Cottonseed oil in soap making
Published by The Soap Brain Team
Cottonseed oil is a conditioning soap-making oil rich in linoleic acid (52%). A gram of it turns to soap with about 0.137 g of NaOH (lye). It makes a mild, gentle bar and pairs well with a harder, cleansing oil. Most soapers use it at 10–20% of their oils.
Fatty-acid profile
Cottonseed oil is a gentle, conditioning oil, mostly unsaturated fatty acids that leave a mild, moisturising bar with a softer, lower lather. It pairs naturally with a harder, more cleansing oil to firm the bar up and add bubbles. Because its polyunsaturated (linoleic/linolenic) share is on the higher side, watch the total across the whole recipe and consider a modest antioxidant to guard against rancidity and DOS.
Cottonseed oil is about 26% saturated fat and 69% unsaturated — that unsaturated majority is what makes it conditioning and slower to trace, but softer on its own.
| Fatty acid | Share | What it does in soap |
|---|---|---|
| Linoleic acid | 52% | a polyunsaturated fatty acid that is very conditioning but oxidises readily — a driver of DOS (dreaded orange spots) at high levels |
| Palmitic acid | 23% | a saturated fatty acid that builds a hard, long-lasting bar with a stable, creamy lather |
| Oleic acid | 17% | a monounsaturated fatty acid that makes a gentle, conditioning, moisturising bar with a slick, lower lather and a slower trace |
| Stearic acid | 2.3% | a saturated fatty acid that adds hardness and a thick, stable lather; a large share can speed up trace |
| Myristic acid | 0.8% | a hard, cleansing, bubbly saturated fatty acid that usually travels alongside lauric acid |
Cottonseed oil in the bar
Expect a dense, low-bubble, creamy lather from Cottonseed oil — rich and steady rather than foamy. Pairing it with a bubbly oil adds the fluffy bubbles it lacks.
Cottonseed oil traces at a fairly typical pace; how fast the whole batch moves will depend mostly on the other oils, your temperatures and any fragrance you add.
In a blend Cottonseed oil is the conditioning, skin-feel component and can often make up the bulk of the oils. Add a firmer, more cleansing oil — coconut, palm or a hard butter — to bring hardness and bubbles the finished bar would otherwise miss.
Closest substitutes for Cottonseed oil
Out of Cottonseed oil? These oils behave most like it in a bar — ranked by how close their hardness, cleansing and conditioning profile and lye (SAP) requirement are. The numbers are predicted properties for a 100% single-oil bar, not a safety guide; always recalculate the lye when you swap an oil.
| Oil | Hardness | Cleansing | Conditioning | SAP (NaOH) |
|---|---|---|---|---|
| Cottonseed oil (this oil) | 26 | 1 | 69 | 0.137 |
| Baobab oil (refined) | 24 | 0 | 70 | 0.135 |
| Tamanu (foraha) oil | 30 | 0 | 68 | 0.139 |
| Rice bran oil | 23 | 0 | 75 | 0.133 |
| Marula oil | 22 | 0 | 76 | 0.139 |
Using Cottonseed oil in a recipe
One gram of Cottonseed oil needs about 0.137 g of NaOH (sodium hydroxide) to turn fully to soap, within a documented range of 0.135–0.141 g/g across sources. The calculator below uses this value; always confirm the lye weight before you mix.
Its iodine value is about 109 — a higher value, pointing to a softer, more conditioning bar that is more prone to rancidity (DOS). Iodine value is only a rough guide, not a hard rule, but it gives you a feel for how a bar built around this oil will wear.
Most soapers use Cottonseed oil at roughly 10–20% of their oils.
Maker's note: Historic Marseille-style soaping oil; mild and conditioning. High in linoleic acid, so keep it a minor oil and pair it with harder ones to protect shelf life.
Calculate lye for Cottonseed oil
The calculator below is pre-loaded with Cottonseed oil. Enter your weights, add other oils, and it works out the exact NaOH (lye) weight, water and quality numbers. Always weigh lye, oils and water — never measure by volume, wear gloves and eye protection, and add lye to water (never the reverse).
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Where these numbers come from
Every figure on this page is backed by at least two independent references, listed below — so you can check our work instead of taking our word for it.
- Codex Alimentarius CXS 210-1999 — Named Vegetable Oils (Tables 1–2) — SAP 189–198 mg KOH/g; Table 1 fatty acids: C14:0 0.6–1.0, C16:0 21.4–26.4, C18:0 2.1–3.3, C18:1 14.7–21.7, C18:2 46.7–58.2, C18:3 ND–0.4
- From Nature With Love — Saponification Chart — SAP range
- The Conscious Life — Cottonseed oil (USDA SR28) — palmitic 22.7, stearic 2.3, myristic 0.8, oleic 17.0, linoleic 51.9 g per 100 g of oil — a ~95% basis, the glycerol backbone being the rest
SAP data last updated · 51 oils covered.
Cottonseed oil soap FAQ
- Can you make soap with 100% Cottonseed oil?
- It is not recommended. Cottonseed oil shows its best in a blend, usually up to about 20% of the oils. On its own the bar would be unbalanced — too soft or low-lathering for everyday use.
- What superfat should I use with Cottonseed oil?
- A 5% superfat is a safe, common starting point for recipes using Cottonseed oil; adjust to taste once you know how the finished bar feels. Never drop to 0% or below without a deliberate reason — the calculator will ask you to confirm it.
- Does Cottonseed oil speed up or slow down trace?
- Cottonseed oil traces at a fairly typical pace; how fast the whole batch moves will depend mostly on the other oils, your temperatures and any fragrance you add.