RoHS Testing for Label Materials: Restricted Substances, Testing Methods, and Compliance Guide

RoHS testing for label materials verifies that facestock films, adhesives, inks, and release liners used on electrical and electronic equipment comply with the restricted substance limits of EU Directive 2011/65/EU and its amendment (EU) 2015/863. Because labels are multi-layer laminates, each homogeneous material layer must be individually tested for the ten regulated substances, including lead, cadmium, mercury, hexavalent chromium, PBB, PBDE, and four phthalates. This article explains the applicable standards, sample requirements, testing items, analytical methods, and common compliance questions for label material RoHS testing.

Technical Overview

RoHS (Restriction of Hazardous Substances) is a European Union directive, 2011/65/EU, that restricts the use of ten hazardous substances in electrical and electronic equipment (EEE). The original six substances were lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls (PBB), and polybrominated diphenyl ethers (PBDE). Amendment (EU) 2015/863 added four phthalate plasticizers: DEHP, BBP, DBP, and DIBP, bringing the total restricted list to ten substances commonly known as RoHS 10.

Although a label is not itself an electrical product, labels, nameplates, rating plates, and printed films attached to or incorporated within EEE are treated as component parts and must therefore satisfy RoHS requirements. A pressure-sensitive label is a composite structure consisting of a facestock layer, an adhesive layer, and often a release liner, printing inks, varnishes, or protective laminating films. Under the RoHS definition, each layer that cannot be mechanically disjointed into different materials is a "homogeneous material" and must independently meet the concentration limits. This makes label materials a real compliance risk area: PVC films may contain phthalate plasticizers, pigments may contain cadmium or lead, and some adhesive formulations or inks may introduce regulated flame retardants or heavy metals.

The reference testing methodology is the IEC 62321 series, which is harmonized with European standards (EN IEC 62321) and mirrored in Chinese national standards such as GB/T 26125 and the GB/T 39560 series used for China RoHS (GB/T 26572) conformity assessment. Technical documentation supporting RoHS declarations can be structured according to EN IEC 63000. Manufacturers and converters typically engage accredited third-party laboratories operating under ISO/IEC 17025 to generate the analytical reports required by EEE brand owners and supply chain auditors.

Testing Samples

Paper Facestock Materials

Coated art paper, thermal paper, kraft paper, and vellum facestocks are separated from the adhesive and liner, shredded or milled, and tested as distinct homogeneous materials. Thermal coatings deserve particular attention because imaging layers may contain metal-based developers or pigments.

Plastic Film Facestock Materials

Polyethylene terephthalate (PET), polypropylene (PP/BOPP), polyethylene (PE), polyvinyl chloride (PVC), and synthetic paper films are the highest-risk layers in a label construction. Flexible PVC frequently contains phthalate plasticizers, and some film grades may include lead- or cadmium-based heat stabilizers or colorants, so full wet-chemical confirmation is recommended rather than screening alone.

Adhesive Layers

Acrylic emulsion adhesives, solvent acrylic adhesives, rubber-based adhesives, hot-melt adhesives, and removable adhesives are separated from the facestock by cryogenic or solvent-assisted delamination. The adhesive is a separate homogeneous material and must be tested on its own, since plasticizers, tackifiers, or stabilizers in the formulation can introduce restricted substances.

Release Liners and Silicone Coatings

Glassine, PET, or PE release liners with silicone release coatings are tested as liner substrate and coating, either separately or as a combined construction depending on the disassembly capability declared by the laboratory.

Inks, Varnishes, and Decorative Layers

Printing inks, overprint varnishes, metallic hot-stamping foils, and protective over-laminates are dissected from printed labels and analyzed individually. Pigment concentrates are a known potential source of cadmium, lead, and hexavalent chromium in certain color formulations.

Finished Labels and Nameplates

Complete die-cut labels, rating plates, barcode labels, and membrane switch overlays can be submitted for full constructions testing, in which the laboratory performs layer-by-layer disassembly and reports results for every homogeneous material identified.

Testing Items

RoHS testing for label materials covers the ten restricted substances with the following maximum concentration values (MCV) in any homogeneous material:

• Lead (Pb) - limit 0.1% (1000 ppm)
• Cadmium (Cd) - limit 0.01% (100 ppm)
• Mercury (Hg) - limit 0.1% (1000 ppm)
• Hexavalent chromium (Cr(VI)) - limit 0.1% (1000 ppm)
• Polybrominated biphenyls (PBB) - limit 0.1% (1000 ppm)
• Polybrominated diphenyl ethers (PBDE) - limit 0.1% (1000 ppm)
• Bis(2-ethylhexyl) phthalate (DEHP) - limit 0.1% (1000 ppm)
• Butyl benzyl phthalate (BBP) - limit 0.1% (1000 ppm)
• Dibutyl phthalate (DBP) - limit 0.1% (1000 ppm)
• Diisobutyl phthalate (DIBP) - limit 0.1% (1000 ppm)

For clients supplying only the Chinese market, six-substance testing in line with GB/T 26572 may be sufficient, while exports to the European Union require the full ten-substance scope. Many buyers also request screening of related substances such as halogens or short-chain chlorinated paraffins as an additional commercial requirement beyond the legal RoHS scope.

Testing Methods

The IEC 62321 standard series defines the accepted analytical procedures. A typical testing workflow consists of an initial non-destructive screening step followed by wet-chemical confirmation of any flagged elements:

• X-ray fluorescence spectrometry (XRF) per IEC 62321-3-1 for rapid screening of lead, cadmium, mercury, chromium, and bromine in films, papers, and coatings
• Acid digestion (microwave or hot-block) followed by ICP-OES, ICP-MS, or AAS per IEC 62321-5 for quantitative determination of lead and cadmium
• Cold vapor atomic absorption spectrometry (CV-AAS) or ICP-MS per IEC 62321-4 for mercury determination
• Colorimetric determination of hexavalent chromium using the diphenylcarbazide method or boiling-water extraction per IEC 62321-7-1 and IEC 62321-7-2 for polymer and coated surfaces
• Gas chromatography-mass spectrometry (GC-MS) per IEC 62321-6 for PBB and PBDE flame retardants after solvent extraction
• GC-MS analysis per IEC 62321-8 for the four phthalates (DEHP, BBP, DBP, DIBP) after solvent extraction of the polymer or adhesive matrix

Sample preparation follows IEC 62321-2, which requires mechanical disassembly into homogeneous materials before milling or cutting. A practical sample requirement is approximately 5 to 20 grams of each homogeneous material, or several A4 sheets of a finished label construction, along with a material safety data sheet or formulation declaration when available. Standard turnaround time at accredited third-party laboratories is typically five to seven working days, with expedited services available. The final report presents detected concentrations against the RoHS limits and issues a pass or fail conclusion for each layer tested.

Applications

RoHS test reports for label materials are used across a wide range of industries and compliance scenarios:

• Rating plates, serial number labels, and barcode labels applied to consumer electronics, IT equipment, and telecommunication devices covered by the EU RoHS scope
• Nameplates and instruction labels for household appliances, lighting equipment, power tools, and cables
• Labels and overlays for medical devices, monitoring and control instruments, and automatic dispensers that fall within EEE categories
• Battery labels and component identification labels requiring both RoHS and REACH documentation in battery supply chains
• Supplier declarations and material declarations requested by OEM brand owners during sourcing audits and incoming material inspections
• Technical documentation files supporting CE marking conformity per EN IEC 63000 and market surveillance responses
• China RoHS disclosure tables and eco-design documentation prepared according to GB/T 26572 requirements

FAQ

Do label materials really need RoHS testing if the label itself is not electrical? Yes. RoHS applies to all homogeneous materials in electrical and electronic equipment, and any label, film, tape, or printed overlay attached to an EEE product becomes part of that product. Brand owners therefore require RoHS declarations from label converters just as they do for plastics, metals, and electronic components.

Why must each layer be tested separately? RoHS limits apply to homogeneous materials, not to the finished article. A pressure-sensitive label contains at least three layers (facestock, adhesive, liner), and each must individually comply. Testing only the finished laminate as a whole can mask an over-limit adhesive or ink layer.

Is XRF screening sufficient for compliance? XRF screening is a fast first step, but it cannot distinguish hexavalent chromium from total chromium, cannot speciate brominated flame retardants, and cannot detect phthalates at all. Any screening result that is inconclusive or above screening limits must be followed by wet-chemical confirmation testing.

Which layers of a label most commonly fail? Flexible PVC facestocks are the leading source of phthalate failures, followed by pigmented inks containing cadmium or lead, adhesive plasticizers, and legacy flame-retarded films containing PBDE.

How long is a RoHS test report valid? There is no official expiration date, but reports are conventionally accepted for about one year because formulations and raw material suppliers can change. Most buyers request annual retesting or updated declarations, and a new report is required whenever the material formulation changes.

What is the difference between RoHS 6 and RoHS 10? RoHS 6 refers to the original six substances, while RoHS 10 includes the four phthalates added by (EU) 2015/863, which have been mandatory for EU market placement since July 2019. Current EU-bound label materials must be tested against all ten substances.