Japan wax (sumac wax): SAP value and fatty acids
Japan wax (sumac wax) has a saponification value of 215 mg KOH/g. One gram needs 0.153 g of sodium hydroxide (NaOH) for bar soap or 0.215 g of potassium hydroxide (KOH) for liquid soap to turn fully into soap, before any superfat.
Key numbers
- SAP, NaOH
- 0.15327 g per g oil
- SAP, KOH
- 0.215 g per g oil
- Saponification value
- 215 mg KOH/g
- INCI name
- Rhus Succedanea Fruit Wax
Example: 100 g of Japan wax (sumac wax) with no superfat needs 15.3 g of 100% NaOH, or 21.5 g of 100% KOH. A 5% superfat uses 5% less.
In soap
We don't have a sourced fatty-acid profile for it yet, so Soap Ledger shows no soap-quality scores for recipes that use it. The lye calculation still works.
Despite the name, Japan wax is mostly a fat (glycerides of palmitic acid, plus some dibasic acids), not a wax ester, so it saponifies almost fully. Unsaponifiable matter ≤1% (JSQI). Supplier values run lower than handbooks; sources disagree by ~13%. Published sources for this oil differ by more than 3%, so checking your supplier's certificate of analysis matters more than usual.
Sources
SAP value: 215 mg KOH/g (JSQI 2021 range midpoint), from Japan Wax (chemical index entry; Merck Index–derived), DrugFuture Chemical Index Database. Printed value: 217-237 mg KOH/g.
Published values we checked:
- 205～225 mg KOH/g — Ministry of Health, Labour and Welfare (Japan)
- 217-237 mg KOH/g — DrugFuture Chemical Index Database
- 220 mg KOH/g — Wikipedia
- 180 - 220 mg KOH/g — From Nature With Love (soap/cosmetic supplier)
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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