How invisible codes are transforming premium packaging

The code becomes invisible

Instead of large, visible blocks, this information is now integrated directly into the graphics, making it invisible to the human eye. The encoding process begins long before printing, in the pre-press department. Rather than placing an isolated barcode on the packaging, the software encodes the design itself. This is based on digital watermarking, often implemented using the Digimarc DWCode.

Plug-ins in the design software overlay the entire artwork with a fine, contrasting grid that is imperceptible to the human eye. The software shifts the brightness and colour values of the image pixels at a microscopic level to create a redundant data pattern.

Shoppers in the shop see a flawless, unspoilt design. For optical sensors and cameras, the entire surface within a 360-degree radius becomes a data carrier. Every square centimetre of the paper carries the Global Trade Item Number (GTIN) and an encrypted web URL. This saves space on the physical material, as brand manufacturers store legally required information digitally. In this way, they reclaim valuable space on the physical material, as legally required information can be transferred to the digital realm.

Production on the shop floor

Once approved, the data is sent to the print shop. The sleeve is printed on sheet-fed offset presses. The process also works on analogue flexographic printing presses or high-speed inkjet systems.

The invisible watermark is based on minimal differences in contrast. The printing process tolerates virtually no deviations here:

• Dot gain: When liquid ink comes into contact with open-pored uncoated paper, it spreads capillarily along the fibres. If this dot gain deviates even slightly from the target value, the micro-fine contrast patterns become blurred. They become unreadable to cameras.
• Absolute register accuracy (registration): Multi-coloured lines must align perfectly with one another to within the micrometre range. Even a registration deviation of 20 micrometres corrupts the halftone pattern.

To rule out such errors, printing companies monitor the process using in-line inspection systems. High-performance cameras scan each sheet in real time. Algorithms monitor the printed image and correct registration and colour errors immediately.

The chocolate brand in our example prints without using plastic-based UV inks. The wrapper uses bio-based soya inks or carbon-negative algae inks such as Algae Black. These inks are almost entirely free of volatile organic compounds (VOCs) and do not interfere with subsequent recycling.

Logistics and Point of Sale

Once printed, cut and packaged, the chocolate is sent to the retailers’ logistics centres.

This is where the first operational advantage comes into play. Conventional packaging must be rotated on the conveyor belts so that sensors can detect the barcode. The logistics camera captures the digital watermark in a fraction of a second, regardless of which way round the product is lying on the belt or whether it is crumpled. This speeds up the flow of goods and ensures track-and-trace processes.

A short while later on the supermarket shelf: a customer picks up the chocolate, drawn in by the elegant look of the unadorned design. At the supermarket’s self-service checkout, there’s no need to search for the barcode. A quick swipe over the image scanner is all it takes to register the product.

Once home, the packaging becomes an interactive portal. Using her smartphone, she scans the chocolate wrapper and, via the GS1 Digital Link – a smart successor to the QR code that connects physical products directly to the web – the Digital Product Passport (DPP) opens. It shows which Ecuadorian cooperative the cocoa beans come from, documents the production’s carbon footprint and provides additional content such as a matching playlist to enjoy whilst relaxing with the chocolate.

Unlike active smart packaging concepts, which rely on conductive inks or printed electronics, the watermark operates passively. It transmits data without driving up material costs. 

Disposal and circular processing

Once the chocolate has been enjoyed, however, our stylish packaging also ends up in the waste paper bin. At the recycling sorting plant, the watermark helps to increase the recycling rate. This technology forms the basis of the European HolyGrail 2.0 initiative. As the waste paper (and indeed the waste plastic from packaging coded in this way) passes along the high-speed conveyor belts, cameras detect the invisible pattern. The system reads the material data – in this case: single-material paper, bio-based ink – and uses a jet of air to blow the wrapper precisely into the correct recycling stream, rather than leaving it in the mixed waste.

In industrial de-inking, the choice of bio-based inks comes into play:

• In the pulper, the soya or algae-based ink is separated from the cellulose fibres without leaving any residue through mechanical shear forces.
• In the flotation tank, the hydrophobic ink particles adhere to fine air bubbles. They rise to the surface as foam and can be skimmed off.
• Unlike UV acrylate inks, they leave behind neither sticky plastic particles nor a grey haze in the water.

The recovered cellulose fibres retain their strength and brightness. They are fed straight back into the production of high-quality cardboard.

The intersection of design and data

The journey of our chocolate shows that modern security printing and smart product labelling are no longer isolated disciplines. They form the indispensable interface where aesthetics, legal requirements (such as the Packaging Act and the EU Ecodesign Directives) and technological progress complement one another.

By combining data expertise with physical printing excellence, printers and brand owners are resolving the previously intractable dilemma between maximum information content and a flawless, sales-boosting visual appearance. Packaging is no longer merely a protective covering. It manages the logistics flow, informs the buyer and, ultimately, organises its own recycling.