Castor Oil
The lather booster. Even 5% dramatically increases bubbles and cling. Never use over 15% alone.
INCI: RICINUS COMMUNIS SEED OIL
Specialty OilsVeganPalm-FreeFeatured
Expert-reviewedPublished Mar 2026Updated Mar 2026
SAP (NaOH)
0.1280
SAP (KOH)
0.1800
Recommended Max
10%
Comedogenic
?/5
Cost Tier
Budget
Castor Oil (RICINUS COMMUNIS SEED OIL) is a soap-making oil used in handmade soap recipes. Its SAP values are 0.1280 for NaOH and 0.1800 for KOH, which helps dial in accurate lye amounts.
Typical usage stays below 10% of total oils. In practice, it is beginner-friendly in balanced formulas, vegan, palm-free, usually easy to source at budget-friendly pricing.
Castor Oil has an NaOH SAP value of 0.12800 and a KOH SAP value of 0.18000, meaning approximately 128g of sodium hydroxide saponifies 1kg of this oil. It is typically used at 0–10.00% of total oil weight in cold process soap recipes.
Fatty Acid Profile
Ricinoleic (90.0%)
Oleic (4.0%)
Linoleic (4.0%)
Soap Qualities Contributed
Hardness
0(29–54)
Cleansing
0(12–22)
Conditioning
94(44–69)
Bubbly Lather
90(14–46)
Creamy Lather
0(16–48)
Longevity
0(5–35)
Shaded areas show the ideal range for balanced soap. Values outside these ranges may still produce good soap depending on the overall formula.
Formulation Guidance
Recommended range:0% — 10%
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Recipes using Castor Oil
Triple Butter Luxury
An ultra-rich bar with three butters: shea, cocoa, and mango. This is a showcase bar — silky lather, incredible skin feel, and a beautiful hard bar. The 7% superfat leaves plenty of unsaponified butter on the skin.
Published Mar 19, 2026
Charcoal Detox Bar
A deep-cleansing bar designed for oily and acne-prone skin. High coconut for maximum cleansing, palm for hardness, and a low 3% superfat to keep the bar from feeling greasy. Activated charcoal draws impurities.
Published Mar 19, 2026
Honey Oatmeal Bar
A soothing, skin-loving bar perfect for sensitive or dry skin. The olive-shea base conditions while coconut provides lather. Sweet almond oil adds a delicate, skin-softening quality.
Published Mar 19, 2026
Tallow & Cream
A rich, creamy bar built on beef tallow — the original soapmaking fat. Higher superfat at 8% leaves extra conditioning oils on the skin. Castor oil boosts the lather from the tallow-coconut base.
Published Mar 19, 2026
Related Ingredients
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Palmitic Acid
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