What is an IR‑Reactive Ink? Machine‑Readable Security
IR‑reactive ink (infrared reactive ink) is a type of covert security ink that is invisible or barely visible to the naked eye but absorbs or reflects infrared (IR) light in a specific way, making it readable by IR cameras, sensors, or banknote sorting machines. Unlike UV‑reactive ink (which glows visibly under UV light), IR ink is designed for machine‑readable authentication – automated verification without human intervention. It is commonly used on banknotes, passports, tax stamps, and high‑security product labels where high‑speed, contactless verification is required. IR inks can be formulated as IR‑absorbing (appear dark under IR light) or IR‑transparent / reflective (appear bright under IR light), creating contrast that cameras can detect. Because IR features are invisible to counterfeiters and require specialised readers, they provide a strong second line of defence when combined with overt holograms.
At Holoseal – a trusted hologram supplier with 15+ years of experience – we integrate IR‑reactive inks into custom hologram labels, strips, and foils. Our IR features can include machine‑readable codes, batch numbers, or hidden patterns that can be read by standard IR cameras (700–1000 nm). We serve clients across India and worldwide for central banks, government mints, and high‑security brand protection programmes.
🔍 How IR‑Reactive Ink Works
IR‑reactive inks contain special pigments or dyes that have a unique response to near‑infrared (NIR) light, typically in the 700–1000 nm wavelength range (invisible to the human eye). There are two main types:
- IR‑absorbing (carbon‑based) – The ink appears black or dark when illuminated with IR light because it absorbs the IR radiation. This creates a high‑contrast pattern against a reflective background (e.g., paper or metalized film).
- IR‑transparent / IR‑reflective – The ink allows IR light to pass through or reflects it, appearing bright under IR illumination. Often used for hidden codes printed over a dark background.
An IR camera or sensor detects these differences and converts them into a digital signal, which can be used to read barcodes, verify logos, or authenticate the item.
🛡️ Applications of IR‑Reactive Ink on Hologram Labels
- Machine‑readable serial numbers – IR‑printed numbers that are invisible to the eye but can be scanned by cameras during logistics.
- Hidden barcodes (Code 128, Data Matrix) – For automated sorting and track‑and‑trace without visible codes on the packaging.
- Banknote denomination codes – IR patterns that sorting machines use to identify the value and authenticity of a note.
- Tax stamp authentication – Customs officers use handheld IR viewers to verify excise stamps without opening cartons.
- Pharmaceutical serialisation – IR‑printed batch numbers that can be read at distribution centres but are invisible to patients.
- Anti‑diversion marks – Hidden IR codes that prove the intended market of a product (e.g., “For India Only”).
⚙️ How IR Ink Is Applied to Hologram Labels
- The hologram label is produced (embossed, metalized, and optionally overprinted with overt colours).
- IR‑reactive ink is printed using flexography, gravure, or digital inkjet in the desired pattern (e.g., a barcode or logo).
- The ink is cured (dried) – carbon‑based IR inks are typically solvent‑based and require heat drying.
- Quality control: An IR camera verifies that the pattern has the correct contrast and is readable by sensors.
🔐 IR‑Reactive vs. UV‑Reactive vs. Overt Hologram
- Overt hologram – Visible to naked eye; tilt for rainbow colours. Consumer verification.
- UV‑reactive ink – Glows under UV lamp. Human‑readable covert feature (inspector with light).
- IR‑reactive ink – Invisible; requires IR camera or sensor. Machine‑readable, high‑speed automated verification.
📦 IR‑Enhanced Products We Supply
- IR‑printed hologram labels – Custom hologram labels with hidden IR barcodes or serial numbers.
- IR‑reactive security strips – Narrow strips for banknotes, passports, or tax stamps with machine‑readable features.
- Combination UV + IR hologram labels – Two different covert features: one visible under UV lamp, the other only to IR cameras.
- Laser‑demetalized + IR – Demetalized QR code (visible) and an IR‑printed batch code (invisible) on the same label.
- Custom IR pattern design – We help you design IR patterns optimised for your specific sensors (wavelength, contrast).
🏭 Industries Using IR‑Reactive Ink
- Central banks (banknotes) – High‑speed sorting and authentication; IR features are mandatory for modern currency.
- Tax stamps (alcohol, tobacco) – Automated verification at borders using handheld IR readers.
- Pharmaceuticals – IR‑printed serial numbers for warehouse scanning without visible labels on retail packaging.
- Automotive & aerospace – Hidden IR part numbers for supply chain traceability.
- Government documents (passports, visas) – IR features on data pages that are read by e‑gate scanners.
- High‑value brand protection – Invisible codes for investigators to authenticate products in the field.
🕵️ How to Verify IR‑Reactive Features (For Inspectors)
- Obtain a handheld IR viewer or IR camera (many smartphone‑attached IR viewers are available). Alternatively, a banknote sorting machine can be used.
- Illuminate the label with IR light (e.g., 850 nm or 940 nm LED).
- View the label through the IR camera. Genuine IR‑absorbing ink will appear dark against a bright background; IR‑transparent ink will appear bright against a dark background.
- The expected pattern (barcode, logo, or text) should be clearly visible and readable.
- If no pattern appears or the contrast is poor, the label may be counterfeit.
🌍 Holoseal’s IR‑Reactive Capabilities
We partner with specialised security ink manufacturers to source IR inks that are compatible with holographic substrates. For clients in Mumbai, Delhi, Bengaluru, Chennai, Hyderabad, Pune, Ahmedabad, Kolkata, Surat, Kochi, Jaipur, Lucknow, Nagpur, Indore, Vadodara, Ludhiana, Patna, Guwahati, Chandigarh and worldwide, we supply IR‑enhanced hologram labels, strips, and foils. With 15+ years of experience, we advise on the correct IR ink type (absorbing vs. transparent), wavelength compatibility (850 nm, 940 nm, etc.), and integration with your existing scanning infrastructure.
❓ Frequently Asked Questions About IR‑Reactive Ink
Can I see IR ink with my naked eye?
No – IR ink is formulated to be invisible or very faint under normal light. Specialised IR cameras or viewers are required.
Is IR ink the same as thermal ink?
No. Thermal ink changes colour with heat; IR ink changes its reflection/absorption of infrared light but is not temperature‑sensitive.
Can a smartphone camera see IR ink?
Most smartphone cameras have an IR filter that blocks IR light. However, some phones (without strong filters) can see very near IR if the IR LED is bright, but it’s not reliable. Dedicated IR viewers are recommended.
Is IR ink durable?
Yes – IR inks can be formulated to be abrasion‑resistant and solvent‑resistant. For outdoor or harsh environments, we recommend a protective top coat.
What is the difference between IR‑absorbing and IR‑transparent ink?
IR‑absorbing ink looks dark under IR light; IR‑transparent (or reflective) ink looks bright. Both are used to create contrast patterns. The choice depends on the background (e.g., paper vs. metalized film).
How to order IR‑enhanced hologram labels from Holoseal?
Specify the hidden pattern (e.g., “Data Matrix code with serial numbers”), the IR response type (absorbing or transparent), label design, and quantity. We will produce a sample and test it with an IR camera before mass production. Contact us for a quote.
