What Are Carrier Oils?
Carrier oils are plant-derived oils extracted from seeds, nuts, or kernels. They serve as the base of countless skincare products and are a fundamental ingredient in cold process soap making. Unlike essential oils, carrier oils are not volatile — they don't evaporate and are safe to apply directly to the skin (though patch testing is always recommended).
Each carrier oil has a unique fatty acid profile, which determines its skin feel, comedogenic rating, shelf life, and suitability for different skin types. Understanding these properties helps you choose the right oil for your recipe or routine.
Key Properties to Look for in a Carrier Oil
- Fatty acid composition — the balance of oleic, linoleic, lauric, and other acids affects skin absorption and barrier support
- Comedogenic rating — a scale of 0–5 indicating how likely an oil is to clog pores (0 = won't clog, 5 = highly comedogenic)
- Shelf life — oils high in linoleic acid have shorter shelf lives and are more prone to going rancid
- SAP value — relevant for soap making; determines how much lye is needed to saponify the oil
The Most Popular Carrier Oils at a Glance
| Oil | Key Benefit | Best For | Comedogenic Rating |
|---|---|---|---|
| Olive Oil | Deeply moisturizing, oleic-rich | Dry, mature skin; classic soap base | 2 |
| Coconut Oil | Hard bar, high lather, cleansing | Soap making (max 30%), oily skin | 4 |
| Castor Oil | Humectant, boosts lather | Soap making (5–10%), dry skin | 1 |
| Jojoba Oil | Mimics sebum, balancing | All skin types, acne-prone | 2 |
| Sweet Almond Oil | Lightweight, softening | Sensitive and combination skin | 2 |
| Rosehip Seed Oil | Vitamin A & C, regenerating | Mature, scarred, hyperpigmented skin | 1 |
| Avocado Oil | Rich, nourishing, oleic-heavy | Very dry or mature skin | 3 |
| Argan Oil | Balancing, antioxidant-rich | All skin types, hair care | 0 |
Deep Dive: Key Carrier Oils
Olive Oil
The backbone of traditional Castile soap, olive oil is rich in oleic acid (~70%), which makes it deeply moisturizing and skin-softening. It produces a soap with a creamy, conditioning lather — though bars made with high percentages of olive oil take longer to cure and can be soft straight out of the mold. In skincare, it's excellent for dry and mature skin but may be too heavy for oily or acne-prone types.
Coconut Oil
Coconut oil is a powerhouse in soap making, contributing hardness, a fluffy lather, and excellent cleansing. It's high in lauric acid, which is responsible for its antimicrobial properties. However, it can be drying when used in excess, so it's best kept below 30% in soap recipes. For direct skincare use, it's best for those with dry skin, as its comedogenic rating of 4 makes it risky for acne-prone individuals.
Jojoba Oil
Technically a liquid wax rather than a true oil, jojoba is incredibly stable and closely resembles the skin's natural sebum. It's non-comedogenic, suitable for all skin types, and has a very long shelf life. While it's not commonly used in large quantities in soap making (it resists saponification), it shines as a leave-on skincare ingredient and is excellent in serums, lotions, and hair care.
Rosehip Seed Oil
Cold-pressed from the seeds of rose hips, this oil is packed with essential fatty acids and naturally occurring vitamin A (trans-retinoic acid). It's one of the most popular natural oils for addressing hyperpigmentation, fine lines, and acne scarring. Due to its high linoleic acid content, it has a shorter shelf life — store it in the refrigerator and use within 6 months of opening.
Storing Carrier Oils Properly
To extend shelf life and preserve the quality of your oils:
- Store in dark glass bottles away from heat and direct sunlight
- Add vitamin E (tocopherol) at 0.5–1% as a natural antioxidant to delay rancidity
- Refrigerate highly unsaturated oils like rosehip, hemp seed, and evening primrose
- Label bottles with the purchase date and use-by reference
Choosing the Right Oil for Your Purpose
When building a soap recipe, think about the balance of fatty acids — you want a mix of hard and soft oils for a balanced bar. For skincare, match the oil's properties to your skin concerns: oleic-rich oils for moisture, linoleic-rich oils for acne and brightening, and stable oils like argan or jojoba for daily use. The more you understand each oil, the more intentionally you can formulate.