Craft & Design
Superfat
The percentage of oils in soap that are left unsaponified — uncombined with lye. Adds moisture and buffers the bar.
View on brothh.comWhat it means
Superfat (also called "lye discount") is the percentage of oils in a cold-process soap recipe that remain unsaponified (not converted to soap) at the end of the reaction. A 5% superfat means 5% of the oils stay as free oil in the final bar, buffering harshness and adding moisture.
Standard ranges: 0-2% gives a strongly cleansing, drying bar (dish soap, heavy grease hands); 3-5% is balanced for most body bars; 6-8% is moisturizing with a softer bar; 10%+ is very conditioning but soft and short-lived.
Examples
5% superfat on 1000g oils
50g free oil remains; lye reduced by enough to leave that 50g uncombined.
Do
- Balance superfat to the oil profile — coconut-heavy bars handle higher superfat; olive-heavy bars stay good at 3-5%.
Don't
- Exceed 10% without knowing — high superfat accelerates rancidity and makes a soft, short-shelf bar.