Grapeseed oil in soap making
Published by The Soap Brain Team
Grapeseed oil is a conditioning soap-making oil rich in linoleic acid (67%). A gram of it turns to soap with about 0.135 g of NaOH (lye). It makes a mild, gentle bar and pairs well with a harder, cleansing oil. Most soapers use it at 5–12% of their oils.
Fatty-acid profile
Grapeseed 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.
Grapeseed oil is about 11% saturated fat and 85% 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 | 67% | a polyunsaturated fatty acid that is very conditioning but oxidises readily — a driver of DOS (dreaded orange spots) at high levels |
| Oleic acid | 18% | a monounsaturated fatty acid that makes a gentle, conditioning, moisturising bar with a slick, lower lather and a slower trace |
| Palmitic acid | 8% | a saturated fatty acid that builds a hard, long-lasting bar with a stable, creamy lather |
| Stearic acid | 3% | a saturated fatty acid that adds hardness and a thick, stable lather; a large share can speed up trace |
Grapeseed oil in the bar
Grapeseed oil gives a mild, low, slick lather on its own. Blended with a bubbly, cleansing oil it contributes body and mildness while the partner oil supplies the bubbles.
Grapeseed 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 Grapeseed 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 Grapeseed oil
Out of Grapeseed 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) |
|---|---|---|---|---|
| Grapeseed oil (this oil) | 11 | 0 | 85 | 0.135 |
| Sunflower oil (regular/linoleic) | 12 | 0 | 87 | 0.135 |
| Safflower oil (high-linoleic) | 8 | 0 | 85 | 0.135 |
| Sweet almond oil | 7 | 0 | 86 | 0.136 |
| Corn oil | 15 | 0 | 83 | 0.135 |
Using Grapeseed oil in a recipe
One gram of Grapeseed oil needs about 0.135 g of NaOH (sodium hydroxide) to turn fully to soap, within a documented range of 0.134–0.138 g/g across sources. The calculator below uses this value; always confirm the lye weight before you mix.
Its iodine value is about 138 — 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 Grapeseed oil at roughly 5–12% of their oils.
Maker's note: Light, mild conditioning; PUFA-heavy — keep to a minor oil (DOS risk).
Calculate lye for Grapeseed oil
The calculator below is pre-loaded with Grapeseed 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 188–194 mg KOH/g; Table 1 fatty acids: C16:0 5.5–11.0, C18:0 3.0–6.5, C18:1 12.0–28.0, C18:2 58.0–78.0, C18:3 ND–1.0
- SoapCalc oil list — SAP, iodine
- From Nature With Love — Saponification Chart — SAP range
- The Conscious Life — Grape seed oil (USDA SR28) — stearic 2.7, palmitic 6.7, myristic 0.1 g per 100 g of oil (~2.82% of fatty acids) — marginally under Codex's 3.0 floor
SAP data last updated · 51 oils covered.
Grapeseed oil soap FAQ
- Can you make soap with 100% Grapeseed oil?
- It is not recommended. Grapeseed oil shows its best in a blend, usually up to about 12% 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 Grapeseed oil?
- A 5% superfat is a safe, common starting point for recipes using Grapeseed 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 Grapeseed oil speed up or slow down trace?
- Grapeseed 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.