Myristic acid: SAP value and fatty acids
Myristic acid has a saponification value of 245 mg KOH/g. One gram needs 0.175 g of sodium hydroxide (NaOH) for bar soap or 0.245 g of potassium hydroxide (KOH) for liquid soap to turn fully into soap, before any superfat.
Key numbers
- SAP, NaOH
- 0.174656 g per g oil
- SAP, KOH
- 0.245 g per g oil
- Saponification value
- 245 mg KOH/g
- Iodine value
- 0.3
- INS
- 245
- INCI name
- Myristic Acid
Example: 100 g of Myristic acid with no superfat needs 17.5 g of 100% NaOH, or 24.5 g of 100% KOH. A 5% superfat uses 5% less.
In soap
Its main fatty acids in our cited profile are myristic (98%). The eight fatty acids used in soap-quality scores make up 98% of the profile.
On its own it scores 98 for hardness, 98 for cleansing and 0 for conditioning, with a saturated : unsaturated split of 98 : 0.
A free fatty acid, not a fat; it neutralises lye directly and adds no glycerin. Pure myristic acid needs 245.7 mg KOH/g.
Fatty-acid profile
| Fatty acid | % of fatty acids | Counts toward |
|---|---|---|
| lauric | 0% | hardness, cleansing, bubbly lather |
| myristic | 98% | hardness, cleansing, bubbly lather |
| palmitic | 0% | hardness, creamy lather |
| stearic | 0% | hardness, creamy lather |
| ricinoleic | 0% | conditioning, bubbly and creamy lather |
| oleic | 0% | conditioning |
| linoleic | 0% | conditioning |
| linolenic | 0% | conditioning |
Basis: Supplier specification for Myristic Acid 98% (C14 98% min); myristic set to the 98% minimum and the remaining 2% put in "other".
Soap-quality scores (this oil alone)
| Hardness | 98 |
|---|---|
| Cleansing | 98 |
| Conditioning | 0 |
| Bubbly lather | 98 |
| Creamy lather | 0 |
| Iodine | 0 |
| INS | 245 |
Each score adds up certain fatty acids, the way Soap Ledger scores a whole recipe. They are for comparing recipes; they don't predict how a bar will feel, and they say nothing about safety or skin.
Sources
SAP value: 245 mg KOH/g (JSQI 2021 acid-value range midpoint (pure free acid: SAP = acid value)), from Theoretical SAP of pure lauric acid from molar mass, computed (56106 / molar mass). Printed value: 56106 / 228.37 (C14H28O2) = 245.7 mg KOH/g.
Published values we checked:
- acid value 240～250 mg KOH/g — Ministry of Health, Labour and Welfare (Japan)
- 56106 / 228.37 (C14H28O2) = 245.7 mg KOH/g — computed (56106 / molar mass)
Fatty acids and iodine: Myristic Acid 98% FGK Flakes – Product Data Sheet (Dec 2011), Acme-Hardesty Co. (supplier). Also checked: Ministry of Health, Labour and Welfare (Japan) (Monograph ミリスチン酸 Myristic Acid: "consists mainly of myristic acid"; acid value 240–250, mp 45–56 °C).
NaOH and KOH values are converted from mg KOH/g with the molar masses 39.997 and 56.106 and rounded to 6 decimals, exactly as in the Soap Ledger app. Real oils vary by origin, grade and lot: check your supplier's certificate of analysis. Verify every weight before you make this, and follow lye safety. Not a safety or compliance certification.
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