Soybean Oil
Saponification values, fatty acid makeup, and what this oil does in a bar of soap.
Saponification values
Grams of lye needed to saponify one gram of soybean oil. Multiply by your oil weight, then apply your superfat.
- NaOH (bar soap)
- 0.136
- KOH (liquid soap)
- 0.191
- Iodine
- 131
- INS
- 61
INCI: Glycine Soja (Soybean) OilSaponified name (for labels): Sodium Soyate
Fatty acid profile
| Fatty acid | Percentage |
|---|---|
| Linoleic | 50% |
| Oleic | 24% |
| Palmitic | 11% |
| Linolenic | 8% |
| Stearic | 5% |
Soap qualities at 100%
What a bar made entirely of soybean oil would score. Almost nobody soaps a single oil at 100% — this is here so you can see what the oil contributes to a blend. The shaded band is the range most makers aim for in a finished recipe.
What that means in a recipe
Almost no cleansing contribution (0) against high conditioning (82). Gentle on skin, but a bar built mainly on this will be slow to trace, slow to harden, and low on bubbles without something to balance it.
High in polyunsaturated acids (linoleic and linolenic together, 58). These are the ones associated with the orange spots and rancid smell that develop in older bars, so use fresh oil, keep the percentage modest, and do not expect a long shelf life.
A high iodine value (131) points the same way: more unsaturated, softer, and quicker to go off than a saturated fat.
Derived from the numbers above rather than written by hand, so it stays in step with the data. Tendencies, not guarantees — your oils, water, and technique all move the result.
Oils that behave similarly
Closest matches by fatty acid makeup — the usual starting point when you have run out of soybean oil and need a substitute. Check the lye maths again after swapping: SAP values differ even between oils that behave alike.
- Borage OilSAP 0.135 NaOH
- Cherry Kern1 Oil, p. aviumSAP 0.135 NaOH
- Corn OilSAP 0.137 NaOH
- Pumpkin Seed Oil virginSAP 0.139 NaOH
- Black Cumin Seed Oil, nigella sativaSAP 0.139 NaOH