When it comes to printing important documents like banknotes, ID cards, tax stamps and other highly secure items, there is no room for error. Even the slightest flaw or lack of sophistication in the printing process could potentially enable counterfeiting. That’s why the world’s government agencies, financial institutions and security printers invest heavily in high-security printing techniques that leverage specialized inks, papers and processes to protect against fraud.
At the cutting edge of high-security printing are optical security features created using advanced pigments and chemical compounds that are undetectable to the naked eye. These include ultraviolet (UV) and infrared (IR) pigments that enable sophisticated anti-counterfeiting capabilities when the right inspection tools are used.
The Power of UV and IR Pigments
UV and IR pigments have become a critical line of defense in ensuring only legitimate printed items can pass inspection. These pigments are formulated to absorb, reflect or emit specific wavelengths beyond the visible spectrum that standard printing inks cannot reproduce.
Some common uses of UV/IR pigments include:
UV-Dull Papers
These papers are designed with UV brightening agents that cause them to naturally fluoresce under UV light. However, the UV pigments used can dull or color-shift this fluorescence in a pattern that is extremely difficult to counterfeit without using the exact same pigments.
UV Fibers
Invisible to the naked eye, UV fibers embedded in paper and inks will fluoresce under UV light as an authentication feature. The UV fibers can even be formulated with different glows, colors and brightnesses.
UV Reagent Inks
UV reagent inks are formulated to remain transparent and invisible until activated by being exposed to a laser, LED or other UV radiation source. Once activated, they will undergo a chemical reaction and become visible as a color shift or fluorescence.
IR Pigment Tagging
IR pigments can be used similarly to their UV counterparts as taggants by incorporating them into the ink itself. They remain invisible until being authenticated with an IR light source.
Beyond just UV and IR, manufacturers of high-security inks have developed a wide array of optically variable pigments (OVPs) and other sophisticated compounds to fight counterfeiting. Examples include optically variable magnetic pigments, up-conversion ink, metallic anti-copier solution, photochromic inks that change color when exposed to UV light, and thermochromic ink that changes color with heat differential.
The use of these advanced optical security inks requires specialized printing equipment, proprietary pigment suppliers, and highly controlled processes. Only extremely sophisticated counterfeiters would have a chance at accurately reproducing items printed with today’s cutting-edge anti-counterfeiting techniques.
Lasting Quality and Stability
In addition to being difficult to reproduce, secure inks must offer long-term stability and quality. That’s why the pigments used in optical security printing undergo extensive testing to ensure color permanence, durability, and consistency over decades of use. Many high-security applications require up to 20 years of life for the printed item.
The rigorous performance standards for security printing inks demand advanced chemical formulations that resist fading, abrasion, UV exposure, chemical tampering and other potential degradation over the usable life of the printed item. This is another major hurdle for counterfeiters, requiring extensive development and testing to mimic the performance of legitimate secure printing inks, papers and production processes.
As counterfeiters continue to improve their capabilities, government agencies and security printers remain diligent in their quest to stay one step ahead. The ongoing development and integration of new ink chemistries and optical security features will help ensure the world’s most valuable printed items retain the highest levels of authentication and counterfeit protection.