Castor Oil for Soap Making
Castor Oil is a liquid specialty oil dominated by ricinoleic (90%), oleic (4%), linoleic (4%). Rich in ricinoleic acid, it stabilizes and boosts lather. It is almost always used as a supporting oil rather than a base.
Quick Facts
How Much Lye for Castor Oil?
With a SAP value of 0.129, fully saponifying castor oil takes 0.129 grams of sodium hydroxide per gram of oil (at 0% superfat):
| Oil amount | NaOH (0% superfat) | KOH (liquid soap) |
|---|---|---|
| 100 g | 12.9 g | 18.1 g |
| 500 g | 64.5 g | 90.5 g |
| 1000 g | 129 g | 181 g |
Real recipes use a superfat discount (typically 5%) and almost always blend several oils. Always run your full recipe through the Soaply lye calculator rather than weighing lye from a single-oil table.
Predicted Bar Properties
Derived from the fatty acid profile, for a bar made of 100% castor oil:
Fatty Acid Profile
| Fatty acid | Percentage |
|---|---|
| Ricinoleic | 90% |
| Oleic | 4% |
| Linoleic | 4% |
Substitutes for Castor Oil
The closest matches by fatty acid profile, which is what actually determines how an oil behaves in soap. Swap by weight and re-run the lye calculation, since SAP values differ:
Build a recipe with Castor Oil
The free Soaply calculator handles the lye math, water, superfat, and property predictions for any blend of 100 oils.
Open the lye calculatorMore Specialty Oils
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