Why a magnetic-closure box needs a food-contact field at all
A rigid set-up box with a hidden magnet is usually bought as packaging, not as a kitchen article, so buyers often assume food-contact language is irrelevant. It becomes relevant the moment the box design puts the product in direct contact with the board, the liner, or a window film — a chocolate assortment in a printed tray, a tea caddy whose inner lid touches the leaves, a gift box with loose confectionery. In those layouts the packaging is a food-contact material, and the phrase "food-contact suitability" in a datasheet is a claim that should be traceable to a defined material, a defined test condition and a defined regulatory route.
This guide is about reading that claim. It does not tell you which box to buy; it tells you what has to be on the page before the claim means anything.
Parameter definition: what "suitable for food contact" resolves into
A usable specification does not stop at "food grade". It resolves into four separate statements, each of which can be checked:
- Which component is in scope. Boxboard or greyboard, the printed or laminated surface, the liner paper, any plastic window film, and the adhesive used. A statement that only names "the box" hides the fact that the film and the adhesive are different materials with different compliance routes.
- Which regulatory route is being declared. For plastics in the EU this is typically Regulation (EC) No 10/2011; for paper and board there is no harmonised EU measure, so suppliers usually point to national rules (for example the German BfR recommendation for paper and board) plus a declaration of compliance. In the US the routes are the food-additive regulations in 21 CFR Parts 170–189, prior sanctioned status, or an effective Food Contact Notification, which is specific to the notifier and the described use.
- What contact scenario is covered. Direct dry contact, direct contact with fatty or aqueous food, or indirect contact through an inner bag. The scenario decides the test conditions, so a certificate without a scenario cannot be matched to a use.
- Whether the metal magnet assembly is excluded and why. Magnets sit inside the wall or behind a liner; a datasheet should say whether the magnet and its coating are separated from the food-contact surface by a functional barrier, and what that barrier's thickness and composition are.
Units and test conditions: the numbers behind the claim
The reason to insist on test conditions is that migration results are meaningless without them. Under EU Regulation 10/2011, overall migration is expressed as 10 mg per dm² of food-contact surface, or 60 mg per kg of food for certain articles and for small articles where the surface-to-volume ratio is unfavourable. Those are limit values, not results; a datasheet should show which of the two expressions the laboratory used and the measured value against it.
Results also depend on the food simulant and the test conditions chosen for the intended contact. Regulation 10/2011 sets out a family of simulants — aqueous, acidic, alcoholic and fatty, plus the dry-food substitute — and a table of contact conditions expressed as time and temperature (short-term hot fill, long-term room-temperature storage, and so on). The same coating can pass an aqueous simulant and fail a fatty one, so a datasheet that reports "passed migration testing" without naming the simulant and the time/temperature combination is not comparable with any other supplier's sheet.
Specific migration limits add a second layer: individual substances, such as certain monomers, additives and processing aids, have their own limits in mg per kg of food, and primary aromatic amine and heavy-metal restrictions apply to some colorants. A food-contact declaration of compliance should list the restricted substances relevant to the materials used rather than assert blanket compliance.
How to read the specification line by line
Take the datasheet's compliance section and run this sequence:
- Match material to route. If the sheet cites 10/2011 for a coated board, check that the plastic coating and lamination, not the paper core, is what the citation covers. Paper and board need their own statement.
- Check the FDA basis clause. "FDA compliant" is incomplete without naming the regulation section or the FCN number. An FCN covers a named substance for a named use by a named notifier; if your box maker buys the coating from a converter, ask for the FCN reference or the 21 CFR citation that the converter's own declaration uses.
- Look for the declaration of compliance details. In the EU a declaration of compliance for plastics must identify the materials, the intended use, the migration test data and any restrictions. If a supplier sends a one-page certificate with a logo and no substance list, treat the claim as unverified.
- Confirm the test article. Was the laboratory testing a flat sample of the coated board, or a finished box including adhesive and magnet pocket? Results from a flat sample do not automatically transfer to a folded, glued construction.
- Note the date and version. Regulations are amended. Record which version of the declaration you hold and when it was issued, so a later redesign of the coating does not silently invalidate your file.
Comparison caveats when you benchmark two suppliers
- Different simulants and contact conditions are not comparable, even when both sheets say "passed". Normalise to simulant plus time and temperature before drawing a conclusion.
- Overall migration and specific migration answer different questions. A sheet reporting only overall migration says nothing about a substance with its own limit.
- Sensory testing (odour and taint) is a separate evaluation from legal compliance. A board can be fully compliant and still taint a delicate product; if the product is aroma-sensitive, ask for the sensory assessment separately.
- Certification schemes and third-party marks are not substitutes for a declaration of compliance with the underlying regulation. They document a management system, not the migration data.
- Declared grammage and coating weight affect barrier performance; two boxes with the same board grade but different coating weights should not be assumed to have equivalent migration behaviour.
Compatibility and limits
Food-contact suitability is one property among many in a magnetic-closure box specification, and it interacts with the others. Lamination and varnish chosen for scuff resistance may change the migration profile; recycled fibre content can raise mineral-oil hydrocarbon questions that the compliance declaration may not cover; a window film that satisfies the plastic rules may still need its own adhesive evaluation. The box's structural features — magnet pocket, ribbon, foam insert — each add a material that sits close to the food and deserves its own line in the declaration. Where the intended use is dry, non-fatty food in an inner bag, the appropriate statement is narrower and simpler; do not let a broad "food safe" headline substitute for that narrower statement.
Finally, remember that compliance is declared by the supplier for a defined use. If you change the product, the filling, the storage temperature or the inner packaging, the declaration you already hold may no longer describe your situation.
Source and version record
When you file the paperwork, record: the regulation and its consolidated version or amendment cited; the FCN or 21 CFR section referenced for US routes; the simulant and contact conditions used in testing; the laboratory report number and date; the identity of the test article (flat sample versus finished box); and the issue date of the declaration of compliance. Keeping this record is what allows you to re-verify the claim in two years, when the coating supplier, the converter or the regulation may all have changed.