IN Brief:
- Invisible fluorescent tags are being printed onto wrap-around milk-bottle labels used at Arla’s Oakthorpe dairy.
- Polytag readers record tagged packs at participating materials recovery facilities and transfer barcode-level data to a dashboard.
- Saica Flex prints the labels, while Sun Chemical supplies ink tested for recycling compatibility.
Aldi UK and Arla Foods have started an operational trial using invisible ultraviolet tags on milk-bottle labels to measure how packaging moves through the recycling system after sale.
Fluorescent ink is being printed onto wrap-around labels used on Arla’s milk range at its Oakthorpe dairy. Saica Flex produces the labels, Sun Chemical supplies the specialist ink, and Polytag operates the detection platform that records tagged packs as they pass through participating materials recovery facilities.
The partners say the system can produce barcode-level recycling data without reducing line speed or occupying visible label space. Detection units installed at sorting facilities read the mark and transfer each event to Polytag’s dashboard, giving the retailer and dairy producer a record of where and when tagged packaging has been observed.
The project builds on an Aldi trial conducted in 2023 using pressure-sensitive labels. Moving the tag onto a wrap-around format brings the work closer to high-volume dairy production, where label materials, printing, application, filling speed, and recycling behaviour have to be considered as one packaging system.
Traceability moves beyond the factory gate
Milk bottles are already a comparatively mature recycling format in the UK, but producers and retailers still have limited direct evidence about what happens to individual packs after household collection. Sales volumes and local authority statistics can estimate performance; they do not show whether a particular labelled bottle reached a facility equipped to sort it.
UV tagging is intended to close part of that gap. The food-safe fluorescent ink is applied through conventional printing methods and remains invisible during normal use. When the pack reaches a detection unit, the system records the tag without requiring a consumer to scan a code or return the container through a dedicated deposit machine.
Consumer-facing digital labels can support instructions and engagement, but participation varies and a scan does not prove that packaging reached a recovery facility. Facility-level detection produces a different record: an observed event within the waste stream, linked to the packaging identity carried by the printed mark.
The trial also tests whether the ink and label structure can be incorporated into routine production without creating another bottleneck. Dairy filling operations run at high speed, and even a modest reduction in label application reliability can cause stoppages, rework, or rejected packs. The partners say the ink can be applied using standard printing methods without affecting production speed.
Recycling compatibility is equally important. Sun Chemical says the ink has performed satisfactorily against RecyClass washing procedures and the European PET Bottle Platform’s QT 507 quick test. The companies also state that the mark does not impair recovered polymer quality, although the current trial is designed primarily to examine detection and data rather than prove the full recyclability of the bottle system.
Coverage will determine the data’s value
The commercial output is evidence that can influence packaging specifications and investment. Aldi and Arla could compare detection by product, period, location, or label format, identify where packaging disappears from the observed stream, and test whether design changes are associated with measurable differences in recovery.
Detection units do not cover every UK sorting facility. A bottle that is not scanned may have been handled by an uninstrumented plant, exported, rejected before the reader, or disposed of outside household recycling. The dataset therefore measures activity within the installed network rather than producing a complete national recycling rate.
Useful interpretation requires separation between the number of tags placed on the market, the proportion entering monitored facilities, successful reads, duplicate events, and the final treatment of the material. A large volume of scans can otherwise be mistaken for a recycling outcome that the system has not verified.
The trial involves several companies because no single participant controls the entire chain. Arla manages dairy production and label application, Saica Flex converts the label, Sun Chemical formulates the ink, Aldi places the packaged product on the market, Polytag manages identification and detection, and recovery operators provide the physical point at which data is captured.
That structure mirrors the wider challenge facing packaging compliance. Producers are being asked to substantiate recyclability and recovery claims while depending on converters, material suppliers, local collection systems, sorting infrastructure, and recyclers. Digital traceability can improve visibility only when identifiers survive production and use, detection coverage is understood, and the resulting records are accepted by commercial and regulatory stakeholders.
The operational phase should show whether the tags remain readable through routine manufacturing, retail handling, household use, collection, and sorting. The strongest result would not be a single recycling percentage, but a repeatable method linking packaging placed on the market with observed movement through real facilities at sufficient scale to guide specifications.
The trial carries packaging data one step closer to the physical waste stream. Routine adoption will depend on detection consistency, network coverage, integration cost, and the quality of decisions made from the records — less visible than the fluorescent ink, but considerably more important.