Tracer and Anti-Counterfeiting Additives: 5 Marker Types, Mechanisms, Dosage and Selection

Tracer additives are markers dosed into a plastic at around 100 ppm, roughly one part in ten thousand, purely so that a machine can recognise the object later, either on a sorting line or in a counterfeit check. That is a strange job for an additive, because it has to be detectable and otherwise invisible, so which chemistries manage both? The 2022 review in Polymers by Olscher, Zafiu and colleagues at TU Wien and the Umweltbundesamt answers quantitatively: about 100 ppm (0.01 wt%), with lanthanide-doped oxide markers changing no mechanical property of polypropylene or ABS up to 250 ppm (0.025 wt%).

Five marker classes carry the function here, in the order used throughout this page: up-conversion oxides such as Y2Ti2O7:Yb,Er, down-shifting phosphors such as europium-doped yttrium oxysulfide (Y2O2S:Eu3+), rare-earth oxides read by X-ray fluorescence such as cerium(IV) oxide and yttrium(III) oxide, organic fluorophores such as the perylene pigment PTCDA and the optical brightener BBOT, and covert identity markers such as DNA and molecular markers, quantum dots and particle fingerprints. The technology most often confused with all 5, the digital watermark of the HolyGrail 2.0 programme, is not an additive: it is an imperceptible code printed on a label or embossed into the mould.

This page settles the vocabulary, explains what near-infrared sorting cannot resolve, sets out the 4-step read sequence, classifies the 5 marker types with their evidence, names the polymers and applications that carry a marker, fixes the ppm window, gives 6 selection steps, attributes the performance metrics, and works through the EU food-contact position built on the Annex II lanthanide sum limit of 0.05 mg/kg.

The 5 marker types differ in the radiation that excites them, in whether they survive a black host, and in how much in-polymer evidence exists for each.

Concentrations in this table are tested research levels, not supplier recommendations. No producer datasheet for a tracer grade is held in this reference.

What Is a Tracer Additive in Plastics?#

A tracer additive is a marker substance compounded into a plastic at parts-per-million level that gives the object a machine-readable fingerprint, so a sorting line or a brand inspector can identify it without any change to how the plastic performs. Which machine is doing the reading, and what is it looking at? Two readers dominate the published record: a photodetector watching for light the marker emits under a defined excitation, and an X-ray fluorescence head reading which elements are present. Among plastic additives this is an unusual specification, because 3 uses follow from one capability rather than from a property: tracer-based sorting in recycling, anti-counterfeiting and brand protection, and recycled-content verification and traceability.

The family sits at the far edge of what an additive normally does. Tracers are 1 of the 43 families of plastic additives catalogued in this reference, and the specification is a detection event rather than a property value. Nothing in this record describes routine commercial use at scale: it holds pilot and demonstration projects, university trials and the product lines of 2 sorting-technology companies.

Tracer, marker or taggant: which term is correct?#

All three words name the same thing, a substance put into a plastic to be found again, and the vocabulary simply follows the industry, with recycling research saying tracer, brand protection saying taggant, and both saying marker. The recycling literature calls the whole process tracer-based sorting, a term used by the INEC institute at Pforzheim University, by Woidasky and colleagues at KIT, and by the TU Wien review of 2022, and it names the process rather than the substance.

Brand protection inherited a different word. A taggant is a covert additive whose presence proves origin, and the same chemistries appear there as in sorting: fluorescent and infrared-active pigments, DNA and molecular markers, and particle systems. Nothing in this reference separates taggant chemistry from tracer chemistry, so anti-counterfeiting markers and sorting tracers are one family with two jobs, and the choice of word predicts the reader rather than the molecule.

What actually differs between the two jobs is the specification, not the chemistry, as the table sets out across 7 criteria.

Why a Plastic Needs a Machine-Readable Fingerprint#

A sorting line has to answer a question the material itself does not contain: not which polymer this is, but where this object came from and where it is allowed to go next. Regulation (EU) 2022/1616 on recycled plastics, in force since 10 October 2022, treats post-consumer mechanical PET recycling as a suitable technology with a maximum of 5 % non-food input. A polypropylene tub carries no spectroscopic record of whether it once held yoghurt or engine degreaser, and design for recycling cannot add one afterwards.

Regulation (EU) 2025/40, the Packaging and Packaging Waste Regulation, pushes in the same direction by setting minimum post-consumer recycled content for 4 packaging classes from 2030. Sortability is one of the decisions covered by design for recycling, and a marker is the one additive whose whole purpose is to make that decision readable by a machine. No instrument in this reference requires, recognises or names a tracer additive; the law sets the demand for identity, not the method.

What near-infrared sorting can and cannot tell apart#

Near-infrared sorting reads the polymer's own absorption spectrum, so it separates PET from PP reliably, tells two PP tubs apart not at all, and goes blind completely when carbon black absorbs the light it needs. Carbon-black-pigmented plastics absorb near-infrared radiation and cannot be sorted by a conventional NIR sorter, which is why NIR-detectable and infrared-reflective blacks exist.

Three cases resist a near-infrared sorter, and a marker answers each of them.

• Same polymer, different history, such as a food-grade PP tub and a chemically identical non-food PP tub, because both return the same spectrum.
• Black and dark articles, because carbon black absorbs the interrogating beam before the polymer can return a usable signal.
• Multilayer and sleeved articles, because the sorter reads the outermost material rather than the body of the object.

The pigment-side answer is a class of NIR-sortable black colorants: Ampacet describes its REC-NIR-BLACK grade as COTREP-certified for PP and HDPE, and Shepherd Color supplies an infrared-reflective black. That route restores visibility to the existing sorter without adding a code, while a tracer supplies an identifier independent of the polymer spectrum.

How does a sorting line read a tracer? Excitation, detection and ejection#

A tracer is read in 4 steps: the object passes a radiation source, the marker absorbs that energy and emits light at its own wavelength, a detector assigns the object to a class, and an air jet ejects it into the right stream.

1. Excite the marker with a defined source. Woidasky and colleagues at KIT and Pforzheim, in the MaGiQ project of 2020, used 980 nm excitation at up to 10 W/cm² on up-conversion markers in HDPE film.
2. Collect the emission at the marker's own wavelength. Up-conversion markers emit visible light under that near-infrared excitation, which separates signal from illumination.
3. Classify the object from the signal. X-ray fluorescence classifies by element instead of emitted colour, works in air above atomic number 29, and already ejects PVC through its chlorine and brominated flame-retardant plastics through their bromine.
4. Eject the classified object with an air jet into its stream.

Where the marker sits changes nothing about those 4 steps and everything about the compounding route: Larder and Hatton, reviewing photoluminescent labels in ACS Polymers Au in 2022, group the options into extrusion into the polymer, a coating and a printed label. Up-conversion and X-ray fluorescence are the 2 leading detection routes in that literature, Raman spectroscopy is untested for tracer-based sorting, and lanthanide supply risk constrains any rare-earth route. No belt speed, throughput, detector model or read distance is established here.

5 Types of Tracer and Marker Additives for Plastics#

Marker additives for plastics fall into 5 types: up-conversion lanthanide phosphors, down-shifting lanthanide phosphors, XRF-detectable rare-earth oxides, organic fluorescent markers, and the covert identity markers used for brand protection. The order runs from the chemistry with the most published in-polymer data to the one with the least, and it repeats in every table, list and image on this page.

Evidence depth sets it: only the up-conversion class has been tested at 3 concentrations in a real film, only the organic class has substance records and food-contact entries here, and the covert class is named without a published concentration.

1. Up-conversion lanthanide phosphors (near-infrared excitation)#

Up-conversion phosphors are lanthanide-doped oxides that absorb 2 near-infrared photons and emit 1 visible photon, which is the property that lets them be read inside black plastic where near-infrared sorting fails. The composition named in this reference is Y2Ti2O7 doped with 2 % Yb3+ and 1 % Er3+, in which ytterbium is the sensitiser that absorbs the incoming photons and erbium the activator that emits. No CAS number exists here for a composition of this kind, because the material is a doped ceramic rather than a single registered substance.

The in-polymer evidence comes from one project. Woidasky and colleagues at KIT and Pforzheim University tested Yb3+-sensitised oxides with Er3+, Ho3+ or Tm3+ activators at 10, 100 and 1,000 ppm in HDPE film in several colours including black, under 980 nm excitation at up to 10 W/cm², and published the work in Resources, Conservation and Recycling in 2020. That result describes extruded film rather than injection-moulded wall thicknesses, and it is a single project, so the black-HDPE finding carries the name of the study that produced it.

2. Down-shifting lanthanide phosphors (ultraviolet and visible excitation)#

Down-shifting phosphors work the ordinary way round, absorbing ultraviolet or visible light and emitting at a longer wavelength, and the composition named in this reference is europium-doped yttrium oxysulfide, Y2O2S:Eu3+. Europium is the activator, the yttrium oxysulfide host carries it, and the emission sits in the visible red, which makes the class readable with conventional ultraviolet excitation rather than the high-power infrared source an up-conversion marker needs.

The record for this class stops at the chemistry. No in-polymer concentration, host polymer, CAS number or food-contact entry for Y2O2S:Eu3+ is held in this reference, and the up-conversion numbers do not transfer, because they were measured on a different absorption mechanism in a different host. What the literature supplies is the place of the class: Larder and Hatton in 2022 sort photoluminescent labels into ultraviolet-visible organic, ultraviolet-visible inorganic and infrared up-conversion families.

3. XRF-detectable rare-earth oxide markers#

XRF markers are rare-earth oxides such as cerium(IV) oxide (CAS 1306-38-3) and yttrium(III) oxide (CAS 1314-36-9) that answer by element rather than by colour, which is why X-ray fluorescence already ejects PVC and brominated plastics on industrial lines. X-ray fluorescence in air detects elements with an atomic number above 29, excluding the light elements of the polymer backbone and including every lanthanide, so the marker signal sits where the host contributes nothing.

Both oxides appear in the 2022 Polymers review as candidate tracers rather than commercial grades. Cerium(IV) oxide is registered under REACH at more than 1,000 tonnes per year and is not classified under GHS, and yttrium(III) oxide is registered at more than 100 tonnes per year, but those bands describe registration for all uses, not production of a marker product. Two consequences follow from reading by element: the result is colour-independent, so a black article is no harder to classify than a natural one, and the detector hardware already in use on chlorine and bromine can in principle carry a deliberate rare-earth code.

4. Organic fluorescent markers and optical brighteners#

Organic fluorescent markers are dye-type molecules read under ultraviolet light, and the one already used this way in plastics is the optical brightener BBOT (CAS 7128-64-5), whose own record names it a UV tracer as well as a whitening agent. BBOT, 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, has the formula C26H26N2O2S and a molar mass of 430.6 g/mol, is sold as Tinopal OB by BASF and Benetex OB by Mayzo, and absorbs ultraviolet light to re-emit blue fluorescence. The candidate named in the 2022 review for the same class is the perylene pigment PTCDA, with a predicted melting point above 500 °C and no CAS number here.

This is the only one of the 5 classes with a food-contact file. BBOT is FCM No 500 in Regulation (EU) No 10/2011 with an SML of 0.6 mg/kg, and 21 CFR 178.3297 lists it at up to 0.015 % under conditions A to H or 0.05 % for the listed food types. The stilbene brightener OB-1 (CAS 1533-45-5) is FCM No 422 with an SML of 0.05 mg/kg carrying note (2), the warning that the limit can be exceeded in fatty simulants, and 21 CFR 178.3297 allows up to 0.025 % by weight at temperatures not exceeding 275 °F (135 °C). The tracer function is narrow: BBOT serves as a coverage tracer checked under black light.

5. Covert identity markers: DNA, molecular, quantum-dot and particle fingerprints#

Covert identity markers answer a harder question than a sorting tracer, because the code has to be unique or unforgeable, and the routes named in this reference are DNA and molecular markers, quantum dots, 13C isotopic labels and randomly distributed particle fingerprints. An authentication code has to survive an attempt to copy it, and that requirement pushes the chemistry towards signals that are either secret or irreproducible.

The particle fingerprint is the one system described in concrete terms. Polysecure, in Freiburg, markets TrackByStars, in which randomly distributed fluorescent particles form an individual code that a reader records and compares, alongside its Sort4Circle multisensor sorting. Everything else in this class is recorded as a route rather than a product: brand protection for caps and closures, automotive spare parts and medical devices uses covert fluorescent or infrared pigments and DNA or molecular markers, and this reference holds no concentration, grade, trade name or verified vendor for any of them.

Which Plastics and Applications Carry a Tracer?#

A tracer belongs on any object whose next owner is a machine: food-grade packaging that has to be separated from identical-looking non-food packaging, branded parts that have to prove they are genuine, and material that has to carry a recycled-content claim. Polypropylene, HDPE and PET dominate the sorting cases, because they dominate the packaging streams food-contact recycling law treats separately, while the brand-protection cases name no polymer.

Food-grade packaging: PP, HDPE and PET#

Food-grade recycling is where the demand for markers is sharpest, because Regulation (EU) 2022/1616 allows post-consumer mechanical PET recycling only with at most 5 % non-food input, and nothing in the polymer itself records whether a tub once held food. Adopted on 15 September 2022 and in force since 10 October 2022, it replaced Regulation (EC) No 282/2008 and recognises 2 suitable technologies, post-consumer mechanical PET recycling and closed product loops, with the PET output excluded from microwave and oven applications. The materials, limits and additive choices for this sector are set out under additives for food packaging.

The UK PRISM project is the worked example. Nextek, Brunel University, Tomra, CCL, Mirage Inks, Johnson Matthey, ELR, Cleantech Europe and WRAP developed luminescent coded labels, made in part with phosphors recovered from lamp recycling, to sort food-grade PP, HDPE milk bottles and sleeved PET. The input rules those labels serve are set out on recycled plastics regulations. Nothing in Regulation (EU) 2022/1616 permits, recognises or requires a marker: a tracer is one way a recycler might evidence input origin, not a method the text names.

Brand protection: caps, spare parts and medical devices#

Brand protection asks the opposite question from sorting: not which stream an object belongs to, but whether this particular object came from the right factory, which is why the markers used for it are covert and the codes are meant to be unforgeable. Anti-counterfeiting means, in the plastics sense, a feature a genuine manufacturer can prove and a copier cannot reproduce, whether an additive in the polymer, a pigment in a decorative layer or a particle pattern read by a dedicated device.

Three end uses are named in this reference: caps and closures, automotive spare parts and medical devices. Counterfeit devices are one reason additives for medical plastics are specified so closely, and laser-markable additives sit beside this family as the sibling route to a human-readable mark. No anti-counterfeiting additive product, brand or vendor is documented here, so none is named.

Recycled-content and traceability claims#

The third job for a marker is proof: from 2030 the PPWR sets minimum post-consumer recycled content of 30 % for contact-sensitive PET packaging and 10 % for contact-sensitive non-PET packaging, and a claim that large invites the question of how it is verified. Regulation (EU) 2025/40 was published in the Official Journal on 22 January 2025 and applies from 12 August 2026, and its Article 7 adds 30 % for single-use plastic beverage bottles and 35 % for other plastic packaging in 2030, rising in 2040 to 50 %, 25 %, 65 % and 65 %. Those targets come from the Packaging and Packaging Waste Regulation rather than from any rule about markers.

A parallel obligation runs through product data rather than the material: the Ecodesign for Sustainable Products Regulation, Regulation (EU) 2024/1781 of 28 June 2024, tracks substances of concern through the Digital Product Passport, and the PPWR uses the same definition. Whether a marker can serve as evidence for a recycled-content claim is not established here: the demand for verifiable identity is documented, the acceptance of tracers as the method is not.

How Much Tracer Does a Compound Need? Dosage, the ppm Window and Masterbatch#

The published window for a sorting marker is about 100 ppm, which is 0.01 wt%, with tested levels running from 10 ppm to 1,000 ppm and a measured ceiling of 250 ppm below which lanthanide-doped oxides changed no mechanical property of polypropylene or ABS. Both figures come from the 2022 Polymers review by Olscher, Zafiu and colleagues, which leaves a factor of 2.5 between the recommended level and the highest level tested without a property penalty.

Every value here comes from a study or from a supplier datasheet written for a different purpose. None is a tracer-grade dosage recommendation.

Dosing 100 ppm directly into an extruder is not practical, which is why a marker at this level is dosed as a concentrate during plastic compounding. A 1 % marker concentrate let down at 1 % gives 100 ppm in the part, so the concentration chosen for the carrier decides how accurately a gravimetric feeder holds the level at the die.

Feeding accuracy matters more here than in most additive families, because the acceptance criterion is a detector threshold rather than a property curve, and nothing here fixes that threshold for a commercial line.

The conversion from concentrate to 100 ppm in the finished part is what the let-down ratio calculator does. No price per kilogram for a marker or a concentrate exists in this reference, so cost in use cannot be calculated from these levels.

How Do You Select a Tracer Additive? 6 Steps#

Select a tracer in 6 steps: decide what the code has to prove, match the detection route to the equipment that will read it, choose whether the marker goes in the polymer or on the label, check the host colour, screen the food-contact position first, then set the level near 100 ppm and confirm it on the line.

1. Decide the job before the chemistry: a sorting code separates classes, an authentication code has to be unforgeable, a traceability code has to survive an audit.
2. Match the detection equipment at the reading point. Up-conversion and XRF are the 2 routes with published results, XRF needs an element above atomic number 29 in air, and Raman spectroscopy is untested.
3. Choose where the marker sits: extruded into the polymer, in a coating, or printed on a label, the 3 routes reviewed by Larder and Hatton in 2022.
4. Check the host colour. Up-conversion markers have been read in black HDPE film, XRF is colour-independent, organic fluorophores suit clear or light material.
5. Screen the food-contact route in every target market first, because the EU limit for the 4 listed lanthanides is a sum of 0.05 mg/kg.
6. Fix the level near 100 ppm, verify property neutrality against the 250 ppm result, and confirm detection on the equipment that will run it.

A formulator should treat steps 5 and 6 as the gate rather than the finish, because a failure at 0.05 mg/kg cannot be engineered away in compounding. The same logic behind how to select plastic additives applies here, inverted in one respect: the performance criterion belongs to a machine outside the factory.

Do Tracers Change the Plastic? Processing, Properties and Appearance#

At the concentrations tracers need, the mechanical answer is no: lanthanide-doped oxide markers changed neither tensile, impact nor flexural properties of polypropylene or ABS up to 250 ppm, which is more than twice the recommended level. Those properties are measured to ISO 527-1/-2 for tensile, ASTM D256-26 and ISO 180 for Izod and ISO 179 for Charpy.

Thermal survival in the melt is not the binding constraint for the inorganic classes. Cerium(IV) oxide and yttrium(III) oxide are refractory and PTCDA melts above 500 °C, while an organic marker brings a lower ceiling: BBOT melts at 192 to 208 °C.

Two statements are established by the record.

• Mechanical neutrality to 250 ppm (0.025 wt%) in PP and ABS for lanthanide-doped oxide markers.
• Thermal headroom for the inorganic oxide and perylene candidates.

Two questions are not.

• Appearance. No colour difference to ASTM D2244-25, yellowness index to ASTM E313-20 or haze value to ASTM D1003-21 or ISO 14782 is recorded for any sorting marker.
• Long-term behaviour. No weathering, ageing or reprocessing data for a marked compound is recorded.

Colour neutrality should not be assumed from the mechanical result, because the record points the other way: a fluorescent species is visible at single-digit ppm in unpigmented polyolefin, which is the point of optical brighteners for plastics, where 5 to 10 ppm of BBOT shifts perceived whiteness. A marker at 100 ppm is 10 to 20 times that level.

How Is Tracer Performance Measured? Detection, Ejection and Purity#

Tracer performance is measured as 3 numbers on a real sorting line, detection rate, ejection rate and the purity of the output stream, and the published benchmark for all 3 comes from the digital watermark programme rather than from a tracer additive. The HolyGrail 2.0 programme run by AIM reports 99 % detection, 95 % ejection and 95 % purity from its phase 2 trials of digital watermarks, after phase 1 prototypes from Pellenc ST and Tomra exceeded 95 % ejection, and those are watermark results. The method index for testing plastic additives lists every standard named here.

There is no standard test method for tracer detectability in this reference. Detection, ejection and purity are project metrics, not standardised tests.

Laboratory detectability is a separate measurement from line performance, and only the first exists for tracer additives here: up-conversion markers were demonstrated at 980 nm excitation up to 10 W/cm² at 10, 100 and 1,000 ppm in HDPE film. No ISO, ASTM or EN method defines how tracer detectability is measured, so a specification names the excitation source, the detector and the acceptance threshold explicitly rather than citing a standard.

Are Tracers Allowed in Food-Contact Plastics?#

It depends on which element the marker contains: Regulation (EU) No 10/2011 caps europium, gadolinium, lanthanum and terbium at 0.05 mg/kg as a sum of all lanthanides, while yttrium, ytterbium, erbium and cerium have no entry at all in the sources checked. A europium-doped down-shifting phosphor therefore meets a numbered limit, while an ytterbium-sensitised up-conversion phosphor meets the general architecture of the Union list. The layer model is explained under plastic additive regulations.

General limits apply whatever the element: a generic specific migration limit of 60 mg/kg, an overall migration limit of 10 mg/dm², and credit for a functional barrier only where migration stays below 0.01 mg/kg. Nothing in this reference states that a marker is approved, banned or required for food contact; what follows is what the Union list contains and what it does not.

EU: the Annex II lanthanide limit of 0.05 mg/kg as a sum#

The EU limit that decides this family is unusual in 2 ways: it applies to europium, gadolinium, lanthanum and terbium together rather than separately, and it is expressed as the sum of all lanthanides at 0.05 mg/kg. Regulation (EU) 2020/1245 introduced that entry into Annex II of Regulation (EU) No 10/2011 with a remark requiring proof that the substance is present in the dissociated ionic form, verified here against the consolidated text of 14 July 2026.

The sum rule has a direct formulation consequence: two lanthanides in one compound share 0.05 mg/kg rather than each receiving it. Article 6(3)(a) allows salts of authorised acids, phenols and alcohols formed with the metals marked yes in Annex II, a list that includes all 4 lanthanides, so a marker built as such a salt inherits both the permission and the shared limit. How the Union list works is explained on EU 10/2011.

For scale, the neighbouring Annex II metal limits are aluminium 1, antimony 0.04, barium 1, cobalt 0.05, copper 5, iron 48, lithium 0.6, manganese 0.6, nickel 0.02 and zinc 5 mg/kg. At 0.05 mg/kg for 4 elements combined, the lanthanide entry is among the strictest in that table.

Yttrium, erbium, ytterbium and cerium have no entry in the sources checked, and an absence in a positive-list system is not a permission. Reading the Union-list architecture rather than quoting the regulation, a marker built on those elements needs a Union-list entry, a functional barrier or a placement outside the food-contact layer. All specific migration limits (SML) for additives are tabulated together.

Markers in a coating, an ink or a label instead of in the polymer#

Putting the marker on the label rather than in the wall changes the compliance question completely, because a label or a coating on the outside of a package is not in contact with the food. Larder and Hatton reviewed the 3 incorporation routes in 2022, extrusion into the polymer, coatings and labels, and PRISM chose luminescent coded labels rather than in-polymer markers. The security industry uses the same route, adding markers to printing ink, which vendors describe as common practice rather than something this reference records as a fact.

A label route reduces the food-contact question without removing it. Regulation (EU) No 10/2011 credits a barrier layer only where migration of the substance behind it stays below 0.01 mg/kg, and a layer holding migration below that value is a functional barrier. Set-off from the printed surface to the food-contact surface during reeling remains an assessment the converter owes.

Who Supplies Tracers? Technology Providers, Projects and the Gap in the Record#

No producer of a tracer additive grade is documented in this reference, which is itself the most useful thing this section can tell a formulator: the market is still organised around projects and sorting-technology companies rather than catalogue additives. No trade name, commercial grade, datasheet, market size or price for a tracer masterbatch exists in this record, and none is invented here. What exists is a short list of initiatives, equipment makers and research groups.

No additive producer, trade name or commercial tracer grade is recorded in this reference. The table lists the organisations the published record actually names.

Sourcing therefore runs through the sorting-technology route rather than an additive catalogue: the organisation that supplies the reader usually specifies the marker. Company profiles sit in the directory of plastic additive manufacturers and suppliers, where no tracer producer is listed, for the reason given above.

Complete List of Marker Substances Documented in This Reference (5)#

The complete list below gives the 5 marker substances this reference documents, with CAS numbers where they exist, the detection route and the food-contact position, and it is short for a reason: no producer of a dedicated tracer grade is in the public record.

The up-conversion and down-shifting phosphor compositions named on this page, for example Y2Ti2O7:Yb,Er and Y2O2S:Eu, are doped materials rather than single registered substances, and no CAS number for them is held in this reference.

Every substance named here has a record in the plastic additives database, where identity, dosage and regulatory files are kept in one form across all 43 additive families.

How Do Tracers Compare with the Other Ways to Identify a Plastic?#

A tracer is 1 of 4 ways to make a plastic object identifiable, alongside a digital watermark pressed into the surface, a laser mark burned into it and a chip attached to it, and only 2 of those 4 are additives. A digital watermark is a printed or embossed pattern and an RFID chip is a component, so neither is dosed into the compound. The 2 additives answer different readers: laser marking additives burn a mark a person can read, while a tracer leaves a code only a machine finds.

The near-infrared window used to excite an up-conversion marker at 980 nm is also used by IR absorbers and reheat additives, there to heat a PET preform rather than to read a code, and that shared band is why the 2 families are formulated with each other in mind.

Is a digital watermark (HolyGrail 2.0) an additive?#

No: a digital watermark is an imperceptible pattern printed on the label or embossed into the mould surface, so it adds no substance to the polymer at all, which is exactly why it is the main competitor to tracer additives rather than a member of the family. The HolyGrail 2.0 programme run by AIM reports 99 % detection, 95 % ejection and 95 % purity from phase 2 trials of digital watermarks, reached technology readiness level 9 in phase 3 with more than 130 participating companies, and concluded its research in March 2025, with HolyGrail 2030, Circular Packaging, launched in the same month as the successor programme.

The 2 approaches fail in different places. A watermark needs print or mould coverage, so a torn label or a removed sleeve takes the code with it, while a marker additive is distributed through the material, survives the loss of printing, and depending on the detection method can be read in black plastic. No cost comparison is recorded here.

Is a tracer the same as a laser-marking additive or an NIR-detectable black?#

No: a laser-marking additive helps a laser burn a human-readable mark into the surface at 1,064 nm, and an NIR-detectable black simply lets an existing sorter see a black object, while a tracer adds a code that only a machine looking for it can find. Laser marking works at 1,064 nm from an Nd:YAG or fibre laser, the dominant industrial wavelength, and produces a dark mark by carbonisation or a light mark by foaming, changing the polymer locally and permanently.

An NIR-detectable black solves the opposite problem: it replaces carbon black so the installed sorter can see the object, and adds no code. The 3 routes answer 3 readers, a person, an existing sorter and a dedicated detector, and the pigment-based ones sit inside the wider family of colorants for plastics.

Is a fluorescent leak-detection tracer dye the same product?#

No: the tracer dyes sold by the gallon for leak detection are added to a liquid so a technician can find where it escapes, and nothing about them relates to marking a solid plastic for sorting or authentication. They are fluid additives for pipes, cooling circuits and air-conditioning systems, and the shared word "tracer" is the only connection to this page. A tracer additive for plastics is compounded into a solid polymer at ppm level and read by a machine; a leak-detection tracer dye is dissolved in a working fluid and read by a person with an ultraviolet lamp.

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