Reading the chart
The KOH column is the saponification value divided by 1,000: grams of potassium hydroxide per gram of oil. The NaOH column converts it to sodium hydroxide using their molar masses (× 0.713). Multiply by the oil weight to get the lye needed at 0% superfat.
Sources
- Codex: Codex Alimentarius food standards for named vegetable oils (CXS 210-1999), olive oils (CXS 33-1981), named animal fats (CXS 211-1999) and cocoa butter (CXS 86-1981). These are internationally agreed specification ranges.
- Ph. Eur.: European Pharmacopoeia monograph limits, used for castor oil and beeswax.
- Literature: typical ranges from published studies and supplier specifications, for oils without a Codex standard. These are less certain, so a 5% or higher superfat is advisable.
- Calculated: from the molar mass of the pure compound (stearic acid, 284.5 g/mol, gives 197.2 mg KOH/g). Commercial "stearic acid" is usually a stearic/palmitic blend and needs a bit more lye (about 0.148 g NaOH per g), so check your supplier's figure.
Some popular calculators list lower figures for a few oils, notably palm kernel and grapeseed. The ranges here come from the standards above. If you're converting a recipe from another tool, expect a small change in lye.
Questions
- What is a saponification value?
- The number of milligrams of KOH needed to completely saponify one gram of fat or oil. It reflects the average size of the fatty acid molecules: oils with short-chain fatty acids such as coconut have high values.
- Why are waxes so low?
- Beeswax and jojoba are mostly wax esters plus unsaponifiable matter, so a gram consumes far less lye than a triglyceride oil.
- Is fragrance oil included in the lye calculation?
- No. Fragrance and essential oils are not saponified for lye purposes; add them as a percentage of oils.