Soap superfat explained: lye discount and added fat
What 5% superfat means, why two methods produce different batch weights, and how to choose deliberately.
Superfat is a formulation choice
Superfat describes fat intentionally left beyond the amount the entered alkali can saponify. It can create a gentler-feeling bar, but excessive superfat may reduce lather, soften soap, or shorten shelf life.
Method one: lye discount
The base oils remain 100% of the oil formula. The calculator reduces the theoretical alkali by the selected percentage. A 5% setting does not make the entered oils total 95%; it means the alkali is discounted relative to full saponification.
Method two: added superfat
The calculator uses full alkali for the base oils, then plans a separate fat as a percentage of base-oil weight. With 1,000 g of base oils and 5% added superfat, the additional fat is 50 g and the oil-containing batch becomes 1,050 g.
- This method is not limited to hot process.
- Adding a named fat does not guarantee that only that fat remains unsaponified in every process.
- Include the extra fat in mold and batch-weight planning.
Choose based on the formula you intend to make
Use lye discount when you want the classic reduced-alkali interpretation. Use added superfat when a separate measured addition is part of your process. Label the method clearly in the production sheet so another maker can reproduce it.