A wash-off label adhesive is intended to help a label separate from a PET container during a defined recycling wash process. That description is useful, but incomplete. The recycling outcome depends on the whole labelled article: the PET bottle, label facestock, adhesive amount, inks, coatings, label coverage, wash process and downstream separation steps.
For a pressure-sensitive label on PET, the preferred outcome is generally that the label detaches cleanly, little or no adhesive remains on washed PET flakes, and the adhesive stays associated with the removed label rather than entering process water. The Association of Plastic Recyclers’ PET-EE-01 guidance identifies clean separation as desirable for relevant label formats, including pressure-sensitive paper and film labels. The applicable result, however, is a result for a defined construction under a defined evaluation process—not a universal statement that every PET package using that adhesive is recyclable.
What wash-off performance is meant to achieve
Pressure-sensitive labels must balance two conflicting requirements. In use, the adhesive needs enough bond strength to survive label application, handling, filling, distribution and consumer use. In recycling, that bond must release under the conditions used to process the container.
The desired release mechanism should not be confused with simple adhesive failure. A label that falls off during filling, refrigeration or wet handling has not delivered acceptable package performance. Conversely, a label that remains firmly attached through washing may carry adhesive, inks or label fragments into PET regrind and complicate downstream processing.
Recycling guidance commonly distinguishes between adhesive behaviours:
- Releasable adhesive: an adhesive that releases from at least one bonded surface under specified recycling conditions while remaining with its original substrate or substrates.
- Soluble or dispersible adhesive: an adhesive that enters the wash liquid to some degree under the process conditions.
- Non-releasing adhesive: an adhesive that remains attached to PET or leaves material on PET flakes after washing.
The terminology needs care because a material may behave differently in different recycling systems. FEICA notes in its adhesives and packaging recycling FAQ that releasable and soluble behaviour are distinct concepts and must be considered under the specific conditions of the recycling process.
For PET label applications, release with adhesive retention on the detached label is often preferable to dissolving adhesive into wash water. The RecyClass protocol for adhesives on PET bottle labels describes label detachment, minimal adhesive remaining on washed PET flakes and retention of the adhesive layer on the label as desired outcomes. It also notes that adhesive entering wash water can increase water-treatment demands. That does not make every soluble system unsuitable in every process, but it means water handling must be part of the technical assessment.
Why the adhesive cannot be specified in isolation
A purchase specification that says only “wash-off label adhesive” leaves out many variables that can change recycling behaviour. Adhesive chemistry matters, but it is only one layer of the construction.
The test article should be described as an assembled system, including:
| Construction element | Why it can affect recycling behaviour |
|---|---|
| PET article | Bottle colour, wall thickness, geometry, surface texture and mould-release contamination may affect application and release. |
| Label facestock | Paper and film labels differ in density, wet strength, fragmentation behaviour and separation route. |
| Adhesive grade | The exact grade, not a product family name, determines the supplier’s stated application and recycling scope. |
| Adhesive coat weight | A higher or lower adhesive mass can change bond formation, residue risk and the material entering the wash system. |
| Label size and coverage | Large labels alter the proportion of non-PET material and can affect sorting and separation. |
| Inks and decoration | Ink coverage, metallic effects, primers and pigments may change density, wash behaviour or flake contamination. |
| Overprint varnish or laminate | A protective layer can change label stiffness, water exposure and the way adhesive remains with the label. |
| Application conditions | Container temperature, condensation, line speed and pressure affect the original adhesive bond. |
The RecyClass evaluation protocol calls for identification of the label structure and density, adhesive technology, adhesive amount per surface area, and package description. This is a practical reminder for buyers: a favourable result for an unprinted film label with one adhesive coat weight should not automatically be transferred to a printed paper label, a metallised construction or a label with a different varnish.
The same discipline applies to performance in use. A construction intended for chilled beverages, condensation exposure, freezer storage, oil contact or refill use may need different bond performance from one used on a dry, ambient-temperature container. Changing adhesive grade simply to improve wash release can create failures at the filling line or in distribution.
Define the recycling process before requesting a wash-off claim
A supplier’s wash-off statement is interpretable only when it identifies the conditions under which release was evaluated. Ask which protocol, version and test configuration support the claim.
Relevant process variables can include:
- wash chemistry and concentration;
- wash temperature;
- residence time;
- agitation and mechanical action;
- bottle grinding or flake size before washing;
- ratio of labels to PET material in the test batch;
- float-sink or other downstream separation steps;
- rinsing and drying conditions; and
- the observations or measurements used to judge PET cleanliness and label separation.
Do not assign a universal wash temperature, caustic concentration or dwell time from a general product description. PET recyclers use different equipment, feedstocks and operating windows. Evaluation methods are designed to make test conditions repeatable for a stated purpose; they do not represent every commercial recycling plant.
The APR PET-EE-01 procedure is particularly relevant where its scope and current version match the intended market and package format. Its stated scope includes roll-fed, cut-and-stack and pressure-sensitive labels using paper or film substrates. The RecyClass protocol is another potentially relevant route where its geographic context, collection system and evaluation scope align with the intended application.
Before asking for a result, establish these three points:
- Which PET recycling stream is relevant? Identify the sales market, likely collection route and target recycler or recycling system.
- Which assessment method is being used? Request the full method name, version, date and scope rather than a shorthand such as “APR tested.”
- What exact construction was evaluated? Confirm every material layer and the PET article used for the test.
If a recycler has written acceptance requirements, treat those as additional operational requirements. A protocol result can support a technical assessment, but a recycler may have feedstock, sorting or process constraints that the protocol does not address.
Turn the requirement into a construction specification
A workable specification separates in-use requirements from recycling requirements, then documents the complete construction that must meet both.
For the label supplier, converter and adhesive supplier, request the following information.
Material and construction details
- Adhesive manufacturer, exact grade and adhesive technology.
- Adhesive coat weight or application amount, with unit and permitted tolerance.
- Facestock material, thickness or basis weight, density where relevant, and wet-strength treatment where applicable.
- Release liner construction if it affects converting or application, even though it is not part of the applied label.
- Ink system, ink coverage, primer, overprint varnish, laminate and any metallic or special-effect decoration.
- Label dimensions, placement, percentage of bottle coverage and orientation.
- PET container grade, colour, shape, surface condition and intended fill volume.
Application and use requirements
- Minimum and maximum application temperature.
- Container condition at labelling, including condensation, moisture or residual product risk.
- Line speed, dispense method and expected label application pressure.
- Required initial tack, final adhesion and repositionability, if relevant.
- Exposure to chilled distribution, ice-water contact, refrigeration, freezer conditions, oils, abrasion or refill cycles.
- Storage conditions and shelf-life limits for label stock and finished labels.
Recycling requirement
State the requirement in conditional, testable language. For example: “The production-representative labelled PET article shall be evaluated against the agreed protocol version and acceptance criteria for the intended market.” This is more useful than requiring a generic “recyclable adhesive.”
Also define what evidence is acceptable. A material datasheet may be enough for preliminary screening, but final package approval usually needs documentation for the assembled construction. Ask whether the report covers printed labels and whether the tested ink, coating and adhesive amount match the production bill of materials.
Verify the finished labelled package
Documentation review is a necessary first step, not final proof. The strongest verification route compares a production-representative package with the construction described in the test record.
A practical approval workflow is:
- Map the complete bill of materials. Include the bottle, closure where relevant to the assessment, label substrate, adhesive, inks, coatings and decoration.
- Screen supplier documentation. Check grade names, revision dates, application limits and the exact construction named in any recycling report.
- Compare the proposed article with the evaluated article. Identify changes in facestock, adhesive coat weight, label area, print coverage, varnish, bottle colour or geometry.
- Agree the relevant method and acceptance criteria. Involve the brand owner, label converter, adhesive supplier and, where possible, a recycler or recycling adviser familiar with the target market.
- Test representative samples where required. Samples should reflect commercial materials and processes rather than an unprinted laboratory substitute.
- Control changes after approval. Treat a new ink supplier, added laminate, revised adhesive application weight or larger label as a potential requalification trigger.
The phrase “production representative” matters. An unprinted label may be appropriate for an early adhesive screen, but it does not establish the behaviour of a commercial label carrying dense graphics, white ink, metallic decoration, varnish or film lamination. Likewise, approval of a small front label does not necessarily cover a large wraparound pressure-sensitive label.
Keep a controlled record containing the approved artwork version, material codes, adhesive grade, coating specifications, PET container identification, test method, report date and stated limitations. This gives procurement and quality teams a way to detect when a substitution changes the basis of the recycling assessment.
Keep recyclability claims separate from adhesive results
A wash-off result can be technically valuable without proving a broad consumer-facing recyclability claim. A claim about the finished package may also depend on collection availability, sorting, regional processing infrastructure, market rules and the precise wording used on-pack.
The How2Recycle Guidelines for Use caution against generic recyclable claims or symbols where a package needs qualification. The appropriate claim, if any, must be reviewed for the market where it appears and should reflect the complete package rather than one component.
Avoid statements such as:
- “The bottle is recyclable everywhere because it uses wash-off adhesive.”
- “Wash-off means no adhesive enters the recycling process.”
- “APR-recognized” or “RecyClass-approved” unless documentation applies to the exact grade, construction and claim wording.
- “Suitable for food contact” based solely on an adhesive’s recycling behaviour.
Instead, describe the documented scope. For example: “The specified label construction has been evaluated under the named method and conditions,” provided the report actually supports that statement. Confirm legal, food-contact and environmental claims separately with the relevant documentation and authorities.
Questions to ask before approving a wash-off label adhesive
Use these questions in supplier reviews and package-change meetings:
- What is the exact adhesive grade and adhesive coat weight on the proposed label?
- Which label facestock, inks, varnishes and laminates were included in the supporting evaluation?
- Which PET bottle colour, geometry and label coverage were tested?
- What test method and version were used, and what wash and downstream conditions did it specify?
- Did the label detach from PET, and was adhesive residue on washed PET assessed?
- Was adhesive retention on the detached label or adhesive entry into wash water evaluated?
- Does the evidence cover the printed production label or only an unprinted sample?
- What changes require renewed review or testing?
- What collection, sorting and recycling route is expected in the target market?
- What qualified claim language, if any, is permitted for that market?
A wash-off label adhesive should be selected as part of a controlled PET package system. Specify the named construction, required in-use performance, relevant recycling conditions and evidence standard first; then use testing and change control to determine whether the finished package remains within that documented scope.
