Digital watermarks, more than just an invisible barcode

FiliGrade is a technology company from Eindhoven in the Netherlands that has developed a patented digital watermarking technology called CurvCode. This innovative system enables the separation of materials from waste streams. FiliGrade introduced the first digital watermarks back in 2016. Two years later, the company succeeded in embedding it on packaging for the first time. CurvCode is based on a special coded curve of points that is embedded in moulds or print. This curve is generally not perceptible to the human eye but is machine-readable.

In waste sorting plants, special cameras and lighting systems are used to identify, capture and decode these codes. Based on this information, the desired material can be sorted correctly. This enables more efficient recycling of the sorted material.

With CurvCode technology, around 1,000 pieces of information can be stored in the code. This focusing simplifies both printing and detection.

The advantage: less data needs to be managed and less computing power is required.  Compared to the Digimarc barcode, the technology offers less at first glance, but is less complex and requires a lower investment for implementation in the sorting systems.

In spring 2023, the sorting of 1 litre Pure-Pak^® cartons with CurvCode was successfully tested with commercial packaging.

Named after the American company of the same name, whose specialty is watermarking, the Digimarc barcode enables digital information to be embedded in physical media such as images, packaging, labels and other printed products in the form of watermarks. Compared to the more focused CurvCode technology, Digimarc barcodes can store an almost infinite amount of information.

Since 2018, netto Marken-Discount has been the first and only retailer in Germany to integrate Digimarc’s digital watermarks on the packaging of its private label food range.

“We initially worked with Digimarc to optimise our checkout, making it easier and more efficient by digitising our PL food and beverage products with Digimarc’s technology,” says netto company spokesperson Christiana Stylianou.

When Filigrade presented its first digital watermarks to Petcore Europe in 2016, the latter’s Managing Director Christian-Yves Crépet commented: ‘Either you’re a charlatan, or this is the Holy Grail.’ This is how the Digital Watermarks pilot project ‘HolyGrail’ got its name. Initially, HolyGrail 1.0 brought together stakeholders from the packaging value chain from 2016 to 2019. As part of this project, various innovative projects in the field of improving post-consumer recycling through the use of chemical tracers and digital watermarks for better sorting were investigated. HolyGrail 2.0 subsequently aimed to enable the technical implementation of digital watermarking for accurate sorting and economic viability on a large scale. The packaging encoded with digital watermarks was to be recognised in a waste sorting system, decoded and sorted based on the transferred attributes (e.g. food vs. non-food). 

After numerous tests and adjustments to the printing and detection technology, detection hit rates of more than 95 per cent are now achieved. In 2023, the first industrial trials with a prototype detection module took place at a recycling plant in Verdun, France. It is planned that a further industrial-scale trial will soon take place at a German sorting plant to ensure a roll-out of both Digimarc and FiliGrade technologies in the near future.

EXTR:ACT was founded in 2018 and is the European platform for increasing the recycling of liquid cartons and similar fibre-based, multi-material packaging. By working together at the European level with the entire value chain, EXTR:ACT helps to ensure that liquid cartons are collected and recycled at competitive costs.

‘For many years now, liquid carton manufacturers have been ensuring the high-quality recycling of their packaging. In doing so, we are always orientated towards the latest possibilities to continuously improve the process in order to meet our own high standards and the stricter legal requirements. This is why we have also carried out corresponding tests and evaluations of digital watermarking (DWM) ourselves via our industry’s own technology organisation EXTR:ACT. We see enormous potential here to achieve the purity and granularity of the sorted liquid cartons (i.e. less “by-catch” in the sorting of liquid cartons), which then contributes to a more targeted supply of the recycling plants for fibres and PolyAl (non-fibre content) with an input quality that in turn leads to high-quality secondary raw materials,’ says Michael Brandl, Managing Director at EXTR:ACT.

Packaging manufacturers who use watermarks on their products in future will benefit in several ways: not only can the yield and quality of the collected liquid cartons be improved and support the entire recycling process. In addition, the companies are once again demonstrating their commitment to environmental protection and resource conservation. Ultimately, this not only has positive effects for the environment, but also strengthens the entire value chain in its ecological endeavours and offers long-term economic benefits.