What is an emulsion, and how do I make a cream?
Short answer
A cream is an oil-in-water emulsion: oil droplets held evenly through a water phase by an emulsifier. Both phases are heated to the same temperature and combined under high shear.
Explanation
The book's creams use emulsifiers such as Olivem 1000 or Emulsifying Wax NF (Polawax) at 3–5%, with cetearyl alcohol (1.5–2.5%) to thicken and stabilize.
The method from the Barrier Repair Cream: heat the oil phase to 70–72 °C until clear. Heat the water phase to 70–72 °C as well, holding it there about 5 minutes. With both at the same temperature, pour the oil into the water in a thin stream while mixing at medium speed, then mix at high speed for 3–4 minutes. Cool while stirring slowly. Add actives at 38–40 °C and the preservative at 35 °C, adjust pH, keep stirring down to 25–28 °C, pack, and rest 24 hours.
What to do
- Match the temperatures of both phases before combining.
- For a lighter texture, reduce cetearyl alcohol to 1.5–2%.
Source: The Big Book of Homemade Skin Care — Barrier Repair Cream · Cellular Renewal Elixir