Guide topic
Cold-Process Soap
Plain-English, source-cited guides to cold-process soap chemistry.
Guide
Soap lye calculator (NaOH & KOH)
Add your oils by weight for the exact NaOH or KOH grams, water, and superfat discount — free, 32 oils, cited SAP values.
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Guide
Lye calculator basics: SAP values
Saponification values, why every oil needs a different amount of NaOH, and how superfat changes the number.
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Guide
Superfat and water, explained
What superfat (lye discount) and water amount actually do — the three ways to express water, and how each affects your bar.
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Buying guide
The best soap making supplies (2026)
lye, base oils, molds, and the scale that keeps a batch on-recipe.
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The app for this
Trace: Soap & Lye Calculator
A cold-process soap calculator with cited chemistry: SAP-based lye and water for any oil blend, superfat, quality bounds and fragrance caps that name their source, plus a multi-batch cure tracker. No subscription, no ads, no scanner, works offline.