Tallow in soap: SAP value, lye amount & what it does
Tallow has a SAP value of 0.141 g NaOH per gram, and it leans toward hardness in the bar. Here are the exact lye numbers and how it behaves.
SAP value & how much lye tallow (Beef) needs
The saponification (SAP) value of tallow (Beef) is 0.141 g NaOH per gram of oil (0.198 g KOH per gram for liquid soap). So 500 g of tallow (Beef) needs about 70 g of NaOH at 0% superfat, or roughly 67 g at a 5% superfat. Always confirm your full recipe in a lye calculator — SAP is an average and lye is unforgiving.
What it brings to the bar
At 100% (a single-oil bar), its fatty-acid profile works out to these SoapCalc-style qualities (typical range in brackets, per Kevin Dunn):
- Hardness: 51 [29–54] — in range
- Cleansing: 3 [12–22] — low
- Conditioning: 44 [44–69] — in range
- Bubbly lather: 3 [14–46] — low
- Creamy lather: 48 [16–48] — in range
How to use it
Tallow is a balanced oil that plays well as a large share of a recipe; pair it to fill whatever quality (harder, more lather, more conditioning) your bar is short on.
FAQ
What is the SAP value of tallow (Beef)?
Tallow has a SAP value of 0.141 g NaOH per gram of oil (0.198 g KOH per gram). Multiply your oil weight by that to get the lye at 0% superfat.
How much lye do you need for tallow (Beef)?
About 70 g of NaOH for 500 g of tallow (Beef) at 0% superfat, or ~67 g at 5% superfat. Always verify the whole recipe in a lye calculator.
Is tallow (Beef) good for soap?
Yes — used correctly. Tallow is a balanced oil that plays well as a large share of a recipe; pair it to fill whatever quality (harder, more lather, more conditioning) your bar is short on.
What you need to soap with it
Cold-process soap is lye chemistry — accuracy and protection matter more than the mold.
- Weigh oils and lye to the gram on a 0.1 g digital scale — soap is made by weight, never volume.
- Use fresh sodium hydroxide (NaOH) lye for hard bar soap; KOH is for liquid soap.
- Always wear splash goggles and nitrile gloves — lye is caustic until the soap fully saponifies.
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Sources
SAP values and fatty-acid profiles are typical published averages; every batch of oil varies slightly, so always run your final recipe through a lye calculator. Lye is caustic — soap at your own risk with proper protection.