Lanolin (wool wax): SAP value and fatty acids
Lanolin (wool wax) has a saponification value of 97.5 mg KOH/g. One gram needs 0.070 g of sodium hydroxide (NaOH) for bar soap or 0.098 g of potassium hydroxide (KOH) for liquid soap to turn fully into soap, before any superfat.
Key numbers
- SAP, NaOH
- 0.069506 g per g oil
- SAP, KOH
- 0.0975 g per g oil
- Saponification value
- 97.5 mg KOH/g
- INCI name
- Lanolin
Example: 100 g of Lanolin (wool wax) with no superfat needs 7.0 g of 100% NaOH, or 9.8 g of 100% KOH. A 5% superfat uses 5% less.
In soap
Lanolin (wool wax) is left out of the soap-quality scores in Soap Ledger: it is mostly not ordinary oil (a wax, resin, blend or an oil with unusual fatty acids), so those scores would not describe it. It still counts fully in the lye calculation.
Sheep's-wool wax: mostly esters of fatty acids with sterols and fatty alcohols, so a large part stays unsaponified in the bar. SAP is about half that of a normal oil. Treat as a superfat additive. Hydrous lanolin (with water) is lower, 67–79. The pharmacopoeia figures are for solid lanolin; 'liquid lanolin' (lanolin oil) may differ — check the COA. Published sources for this oil differ by more than 3%, so checking your supplier's certificate of analysis matters more than usual.
Sources
SAP value: 97.5 mg KOH/g (USP / Ph. Eur. range midpoint), from Lanolin USP – Sales Specifications (states USP monograph limits), ChemCeed (supplier). Printed value: Saponification Value 90-105 mg KOH/g.
Published values we checked:
- Saponification Value 90-105 mg KOH/g — ChemCeed (supplier)
- 90-105 (anhydrous wool fat) mg KOH/g — Kruidwis (Dutch pharmacy-compounding site)
- NaOH 0.0748 / KOH 0.1054 g alkali per g oil — Certified Lye
NaOH and KOH values are converted from mg KOH/g with the molar masses 39.997 and 56.106 and rounded to 6 decimals, exactly as in the Soap Ledger app. Real oils vary by origin, grade and lot: check your supplier's certificate of analysis. Verify every weight before you make this, and follow lye safety. Not a safety or compliance certification.
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