediately detectable. Depending on the ink formulation, tampering may cause the ink to disappear, fade, or become visibly contaminated.
These inks are widely used in document protection, particularly for discount and negotiable checks.
Chemical-sensitive inks are evaluated by the ANSI X9B10 Committee and offer strong resistance to document alteration, with approximately 30% protection against erasure and 70% against chemical solvents and bleaching agents.
2. Erasable Inks
Erasable inks provide a clear visual indicator of tampering and are commonly used for background printing. Any attempt to alter printed information results in visible removal of the background pattern.Light or brightly colored solid backgrounds are most effective, as erasure marks are highly noticeable and difficult to reproduce using color copiers. Erasable inks are available in various colors, including fluorescent options.
A typical application is hotel guest checks, where the amount field background is printed with erasable ink. Any attempt to alter the amount by erasing will remove the colored background and reveal tampering.
3. Fluorescent Inks
Fluorescent inks may be invisible under normal lighting but emit light under ultraviolet or infrared illumination. Their covert nature and resistance to accurate reproduction by color copiers make them increasingly popular in security applications.For example, check MICR lines may be printed with fluorescent inks, or entire document areas may contain fluorescent features. Many currencies worldwide incorporate fluorescent inks, which are available in a wide range of colors.
4. Infrared Inks
Infrared inks absorb or reflect infrared light. Information printed or concealed with these inks may be invisible under normal light and readable only under infrared illumination.For instance, infrared black ink can be used to conceal the words "genuine" or "original" which are visible only under infrared light. As with fluorescent inks, proper knowledge and specialized equipment are required for verification.
5. Penetrating Inks
Penetrating inks are commonly used for MICR data on checks. The ink penetrates the paper substrate and becomes visible on the reverse side. By comparing the front and back, altered digits or unauthorized changes can be easily detected.In some applications, invisible fluorescent inks may be added as an additional covert feature.
Penetrating inks are also used on cash receipts to prevent customers from altering transaction amounts and to inhibit unauthorized copying.
6. Thermochromic Inks
Thermochromic inks change color when exposed to body heat or friction and may return to their original color once the stimulus is removed.These inks are used on medical prescriptions to reduce fraud. Typically printed near patient information fields, the ink temporarily disappears when touched.
Color transitions may include blue to colorless or orange to yellow to red. Some thermochromic inks change color permanently when scratched, similar to carbonless coating technology, and may also react chemically to solvents. These inks are widely used on important documents and checks.
II. Paper
Security paper is a rapidly growing segment of the paper industry and plays a vital role in document protection. Many paper manufacturers now offer specialized security papers incorporating the following features:1. Chemical-Reactive Paper
This paper reacts to bleaching agents, rust removers, gasoline, kerosene, paint thinners, and turpentine, causing color changes or revealing warning messages or symbols.2. Security Fibers and Taggants
Paper manufacturers incorporate visible or covert fibers and taggant materials into security paper.Covert materials such as fluorescent fibers are detectable only under ultraviolet light and, like fluorescent inks, cannot be scanned or copied.
3. Toner-Fusion Paper
This paper is designed to bond more effectively with laser printer toner, making printed information difficult to remove or alter.It is particularly suitable for end users who print checks and secure documents using laser printers.
4. UV Dull / UV Dead Paper
UV dull paper removes most fluorescent components, while UV dead paper contains no fluorescent materials at all.Fluorescent ink watermarks printed on these papers appear brighter under ultraviolet light, as the paper itself does not interfere with the fluorescent effect.
5. Watermarks
Various types of watermarks, including dandy roll watermarks, are used in security documents. These are formed during the wet stage of papermaking and are visible from both sides when held up to light.Artificial watermarks, while less costly, are also difficult to reproduce. Some watermarks are printed with fluorescent inks, making them visible under ultraviolet light and enhancing document security.
III. The Future of Security Printing
The effectiveness of security features depends largely on the awareness and proper use by document examiners. Training end users and inspectors to recognize ink- and paper-based security features remains a major challenge for suppliers.Whether through machine verification or manual inspection, combining ink and paper security features is generally more effective than relying on either alone. The greater the number of integrated security elements in a document, the more difficult it becomes to counterfeit.
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