Superfat Explained — Why 5% vs 8% Matters for Your Soap
A detailed guide to superfat calculation, skin benefits, lye calculator settings, and how the superfat percentage impacts your soap recipe.
Superfat is one of the most important variables in cold process soap formulation. It determines how much oil remains unsaponified after saponification.
What Is Superfat?
Superfat refers to the percentage of oils that remain unreacted. By intentionally using less lye than the total SAP value, some oils remain to provide moisturizing benefits.
Why 5% vs 8% Matters
5% Superfat: Harder bars, faster cure, more cleansing, less moisturizing. 8% Superfat: Softer bars, longer cure, more moisturizing, gentler on dry skin.
How Superfat Is Calculated
Lye Amount = (Total SAP Value x (100% - Superfat%)) / 100
Practical Recommendations
Start with 5% superfat as a beginner. Always verify with a lye calculator.
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