Why did my homemade shampoo or hair mask separate?
Short answer
Almost always one of three things: the two phases were at different temperatures when combined, the mixing order was wrong, or there was not enough emulsifier. The book's fix is a strict sequential mixing protocol and cycle testing before you call a formula finished.
Explanation
The book gives a general protocol for order of addition, and warns that it is critical: hydrate gums and thickeners in the water phase first, dissolve primary surfactants with gentle heat if needed, add secondary surfactants and conditioners, cool to below 40 °C before adding heat-sensitive actives such as peptides, vitamins and extracts along with fragrance, adjust pH, then incorporate the preservative last.
For emulsions such as the repair mask, both phases must reach the same temperature — 70–75 °C — before they are combined. Adding a cool water phase to a hot oil phase gives an emulsion that looks fine warm and breaks overnight. Phase B goes into Phase A slowly, under a high-shear mixer, for two to three minutes.
Stability is not something you judge by eye on day one. The book asks for cycle testing — alternating hot and cold for 24 to 48 hours each — plus long-term shelf testing at room temperature, watching for separation, colour change, smell and pH drift over weeks.
What to do
- Bring both phases to the same temperature, 70–75 °C, before emulsifying.
- Use a high-shear mixer for the first 2–3 minutes, then switch to gentle paddle stirring as it cools.
- Run a cycle test before scaling a formula up or giving it away.
Source: The Big Book of Homemade Hair Care — The Shampoo Matrix: Beyond Basic Cleansing · The Intensive Repair Hair Mask