German LFGB Silicone Seals for Drinkware: A Test Plan

LFGB silicone seals are not approved by a single German certificate or one universal migration test. For a reusable bottle, tumbler, travel mug or thermal carafe, the correct approach is to define the seal’s real food-contact conditions, review its formulation and processing, test the finished silicone component against the applicable requirements, and keep evidence that connects the tested part to production lots.

This distinction matters because the small gasket inside a lid can influence leakage, taste, odour and food-contact compliance. A supplier statement saying “food-grade silicone” may be useful background, but it does not by itself show that the exact gasket in the finished drinkware is suitable for hot coffee, cold water, repeated cleaning or another intended use. Golmate’s earlier overview of food-grade silicone in drinkware gaskets explains the material basics. This guide focuses on the German-market test plan and evidence package.

Start with the Correct Legal Map

The term “LFGB test” is common in sourcing conversations, but it compresses several layers into one label. At EU level, Regulation (EC) No 1935/2004 sets the general safety principle for food-contact materials: under normal or foreseeable conditions of use, a material must not transfer constituents to food in quantities that may endanger health, unacceptably change food composition or impair organoleptic properties.

Manufacturing is also subject to Regulation (EC) No 2023/2006 on good manufacturing practice. It requires an effective quality-assurance system, controlled starting-material specifications, documented procedures, quality control and records relevant to compliance. For a gasket, this makes the compound specification, curing route, post-curing parameters and lot traceability part of the compliance story rather than separate factory paperwork.

Germany’s LFGB Section 31 links national market controls to the Article 3 requirements. For silicone, which does not have a fully harmonised EU material-specific measure comparable to the plastics regulation, the German Federal Institute for Risk Assessment publishes material recommendations. The BfR food-contact recommendations database explains an important nuance: the recommendations are not binding legal standards, but they represent the current state of science and technology for assessing materials such as silicone.

For drinkware seals, the central technical reference is BfR Recommendation XV on Silicones. Buyers should therefore avoid describing a generic supplier certificate as “government approval.” A more defensible statement identifies the exact article, intended use, report, formulation reference, test conditions and conclusions.

Define Intended Use Before Requesting Tests

A laboratory cannot design a meaningful programme from “silicone gasket for bottle” alone. The brand owner and drinkware factory should first agree a use specification. At minimum, document:

• Product type: bottle, straw tumbler, travel mug, food jar, airpot or thermal carafe.
• Contact mode: direct immersion, intermittent wetting, splash contact, vapour exposure or contact only when the product is inverted.
• Food types: water, acidic drinks, coffee, tea, dairy beverages, oily formulations or other intended contents.
• Temperature: cold fill, room-temperature use, hot fill, contact with boiling water during preparation, or another realistic maximum.
• Time and repetition: typical use duration, storage duration, repeat-use expectation and cleaning cycle.
• Cleaning: hand washing, dishwasher claim, sanitising procedure and any recommended restrictions.
• Consumer group: general adult use, children, or another scenario that may change the risk assessment.

The test severity should be justified by these conditions rather than selected only because a more severe protocol sounds safer. An unjustified condition can deform a gasket or create results that do not represent the intended article. Conversely, a mild protocol can miss foreseeable hot-contact or repeated-use exposure. The laboratory should select simulants, time, temperature and repetition based on the declared use and current applicable guidance.

The gasket must also be assessed as part of a lid system. Compression, groove geometry, venting and closure torque can determine whether the seal stays in position and whether liquid reaches surfaces that were assumed to be non-contact. This is why compliance review should be coordinated with functional sampling, not handled as an isolated material purchase. A structured water bottle sample evaluation can connect material evidence with fit, leakage, opening force and cleaning access.

Lock the Silicone Compound and Process

Silicone is a family of formulations, not one invariant substance. Two visually identical rings may use different polymers, fillers, pigments, catalysts, cross-linking systems or processing aids. Even when both are described as platinum-cured, their formulation histories, volatile profiles and post-curing conditions may differ.

Before testing, the evidence package should identify the compound sufficiently to prevent silent substitution. A practical specification normally records the compound code, manufacturer, colour or pigment reference, hardness range, cure system, permitted processing aids, manufacturing location and revision date. Confidential formulation details may remain between the compound supplier and laboratory, but the finished-goods supplier still needs a controlled reference that connects the report to the purchased part.

Post-curing deserves particular attention. It may reduce residual volatile or extractable components, but the required time and temperature depend on the compound, cross-linking system, gasket geometry and supplier process. “Post-cured” should therefore be an auditable process parameter, not a general marketing phrase. If production uses a different oven load, dwell time or part thickness from the tested sample, the relevance of the report may need review.

Build the Laboratory Test Programme

A qualified laboratory should confirm the final scope. The following elements provide a useful briefing structure for a German-market reusable drinkware gasket.

1. Composition and restriction review

Compare the declared raw materials and processing aids with the relevant sections of BfR Recommendation XV. The recommendation lists permitted starting materials and production aids for silicone elastomers and includes restrictions for certain substances or conversion products. Where Recommendation XV refers to specific restrictions under Regulation (EU) No 10/2011, those cross-references should be captured in the review rather than assuming the plastics regulation directly covers the complete silicone article. Golmate’s guide to EU 10/2011 for drinkware lids provides the separate framework for PP, Tritan and other plastic lid components.

2. Volatile and extractable components

BfR Recommendation XV states that silicone elastomers should release no more than 0.5% volatile organic components and no more than 0.5% extractable components. The same recommendation links to the BfR’s method for determining volatile compounds in silicone consumer products. The report should state the method, specimen preparation, conditioning and result rather than showing only “pass.”

3. Peroxide and relevant reaction products

Recommendation XV says finished silicone elastomers must not test positively for peroxides. Additional substance-specific checks may be relevant to the cross-linking system. The correct analyte list depends on the compound declaration, so a brand should not copy a competitor’s report scope without confirming that the same chemistry applies.

4. Migration and sensory suitability

The general framework covers health, unacceptable compositional change and organoleptic deterioration. A test plan may therefore include migration work and sensory checks appropriate to the intended contact. Odour or taste is especially commercially important for closures because the gasket sits close to the drinking interface. Passing a chemical screen does not automatically prove that a user will not notice an off-odour, and a sensory result cannot replace chemical assessment.

5. Colour and other formulation-specific risks

Pigments, fillers and other intentionally added components should match the tested formulation. A natural translucent seal and a black or brightly coloured gasket should not automatically share one report. A technical assessment may support a family approach, but the grouping rationale, worst-case selection and applicable restrictions should be documented.

Test the Finished Gasket, Not Only Raw Material

A raw-material statement is valuable for supplier qualification, yet it cannot capture every effect of moulding, curing, post-curing, storage and contamination. The finished gasket is the article that reaches the lid assembly and should normally be represented in the compliance evaluation.

Sample selection should cover production-relevant thickness and geometry. If several gasket sizes use the same controlled compound and process, the laboratory may be able to define a representative worst case. That decision should be technically justified. Surface-area-to-volume ratio, part thickness, colour and processing conditions may influence the choice.

The complete lid should also receive functional tests. Typical checks include:

• gasket seating and resistance to rolling or pinching during assembly;
• leakage after repeated opening, closing and cleaning;
• compression set or loss of recovery under expected use;
• fit after hot and cold exposure;
• retention of removable seals during normal use;
• cleanability, drainage and the absence of inaccessible residue traps;
• taste and odour observations with the intended beverage range.

These are product-validation items, not substitutes for legal compliance testing. Together, however, they reduce the risk of a report that looks complete while the production closure still leaks, traps residue or exposes an unassessed material.

Create an Evidence Package Buyers Can Audit

A useful compliance file is organised around traceability and decisions. It should allow a reviewer to answer four questions: What exactly was tested? For which use? Does production match it? What happens when something changes?

Under Regulation (EC) No 1935/2004, traceability should operate through all stages. A brand’s file should therefore connect the gasket compound lot to the moulded part lot, lid assembly and finished-drinkware batch. For a German retailer or importer, a short compliance summary can sit above the technical records, but it should not replace them.

Control Changes After Approval

Most compliance gaps do not begin with the first sample; they arise when a component changes after approval. A new pigment, second-source compound, revised hardness, different catalyst, relocated moulding line or shortened post-cure may affect the basis of the report. Tooling changes can also alter gasket thickness, compression and contact area.

Set a written rule that these changes require review before use. The review may conclude that existing evidence remains applicable, that a limited verification is sufficient, or that full retesting is needed. The decision should be recorded by competent technical personnel rather than left to an informal email.

Incoming inspection then confirms routine consistency. Useful checks typically include supplier and part number, colour, dimensions, hardness where appropriate, visual defects, odour, contamination, lot identification and a certificate tied to the shipment. Final inspection should connect to the broader drinkware pre-shipment checklist, including closure assembly and leak performance.

Common Claims That Need Correction

“The silicone is FDA and LFGB certified”

This wording is often too broad. Ask which regulation or recommendation was assessed, which laboratory issued the report, which compound and article were tested, and which use conditions the conclusion covers. Regulators do not generally issue a universal brand certificate for every future gasket made from a named material.

“Platinum-cured means automatically compliant”

Platinum-cured silicone can be a suitable technical choice, but cure chemistry alone does not establish compliance. Formulation, catalyst limits, processing, post-curing, finished-article testing and intended use still matter.

“One natural-colour report covers every colour”

It may not. Pigments and additives can change the assessment. A justified worst-case family may be possible, but the rationale needs documentation.

“A component pass guarantees the whole lid”

No. A lid may combine silicone, PP, Tritan, pigments, adhesives or other materials. Each food-contact component needs an appropriate basis, and the assembled closure needs functional and foreseeable-use validation. Broader product-safety duties, including traceability and corrective-action planning, should also be aligned with the EU GPSR drinkware workflow.

Procurement Questions for a Drinkware Factory

Before approving a lid with silicone seals for Germany, ask the manufacturer to answer these questions with document references:

1. What is the exact gasket part number, drawing revision and compound code?
2. Is the seal in direct, intermittent or foreseeable food contact in every lid position?
3. What beverages, temperatures, durations and cleaning methods define the intended use?
4. Which BfR Recommendation XV sections and other restrictions were reviewed?
5. Was the tested specimen a finished gasket made with the production cure and post-cure?
6. Do the report and supplier declaration identify the same formulation and colour?
7. How are compound, moulding, colour and supplier changes approved?
8. How does the factory trace a gasket lot into the final drinkware batch?
9. Which incoming and assembly checks control dimensions, odour, seating and leakage?
10. Who reviews the evidence when the target market or intended beverage changes?

The answers should be proportionate to the product risk and commercial programme. A standard water-bottle seal and a high-temperature thermal-carafe valve may require different conditions and controls. The intended use, complete construction and current regulatory interpretation determine the final scope.

A Practical Approval Sequence

For most new developments, the sequence is straightforward: define use, freeze the bill of materials, review the compound, agree the laboratory plan, test production-representative gaskets, validate the assembled closure, approve a controlled golden sample, and connect routine lots to the evidence file. Retesting is then driven by planned review intervals, market requirements and material or process changes rather than by calendar alone.

Golmate develops stainless-steel drinkware and PP-based closure systems around target-market and use-scenario requirements. For a German programme, share the beverage, temperature, cleaning claim, closure concept and retailer documentation needs at the specification stage. We can then coordinate gasket geometry, compound traceability, test-sample preparation and production controls with the appropriate independent laboratory. Final compliance conclusions should always remain tied to the exact product and intended use.