Frankincense oil
Under the IFRA Standards a rinse-off soap may hold up to 32.5 % of this oil, a limit set by its Thujone.
IFRA maximum for soap
Restricted constituents, at the typical levels IFRA's annex gives:
- beta-Thujone
- 0.4 %
Worked out from typical levels. A supplier's certificate for your lot comes first, and its figure is the one to follow.
Check a blend against its IFRA limits and list its allergens in the fragrance and allergen calculator.
How essential oils behave in soap, and how much to use: Scenting soap.
Identity and labelling
Boswellia Carterii Oil
- Botanical name
- Boswellia carterii
- CAS
- 89957-98-2, 8050-07-5
- EC
- 289-620-2, 232-474-1
The EU does not name this oil itself as an allergen to label, but some of its constituents may be: the fragrance allergen tool works them out for a recipe.
What it is and how it behaves in soap
Frankincense oil is steam-distilled from olibanum, the gum resin tapped from Boswellia trees (CBI). Somalia and Ethiopia are by far the biggest producers of the resins, and in Somalia the tree sold as Boswellia carterii, which many botanists treat as Boswellia sacra, is tapped in two seasons a year (FAO). It smells fresh, resinous and faintly lemony, like incense before it burns.
Cable counts frankincense among the base notes that help lighter scents last and uses it at 0.6 to 1.2 % of the oils, often with orange; Grosso calls it a good binder for other fragrances. The IFRA figure on this page is the ceiling.
Wild frankincense is under strain. Somali trees are over-tapped without their year of rest (CBI), and Boswellia papyrifera, now the main source of the resin, is expected to yield half as much within 20 years (Bongers and colleagues). Fakes are common: all 21 "pure carterii" oils in one test were adulterated (Ojha and colleagues).
Recipes that use it
Sources
- CosIng, the cosmetic ingredient database: BOSWELLIA CARTERII OIL, European Commission
- The European market potential for essential oils, CBI, Netherlands Ministry of Foreign Affairs (2026). Steam distillation of the gum resin; trees in Somalia over-tapped without a sufficient one-year resting period
- J. J. W. Coppen, Flavours and fragrances of plant origin (Non-Wood Forest Products 1), Food and Agriculture Organization of the United Nations (1995). Somalia and Ethiopia by far the biggest producers; Boswellia sacra (syn. B. carteri) tapped in two periods a year in Somalia
- Kelly Cable, The Natural Soap Making Book for Beginners, Althea Press (2017). Frankincense as a base note, at 0.6 to 1.2 % of the oils
- Alicia Grosso, The Everything Soapmaking Book, 3rd edition, Adams Media (2013). Frankincense a good binder for other fragrances
- Bongers and colleagues, Frankincense in peril, Nature Sustainability 2, Springer Nature (2019). Boswellia papyrifera, now the main source of frankincense: over 75 % of populations lack young trees, and production is projected to halve in 20 years
- Ojha and colleagues, Comparison of volatile constituents present in commercial and lab-distilled frankincense (Boswellia carteri) essential oils, Plants 11, MDPI (2022). All 21 commercial oils sold as pure Boswellia carteri were adulterated or contaminated