Mixture in mixture: using a supplier's UFI in your own dossier

Our page on UFI confidentiality introduces this mechanism from the disclosure side; this page covers how it actually works in practice — what qualifies, what has to be true before you can rely on it, and what to do when it is not available.

What a MiM is

A mixture in mixture, usually shortened to MiM, is any component of your product that is itself a formulated mixture rather than a single substance — a masterbatch, a fragrance compound, a resin system, a pre-blended additive package bought in from another company rather than assembled from raw materials on your own line. Most compositions declared in a PCN dossier are a mix of both: some ingredients are straightforward substances with a CAS number and a percentage, and others arrive at your facility already combined by someone else.

The distinction matters because Annex VIII asks you to declare what is in your product down to the substance level, and by default that means expanding every ingredient — including a supplier's mixture — into its own constituent substances. A MiM is the case where that expansion is not required, because a substitute exists.

Using a supplier's UFI instead of a composition

Where a component of your mixture is itself a notified mixture, Annex VIII lets you identify it in your dossier by that supplier's UFI rather than by breaking it down into the substances it contains. You declare the percentage of your product that component makes up, cite the UFI your supplier has already generated for it, and stop there — the sub-composition behind that code stays in your supplier's own dossier, not yours. A poison centre working an emergency call still gets the full picture: your dossier tells them how much of the MiM component is present, and the supplier's own submission, retrievable through the same UFI, supplies the detail of what that component is actually made of.

This is the mechanism that makes the confidentiality described on our UFI confidentiality page workable in a real supply chain — it lets two companies each protect their own formulation from the other while both still meet their individual notification duties in full.

The condition: the MiM must already be notified

Citing a supplier's UFI only works if that supplier has already submitted their own PCN dossier for the mixture you are buying from them. The UFI is a pointer to a record, and if no record exists behind it — because the supplier's mixture was never independently notified — a poison centre calling up that code during an emergency finds nothing. Building your own dossier around a UFI that resolves to an empty file is worse than not citing one at all, because it looks compliant without actually being useful the moment it matters.

In practice this means the MiM route is only available for a genuinely standalone product: something your supplier places on the EU market in its own right, classified for a hazard, and notified under Annex VIII the same way any other mixture would be. A component custom-blended for you alone, sold to nobody else and never separately notified, does not qualify — there is no independent notification for its UFI to point to.

When the MiM approach is not available

Several situations rule it out, and it is worth checking for these before assuming a supplier's code will cover you. A component that is a plain substance rather than a mixture never qualifies — MiM applies to mixtures within mixtures, not to raw materials, however proprietary the grade. A supplier based outside the EU who has never gone through Annex VIII notification has no UFI to offer, since the obligation to notify never attached to their product in the first place. A custom formulation manufactured to your specification alone, with no independent market presence of its own, falls into the same gap described above — it may function like a MiM ingredient, but nothing was ever separately notified for it.

Where the MiM route is not available, the fallback is the standard one: your supplier discloses the full composition of the component to you, under whatever confidentiality terms your commercial agreement provides, and you declare it in your own dossier at the substance level as if you had formulated it yourself. That is more disclosure than either side would prefer, but it is the only route left when there is no notified UFI to substitute for it.

Getting a UFI from your supplier: what to ask for

A UFI handed over verbally or on an invoice is not enough to build a dossier on with any confidence. Ask your supplier for the code in writing, together with confirmation that it corresponds precisely to the grade and batch specification you actually purchase — a supplier with several similar products can otherwise hand over the code for a near-identical but not identical formulation. Ask, too, whether they will notify you if the underlying composition changes, since a reformulation on their side that keeps the same UFI would break the link this whole mechanism depends on; see our decision rules for when a new UFI is needed for the trigger from their side of that conversation.

It is also worth confirming, rather than assuming, that the supplier's mixture is actually in scope for Annex VIII and has genuinely been notified — a UFI-shaped string handed over informally is not proof of a submitted dossier behind it. Where a supplier cannot produce that confirmation, treat the component as undisclosed and fall back to requesting the full composition instead of building a dossier on a code that may not resolve to anything.