How to Choose an Aluminum Tin Lining Without Failing a Compatibility Test

The compatibility hold, written out, because it is the one test that settles arguments that documents cannot:

Acceleration factor = 2 ^ (ΔT ÷ 10)
Ambient shelf life covered = Hold duration × Acceleration factor

Holding filled tins at 55 °C against a 25 °C ambient gives ΔT = 30, so the factor is 2³ = 8:
4 weeks × 8 = 32 weeks, roughly eight months of ambient shelf life
6 weeks × 8 = 48 weeks, roughly eleven months

That is an approximation from chemical kinetics, not a guarantee, and it is discussed honestly in the methodology section at the end. It is still the cheapest thing you can do that turns a lining decision from an opinion into evidence.

Lining Decision Reference Chart

Before the detail, the chart. Read down the left for what is in your tin, and across for what that implies. Nothing here depends on which of our bodies you choose.

What is in the tin	Bare aluminum acceptable?	Typical lining decision	The document you will be asked for
Anhydrous solid balm, wax, poured candle	Usually yes	Often unlined; confirm with a hold test	None for a candle; cosmetic safety report entry for a balm
Dry tea, dry powder, dry solids	Usually yes	Often unlined, or lined for aroma retention rather than corrosion	Food-contact declaration for the contact surface
Emulsion or anything containing free water	No	Lined; specify the lacquer chemistry	Food-contact or cosmetic declaration, plus migration data
pH below 5 or above 9	No	Lined; chemistry chosen for the pH	As above, with the simulant and condition stated
Essential oils, fragrance at concentration	No	Lined; solvent resistance is the deciding property	As above, plus a solvent-resistance result
Salt-containing food	No	Lined; chlorides attack the oxide film	21 CFR 175.300 compliance for the US; Article 3 evidence for the EU

The right-hand column is the one buyers underestimate. In every row where a lining is required, a document is required with it — and the document is specific to the market and to the contact surface, not to the tin.

Why the Compliance Document You Were Sent Is for the Wrong Material

Ask a supplier for EU food-contact compliance on a lined tin and there is a good chance you will receive a Declaration of Compliance citing Regulation (EU) No 10/2011. It is a real regulation, correctly named, properly formatted — and it does not govern your lining.

Regulation 10/2011 is the specific measure for plastic materials and articles in contact with food. Its Article 2(3) says, in full: “This Regulation shall be without prejudice to the EU or national provisions applicable to printing inks, adhesives or coatings.” A lacquer applied to a metal substrate is a coating. It is outside the regulation.

There is a genuine subtlety worth knowing so you do not over-correct. Article 2(1)(c) brings plastic articles that are printed or covered by a coating into scope — but that is the plastic being regulated, with a coating on it. An aluminum body is not a plastic article, so neither it nor its lacquer is covered.

What governs the lining instead is the framework regulation, Regulation (EC) No 1935/2004, whose Article 3(1) requires that materials be manufactured under good manufacturing practice so that under normal or foreseeable use they “do not transfer their constituents to food in quantities which could: (a) endanger human health; or (b) bring about an unacceptable change in the composition of the food; or (c) bring about a deterioration in the organoleptic characteristics thereof.” Plus two substance-specific EU acts that do reach coatings directly, covered in the next two sections.

2-Document Compliance Gate

Gate	What to require for the EU	What to require for the US	Received?
1. The instrument	Declaration referencing Regulation (EC) No 1935/2004 Article 3, plus Regulation (EU) 2024/3190 (BPA) and Regulation (EC) No 1895/2005 (epoxy derivatives) status	Statement of compliance with 21 CFR 175.300, naming the food types and conditions of use covered	______
2. The evidence behind it	Migration testing with the simulant, time and temperature stated — not a bare assertion	Extraction results against the limits in 175.300(c), with the test protocol from 175.300(d)	______

One more document to be sceptical of. If a supplier cites a BfR Recommendation for your can lacquer, check which one. BfR Recommendation XIV is Polymer Dispersions. Reviewing the BfR list, there is no BfR Recommendation covering internal organic lacquers for metal food cans at all; the nearest, Recommendation LI, is for temperature-resistant coatings on frying, cooking and baking utensils. A BfR citation here is not evidence, and a compliance reviewer will notice.

Before your next lined order, ask which specific instrument the declaration is written against — if the answer is 10/2011 and the substrate is metal, the document needs replacing rather than filing.

Why Your Lacquer Can Be Legal in the US and Prohibited in the EU

The two jurisdictions have diverged sharply on one substance, and the divergence now sits inside the transition period of a live regulation.

The EU. Commission Regulation (EU) 2024/3190, in force from 20 January 2025, prohibits the use of BPA and its salts in the manufacture of the listed food-contact materials and the placing on the Union market of articles made with it. The list in Article 1(2) runs: adhesives, rubbers, ion-exchange resins, plastics, printing inks, silicones, and — item (g) — varnishes and coatings. It repeals Regulation (EU) 2018/213, so the old 0.05 mg/kg specific migration limit for BPA in varnishes and coatings is no longer the rule; a prohibition is.

The US. FDA continues to authorise BPA-based epoxy resins as can linings and states that available information continues to support the safety of BPA for the currently approved uses in food containers and packaging. The only US restrictions are two abandonment-based amendments from 2012 and 2013 covering polycarbonate baby bottles and infant-formula packaging — not safety findings, and not applicable to a balm or tea tin.

So the same lacquer can be entirely lawful on a US shelf and unlawful on an EU one. For a brand launching into both markets from one production run — which is now the normal pattern rather than the exception — that means the EU rule sets the specification for both.

2-Market Lining Legality Gate

Question	EU answer	US answer	Your SKU
Is BPA permitted in the lining?	No — prohibited by Regulation (EU) 2024/3190	Yes, for the currently approved uses	______
Are BADGE and its hydrolysis products restricted?	Yes — Regulation (EC) No 1895/2005: BADGE plus BADGE.H₂O plus BADGE.2H₂O limited to 9 mg/kg, BADGE chlorohydrins to 1 mg/kg, BFDGE and NOGE prohibited	Governed through the 21 CFR 175.300 component lists and extraction limits rather than by a dedicated rule	______
Which rule sets the specification for a dual-market run?	The stricter of the two, which for BPA is the EU — specify once, to the EU rule		______

Worth noting what is not harmonised: there is no EU specific measure for coatings as a material class. The Commission’s own position is that in the absence of specific EU measures, Member States may maintain or adopt national provisions under Article 6 of 1935/2004. The Council of Europe’s Resolution ResAP(2004)1 on coatings and its Policy Statement, current version 3 dated 12 February 2009, are the nearest thing to a European technical reference — and they are recommendations, not law.

If you sell into both markets, write the EU requirement into the specification even for US-bound stock — running one lacquer is cheaper than segregating two.

Why an Unlined Tin Passes on the Bench and Fails at Month Nine

Corrosion and migration are both slow. A sample filled last week and inspected today has been given no opportunity to fail. The failure mode is not that the lining was wrong on day one; it is that nobody looked at day 270.

The standard tool for this is a timed hold at elevated temperature, and it is within the reach of any brand with an oven and a set of scales.

4-Week Accelerated Compatibility Hold

Step	What to do	What it catches	Result
1	Fill 20 tins with the real finished formulation, not a placebo	Fragrance and preservative systems are frequently the aggressive component; a placebo hides them	______
2	Cap at the production torque; hold 10 upright and 10 inverted	Inverted units put the product against the lid and the liner, which is where most compatibility failures start	______
3	Hold 4 weeks at 55 °C, with a control set at ambient	Compresses roughly eight months of ambient life at Q10 = 2	______
4	Inspect at weeks 1, 2 and 4: interior surface, product colour, odour, weight loss	Weight loss detects loss through the seal; odour detects organoleptic change, which is one of the three Article 3 tests	______
5	Cross-cut adhesion on the lacquer at week 4 per ASTM D3359-23 Method B or ISO 2409:2020	A lining that has softened or lost adhesion during the hold will fail here before it fails in market	______

Two design details in that table matter more than the temperature. Inverting half the samples is what tests the lid liner, and the lid liner is a different material from the body lining. Recording weight is what turns “it looks fine” into a number; a consistent weight loss across the inverted set is a seal problem, not a lining problem, and you want to know which one you have.

Run the 4-Week Accelerated Compatibility Hold before you commit to tooling, not after the first production run — the cost is twenty tins and an oven, and it is the only step here that produces evidence rather than paperwork.

Why “Food Grade” Is Not a Specification

“Food grade” is an adjective. The US regulation that actually applies to a lined metal tin is a structured one, and it is worth understanding because it tells you exactly which questions to ask.

21 CFR 175.300, Resinous and polymeric coatings, opens by permitting such coatings to be safely used as the food-contact surface of articles “in accordance with the following prescribed conditions”. Paragraph (a) requires that the coating be “applied as a continuous film or enamel over a metal substrate”, or applied to any suitable substrate as a continuous film that serves as a functional barrier. Compliance then depends on two things together: every component being authorised under the lists in paragraph (b), and the finished coating passing the extraction limits in paragraph (c) using the protocol in (d).

The protocol is not one test. It is a grid: food types and conditions of use. The taxonomy the FDA regulations cross-reference runs food types I through IX — from non-acid aqueous (I) through low-moisture fats and oils (V) to dry solids with free fat on the surface (IX) — and conditions of use A through H plus J, from high-temperature heat sterilisation (A) through room-temperature fill and storage (E) to frozen storage (G).

5-Question Lacquer Declaration Audit

Question to put to the supplier	Why it matters	Answer on file
1. Which food type is the declaration written for?	A declaration for type VIII dry solids does not cover a type V balm	______
2. Which condition of use?	Condition E (room temperature fill and store) is the usual one for tins; a declaration written for condition A is answering a different question	______
3. Is the coating continuous over the metal, per 175.300(a)?	This is a stated requirement, not a quality preference	______
4. What extraction results support it?	The limits in 175.300(c) are numeric; a declaration with no numbers behind it cannot be audited	______
5. Does it cover the lid liner as well as the body?	They are different materials from different suppliers and are routinely covered by different documents — or by only one	______

Question 5 is the one that catches almost everybody. For an inverted tin in a warm warehouse, the lid liner is a food-contact surface with as much exposure as the body, and it is frequently outside the scope of the declaration on file.

Match the food type and condition of use in the declaration against your actual product and storage before you accept it — a mismatched declaration is worse than none, because it looks like compliance.

Why the Coating You Asked For Is Not Always the Coating You Got

A lining is not one thing. It is a build: what goes on first, what goes on top, how many passes, cured at what temperature. Buyers specify a name — “epoxy”, “gold lacquer”, “food-grade lining” — and the factory specifies a build. When the build changes between runs, the name on the purchase order does not.

3-Layer Coating Build Register

Field	What to record	What changes if it drifts	Your build
Chemistry	The resin family and, where relevant, the supplier’s product code	Chemical resistance, cure schedule, and which compliance documents apply	______
Film weight	Applied film weight in g/m², or dry film thickness in µm, with a tolerance	Barrier performance and flexibility; too thin means porosity, too thick means cracking on the draw	______
Cure	Peak metal temperature and time at temperature	Under-cure leaves extractables and soft film; over-cure embrittles it	______

Film weight is the field to insist on, because it is measurable at incoming inspection and because it is the one most often traded away quietly under cost pressure. A tolerance band on film weight converts “lined” from a yes/no into something an inspector can check.

Put film weight and cure schedule on the drawing alongside the resin family — a lining specified only by name is a specification that cannot be violated, and therefore cannot be enforced.

Why a Coating That Passes Adhesion Can Still Have Holes In It

Adhesion and continuity are different properties and they need different tests. A lacquer can be perfectly adherent across the whole surface and still have pinholes through to the metal, particularly at the base radius and in the thread where the draw stretched the film hardest.

3-Test Coating Integrity Matrix

Test	Answers	Correct citation	Result
Cross-cut adhesion	Does the film stay attached to the metal?	ASTM D3359-23 Method B for films under 125 µm, or ISO 2409:2020 — note ISO 2409 is not suitable above 250 µm or for textured coatings	______
Solvent rub	Is the film fully cured?	ASTM D5402-19(2024) — but see the caveat below	______
Continuity / metal exposure	Are there holes through to the metal?	See the note below — this is the one with no standard behind it	______

The caveat on solvent rub. ASTM D5402 deliberately does not specify the solvent, the number of double rubs, or the expected result. So “passes MEK double rub per ASTM D5402” is not a specification — it names a procedure with all its variables left blank. State the solvent and the rub count, or the line means nothing.

The note on continuity. The instrument the can industry uses for this is the enamel rater, which applies a fixed low DC voltage across an electrolyte in the can and reads leakage current in milliamps as a proxy for exposed metal. It is genuinely useful and it is not a standardised method: there is no ASTM, ISO or DIN designation for it, and the acceptance limits are set in supply contracts by fillers and can makers rather than by any published standard. Do not write “per ASTM” next to an enamel rater result. If you want a standardised discontinuity method, the closest is ASTM D5162-24 for holiday testing of non-conductive coatings on metallic substrates — although its thickness framing is aimed at tank and pipe linings far above a 5–12 µm can lacquer, which is precisely why the industry uses the enamel rater instead. And do not reach for ISO 2746 because it has the word enamel in it; that standard is for vitreous and porcelain enamel, not organic lacquer.

Ask for a continuity figure in milliamps with the acceptance limit stated in the contract, and understand that you are agreeing a private limit rather than invoking a standard.

Why a Cosmetic Needs the Lining in Its Safety Report

For a balm, a salve or a solid perfume, the food-contact rules are not the operative ones — Regulation (EC) No 1223/2009 on cosmetic products is. Two provisions in it name packaging directly, and both sit in the document a Responsible Person has to hold.

Article 17, on traces of prohibited substances, permits the non-intended presence of a small quantity of a prohibited substance stemming from impurities, the manufacturing process, storage, or — the words are explicit — “migration from packaging”, where it is technically unavoidable in good manufacturing practice, and only if the result still satisfies Article 3 safety. Annex I, Part A, point 4 is headed “Impurities, traces, information about the packaging material” and requires the relevant characteristics of packaging material, in particular purity and stability.

3-Field CPSR Packaging Entry

Field the safety assessor will ask for	What to obtain from your tin supplier	On file
Identity of the contact surface	Bare aluminum, or the lacquer resin family and product code — body and lid liner separately	______
Purity	The supplier’s declaration for the lacquer, with any restricted-substance statements (BPA, BADGE)	______
Stability	Your own 4-Week Accelerated Compatibility Hold result with the finished formulation	______

The third field is the one no supplier can give you, because it depends on your formulation and not on their tin. That is the argument for running the hold yourself rather than asking for a certificate.

Worth knowing alongside it: ISO 22715:2006, Cosmetics — Packaging and labelling, was confirmed on review in 2022 and remains current, but it is a packaging-information and labelling standard. It does not set migration or lining-compatibility requirements, so it is not the reference for this question even though it is the one most often quoted.

If you are the Responsible Person for an EU cosmetic, request the lacquer declaration at the quotation stage — assembling the safety report after production has started is where launch dates go.

A Worked Example, From Formulation to Specified Lining

A 100 g water-containing body cream, pH 5.5, containing 0.8% essential oil blend, in our 84 mm body, sold in the EU and the US, target shelf life 24 months.

6-Step Lining Selection Trace

Step	Input	Working	Output
1	Free water present	Reference chart row 3	Lining required — unlined is not an option
2	Essential oil at 0.8%	Solvent resistance becomes the deciding property, not pH	Chemistry chosen for solvent resistance; solvent-rub result required with the solvent and rub count stated
3	Dual market	2-Market Lining Legality Gate	BPA excluded by the EU rule; one lacquer specified for both markets
4	24-month shelf life	24 months = 104 weeks; at Q10 = 2 and 55 °C the factor is 8, so 104 ÷ 8 = 13 weeks	A 4-week hold covers roughly 8 months, so extend to 13 weeks for full-life cover, or accept 4 weeks as a screening test
5	Cosmetic, EU	3-Field CPSR Packaging Entry	Lacquer declaration obtained at quotation; hold result becomes the stability evidence
6	Build fixed	3-Layer Coating Build Register completed with film weight tolerance	Lining specified by chemistry, film weight and cure — auditable at incoming inspection

Step 4 is where most programmes make a defensible compromise. Thirteen weeks is a long time to hold a launch. Running four weeks as a screening test to eliminate obviously wrong chemistries, then running the full thirteen in parallel with tooling, is the usual answer — and it only works if you start the hold at the quotation stage rather than after approval.

Send us the formulation and the target shelf life at enquiry, and we will tell you which hold duration your shelf life actually requires before you commit to a lacquer.

2026 Compliance Pressure: The EU BPA Deadline Has Already Passed

This is the item to check this quarter, because the date is behind us rather than ahead.

Regulation (EU) 2024/3190 entered into force on 20 January 2025. Its transitional provisions allowed single-use final food-contact articles made with BPA to be placed on the EU market until 20 July 2026. That date has passed. Two extensions remain, and both are narrow: to 20 January 2028 for single-use articles for the preservation of fruit, vegetables or fishery products, and — the one that matters for metal — for single-use final articles where a varnish or coating manufactured using BPA has been applied only to the exterior metal surface. Repeat-use articles ran to 20 July 2026, with professional food-production equipment to 20 January 2028 and a final market date of 20 January 2029.

Three practical consequences for anyone buying lined tins into the EU right now:

• A declaration citing Regulation (EU) 2018/213 and its 0.05 mg/kg migration limit is citing a repealed instrument. That regulation was repealed by Article 13 of 2024/3190.
• The exterior-surface extension does not help an interior lining. If the BPA coating is inside the tin, the single-use deadline has passed.
• Filled and sealed products already on the market could be distributed until stocks were exhausted within twelve months of the relevant expiry — so stock in the channel and stock you are buying now are in different positions.

Meanwhile the US position has not moved: FDA continues to authorise BPA-based epoxy can linings. If your supplier’s standard lacquer is BPA-based because their main market is the US, that is an entirely rational choice on their part and an unusable one on yours.

Ask your current supplier, in writing and this quarter, whether the interior lacquer on your EU-bound SKUs is manufactured using BPA — and get the answer as a document rather than an email reply.

References

1. Regulation (EC) No 1935/2004 of the European Parliament and of the Council of 27 October 2004 on materials and articles intended to come into contact with food. Consolidated text of 27 March 2021; Article 3 quoted above. eur-lex.europa.eu (PDF)
2. Commission Regulation (EU) No 10/2011 of 14 January 2011 on plastic materials and articles intended to come into contact with food. Consolidated text of 20 January 2025; Article 2(3) quoted above. eur-lex.europa.eu
3. Commission Regulation (EU) 2024/3190 of 19 December 2024 on the use of bisphenol A (BPA) and other bisphenols … amending Regulation (EU) No 10/2011 and repealing Regulation (EU) 2018/213. eur-lex.europa.eu/eli/reg/2024/3190
4. Commission Regulation (EC) No 1895/2005 of 18 November 2005 on the restriction of use of certain epoxy derivatives in materials and articles intended to come into contact with food. food.ec.europa.eu — FCM legislation
5. Council of Europe Resolution ResAP(2004)1 on coatings intended to come into contact with foodstuffs, adopted 1 December 2004, and its Policy Statement concerning coatings, version 3, 12 February 2009. Recommendations, not law. rm.coe.int
6. 21 CFR 175.300, Resinous and polymeric coatings, US Food and Drug Administration. ecfr.gov
7. 21 CFR 176.170(c), Table 1 (types of raw and processed foods) and Table 2 (conditions of use) — the taxonomy cross-referenced throughout the FDA indirect-additive regulations. ecfr.gov
8. FDA, Bisphenol A (BPA): Use in Food Contact Application. fda.gov
9. Regulation (EC) No 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products (recast). Consolidated text of 1 September 2025; Article 17 and Annex I Part A point 4 quoted above. eur-lex.europa.eu/eli/reg/2009/1223
10. ISO 22715:2006, Cosmetics — Packaging and labelling. Confirmed on review 2022. iso.org/standard/36436.html
11. ASTM D3359-23, Standard Test Methods for Rating Adhesion by Tape Test. store.astm.org/d3359-23.html
12. ISO 2409:2020, Paints and varnishes — Cross-cut test, 5th edition. iso.org/standard/76041.html
13. ASTM D5402-19(2024), Standard Practice for Assessing the Solvent Resistance of Organic Coatings Using Solvent Rubs. store.astm.org/standards/d5402
14. ASTM D5162-24, Standard Practice for Discontinuity (Holiday) Testing of Nonconductive Protective Coating on Metallic Substrates. store.astm.org/d5162-24.html
15. German Federal Institute for Risk Assessment (BfR), BfR Recommendations on Food Contact Materials — checked for a can-lacquer recommendation; Recommendation XIV is Polymer Dispersions. empfehlungen.bfr.bund.de

How the Numbers in This Article Were Calculated

The acceleration factor is the Q10 approximation from chemical kinetics: reaction rate is taken to double for each 10 °C rise, so the factor is 2 raised to the temperature difference divided by ten. Q10 = 2 is a convention, not a measured property of any particular formulation; real activation energies vary, and a system whose failure mode is physical rather than chemical — phase separation, liner creep — may not follow it at all. Accelerated holds are a screening tool that predicts. They do not replace real-time stability data, and no regulator accepts them as equivalent.

The 55 °C hold temperature and the four-week duration are common industry choices, selected here because they are practical with an ordinary laboratory oven. A temperature high enough to melt or phase-separate a formulation produces a failure that tells you nothing about the lining; check the formulation’s own thermal limits before choosing a hold temperature.

Regulation titles, article numbers, transitional dates and standard designations were checked against the issuing bodies’ own published texts — EUR-Lex, eCFR, FDA, ISO and ASTM — in September 2026. Regulatory transition dates in particular move; take them from the current consolidated text rather than from this article, and note that national provisions under Article 6 of Regulation 1935/2004 may add requirements this article does not cover.

Frequently Asked Questions

Do all aluminum tins need an interior coating?
No, and assuming they do is as expensive as assuming they do not. Anhydrous products — solid balms, waxes, poured candles, dry tea — are commonly packed in unlined aluminum. The decision turns on free water, pH and solvent content, and it should be recorded as a decision rather than a default either way.

Is a Regulation 10/2011 declaration valid for a lined tin?
No. Article 2(3) of Regulation (EU) No 10/2011 states that it is without prejudice to provisions applicable to printing inks, adhesives or coatings, and a lacquer on metal is a coating. Ask instead for a declaration against Article 3 of Regulation (EC) No 1935/2004 together with the BPA and epoxy-derivative positions.

Is BPA still allowed in can linings?
Not in the EU. Regulation (EU) 2024/3190 prohibits it in varnishes and coatings, and the transition for single-use articles ended on 20 July 2026, with a narrow extension only where the BPA coating is on the exterior metal surface. In the US, FDA continues to authorise BPA-based epoxy linings for the currently approved uses.

What is the difference between food grade and food contact compliant?
“Food grade” is an adjective with no legal definition. “Compliant” means a named instrument, for a named food type, under a named condition of use, with test evidence behind it. If a declaration does not contain those four things, it has not answered the question.

How long should I run a compatibility test?
Divide your target shelf life by the acceleration factor. At 55 °C against a 25 °C ambient the factor is 8, so a 24-month shelf life implies about 13 weeks. Four weeks is a legitimate screening test that covers roughly eight months; it is not full-life cover.

Does the lid liner need the same compliance documents as the body?
Yes, and it is the most commonly missed item. The liner is a different material from a different supplier and is often outside the scope of the declaration on file — while being in full contact with the product in any tin that is stored on its side or inverted.

Can you test a lacquer with an enamel rater and call it a standard test?
No. The enamel rater is an industry instrument method with no ASTM, ISO or DIN designation, and its acceptance limits are set in supply contracts rather than by any standard. Report the milliamp figure and the contractual limit, and do not attach a standard number to it.

Getting a Lining Specified

Send your formulation — water content, pH, essential oil percentage, preservative system — your target shelf life and your destination markets. We will tell you whether the product needs a lining at all, which chemistry the formulation points to, and which declarations you will need for each market. If your formulation is anhydrous and does not need one, we will say so rather than sell you one.

Send your formulation for a lining check — 5,000 pcs minimum per SKU, 15–20 days production after artwork approval, samples available before bulk. See also our aluminum tins for cosmetics and our screw-top body specifications.