What is a macerated oil?
Short answer
An oil in which dried botanicals have been steeped so it takes up their fat-soluble compounds, like calendula-infused oil.
Explanation
Maceration means steeping thoroughly dried plant material in a stable carrier oil. Fresh herbs bring in water, which leads to rancidity and mold. Stable carriers include fractionated coconut, jojoba, high-oleic sunflower and refined olive oil. Avoid flax, hemp, walnut and evening primrose, which oxidize fast.
In soap, a macerate can replace part of the oil base or be used as a post-trace superfat. The Rosemary & Citrus bar uses rosemary-infused olive oil, and the Fresh-Cut Rose bar uses rose macerate.
What to do
- Cold method: fill a jar ½–⅔ with dried herb, cover with at least an inch of oil, and keep it cool and dark for 4–6 weeks, shaking every few days. Then double-strain.
- Heat-assisted: 1–2 weeks in the sun, or an oven at 50 °C or less for 2–8 hours, then strain immediately. Some cloudiness is normal.
- Store in dark glass somewhere cool; it keeps 6–12 months, longer with rosemary extract or vitamin E.
Source: The Big Book of Homemade Soap — Macerated Oils (Infused Oils) for Soap & Skin Care