The three failure modes
Incomplete wetting. Particles that are not fully wetted by the carrier remain as clusters. The clusters scatter visible light — the opaque film people associate with bad mineral sunscreen — and the UV absorption is lower than the loading suggests.
Re-agglomeration. A dispersion that looks perfect at the mill outlet can reagglomerate in the emulsion over weeks. This is the failure that shows up in stability testing rather than in the first batch, which is what makes it expensive.
Over-milling. More energy is not automatically better. Excessive milling can alter surface chemistry, drive interaction with dispersants, and create a viscosity the emulsion cannot carry.
What we control
Carrier selection, dispersant chemistry and dosage, mill type and residence time, temperature during milling, order of addition, and the point at which the dispersion enters the emulsion. All of these are specified in the process document rather than left to the operator's judgement.
Verification is by particle size distribution after milling, and by film assessment on drawdown. Both are measured per batch. A batch outside specification does not proceed.
Specific instruments, methods and acceptance criteria are shared under NDA.
Why the incoming material matters
Dispersion cannot fix a particle that arrives tightly agglomerated. Low initial agglomeration and a narrow size distribution mean the mill has less work to do — which means lower shear, less dispersant, and a formulation with more room for emollients, film formers and actives.
That is the practical commercial value of our upstream technology arrangement. It is not a marketing point. It changes what the formulator can put in the bottle.