Emulsion
Emulsion — a stable blend of two liquids that normally do not mix, most often oil and water, held together with the help of an emulsifier. In skincare this structure gives lotions and creams their smooth, spreadable texture and lets water-loving and oil-loving ingredients coexist in one product. Emulsions are commonly described as oil-in-water or water-in-oil depending on which liquid forms the continuous phase.
Key points
- An emulsion combines two immiscible liquids, typically oil and water, into one uniform-looking mixture.
- An emulsifier is needed to keep the droplets dispersed and stop the phases from separating.
- Oil-in-water emulsions usually feel light, while water-in-oil emulsions tend to feel richer and more occlusive.
- Most lotions, creams, and many serums are emulsions that carry both water- and oil-soluble ingredients.
Frequently asked
What is the difference between oil-in-water and water-in-oil emulsions?
In oil-in-water emulsions oil droplets are dispersed in water and tend to feel lighter, while in water-in-oil emulsions water is dispersed in oil, giving a richer, more occlusive feel.
Why do emulsions sometimes separate?
Separation happens when the emulsifier can no longer keep the two phases mixed, often due to temperature changes, aging, or an unstable formula.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
