Soap making oils can be used in the saponification process as base oils, while also serving as carrier oils. When used as base oils, they are combined with lye and water to undergo saponification, the chemical reaction that turns oils into soap. This process determines how the soap performs, including hardness, how the bar feels during use, lather, and overall durability.
The same oils can also be used as carrier oils, meaning they are used in their original form rather than being transformed through saponification. Carrier oils are non-volatile, which makes them useful when working with fragrance oils and essential oils that evaporate quickly. When a scent oil is blended with a carrier oil, the carrier helps slow the rate of evaporation. This supports scent retention and helps fragrance and essential oils distribute evenly throughout a formula.
The Role of Carrier Oils in Scent Blending and Bar Feel
Carrier oils can also be used to dilute highly concentrated fragrances and essential oils, which helps reduce the risk of skin irritation and prevents the finished product from being overpowering. Because carrier oils are generally more cost-effective than fragrance oils and essential oils, they can help lower production costs by allowing concentrated scents to be used at low percentages within a carrier oil base.
In soap making and body care, oils are valued for their emollient qualities. They leave skin feeling soft and smooth. In handmade soap, these qualities come from the fatty acids present in the oils that remain after saponification. Those fatty acids influence how the finished bar interacts with the skin during and after washing, affecting slip, after-feel, and overall comfort. By adjusting the blend of oils in a recipe, makers can control how a bar feels without changing the structure of the soap itself.
Common Carrier Oils and Their Role in Formulation:
- Jojoba Oil: Closely resembles skin’s natural sebum, making it a popular choice for facial products and leave-on formulations where skin feel is a priority
- Sweet Almond Oil: Lightweight and emollient, often used to soften skin and improve glide in soaps, lotions, and body care products
- Apricot Kernel Oil: Similar in feel to sweet almond oil, with a slightly richer profile that works well in products designed for dry or sensitive skin
- Sunflower Seed Oil: Mild and versatile, commonly chosen for gentle soap formulas and body care products intended for frequent use
- Rice Bran Oil: Provides balanced conditioning without feeling heavy, making it useful in both soap recipes and leave-on formulations
- Olive Oil: Known for its conditioning properties and often used to support a softer, more moisturizing feel in soap and skincare products
Because these soap-making oils can serve multiple roles, selecting the right one depends on whether it will be transformed during saponification or used as a carrier in its original state. Understanding how each oil functions in a formula helps makers create consistent, skin-friendly products across soap and body care projects.
Can the same oil be used as both a base oil and a carrier oil?
Yes. Many soap-making oils can serve different roles depending on how they are used. When combined with lye and water, an oil acts as a base oil and goes through saponification to become soap. When used separately and left unchanged, the same oil can function as a carrier oil in formulations such as soap additives or body care products.
What does volatile mean in soap making?
A volatile ingredient tends to evaporate easily. Fragrance oils and essential oils can lose intensity over time for this reason. Mixing them with a carrier oil helps slow that evaporation and keep the scent more stable within a formula.
What does emollient mean in soap making?
In soap making, emollient refers to how oils influence the way skin feels after washing. Emollient oils help leave skin feeling soft and smooth by affecting the surface feel of the skin once the soap is rinsed away.