The label decision comes before the artwork
In most sourcing timelines, the warning label is treated as artwork: something added at the packaging stage, after the shell colour and the gift box are settled. In California that order is backwards. The warning obligation follows from an exposure assessment of the materials in the product, and the assessment has to happen while the bill of materials is still open. If it happens after the tooling is cut, a required warning can force a sticker onto a box that was designed without space for one, or a reprint of a manual that has already been ordered.
This article is a checklist for that decision. It is written for buyers handling a charger, a heating element and a moulded shell, not for a laboratory, and its consistent conclusion is that the determination belongs to a qualified assessor, not to a supplier's marketing department.
The decision path
Checklist steps and the document behind each
| Step | Question to answer | Document that answers it | Who confirms |
|---|---|---|---|
| 1 | Which materials and components are in the product, down to the overmould, adhesive and solder? | Full bill of materials with material declarations | Supplier engineering |
| 2 | Has an exposure assessment been done for the intended use, including prolonged skin contact? | Exposure assessment report with the use scenario stated | Qualified assessor |
| 3 | Does the assessment conclude that a warning is required, and for which exposure route? | Signed assessment conclusion, not a summary email | Assessor, reviewed by your counsel |
| 4 | If a warning is required, what wording and format applies? | Proposed label text with the basis for the chosen format | Counsel plus assessor |
| 5 | Where will the label appear: shell, retail box, manual, or a combination? | Artwork proof showing position and size | Supplier plus your packaging team |
| 6 | Does the label survive handling, and is it legible after abrasion? | Label durability test record | Supplier quality |
A supplier who can walk through all six rows has engaged with the question. A supplier who answers row one with "our product is compliant" has skipped to the conclusion without producing the evidence that supports it.
Documents to request
The first is a material declaration covering the parts a buyer rarely sees: the adhesive that bonds the heating element, the potting or conformal coating on the control board, the pigment in the overmould, the bead of the NTC thermistor, the housing of the OTP protector, and the plastic of the battery compartment. These are the locations where a listed substance is most likely to sit, and they are the locations a supplier's own summary tends to omit.
The second is the exposure assessment itself, with the use scenario written down. A hand warmer is held against skin for long periods, which is a different exposure pattern from a device that is touched briefly, and an assessment written for the wrong scenario will not answer the question. Ask what scenario the assessor assumed and whether it matches how the product is actually used.
The third is the label artwork with position marked, and the fourth is the durability record for the label. The fifth is a change-control statement: what material substitution would invalidate the assessment and require a new one.
Placement, language and durability
Placement is a practical decision with compliance consequences. On a sealed hand warmer, the shell may offer a small recess for a label; the retail box offers more space but is discarded before use; the manual is durable but easy to ignore. Many products carry a combination, and the combination should be decided once and recorded, because moving a label between the shell and the box changes what the user actually sees at the point of use.
Language and legibility belong together. A warning set in type too small to read, or printed in a colour that fades, satisfies a checklist and defeats the purpose. Ask for a proof at production size rather than a print file viewed on screen, and ask how the label is protected against the abrasion of a pocket or a bag.
A warning label ≠ a compliance certificate
The boundary in one sentence: a warning label does not make a product compliant, and the absence of a warning does not prove that no warning was required. The label is the output of a decision; the decision is what a buyer should be buying, along with the documents that support it. A supplier who prints a label to end a conversation has given you an artefact without a rationale.
The second boundary is jurisdictional. This is a California question and nothing in this article answers a European, Japanese or Korean requirement. A product can carry a US warning and still need a completely different file set for another market, and the two should be tracked as separate lines in the compliance matrix rather than assumed to travel together. For that wider view, see the certification document matrix by market and the certification wall reality check.
Five questions for the supplier
- Can you provide a full material declaration that includes the element adhesive, the board coating, the overmould pigment and the solder? The omissions are usually in exactly those four places.
- Has an exposure assessment been performed, and what use scenario did it assume? Prolonged skin contact is the scenario that matters for this product.
- Who signed the assessment conclusion, and can you share the conclusion page rather than a summary? A signature and a scope statement are what make it reviewable.
- Where is the warning applied, and can you send a production-size artwork proof with the position marked? Screen proofs hide legibility problems.
- What material or component change would trigger a new assessment, and how is that tracked? A short written answer here is worth more than any certificate scan.
Next step
Run the six-row checklist before the packaging artwork is released, and keep the assessment together with the sample approval file, which the golden sample signoff form sets out, so a later material change cannot bypass it. Where the assessment result is ambiguous, the correct move is a question to the assessor and to your own counsel, not a decision by the supplier. For the file set on the European side, see REACH SVHC documents to request and GPSR technical file and responsible person. To have the checklist applied to a specific configuration, start at contact.
Written for the Emberly heating-element programme. Specifications are illustrative; confirm every figure against a supplier test record.