When you think of traditional bar soap, a few famous examples tend to come to mind: Aleppo soap from Syria, Castile soap from Spain and Savon de Marseille from France.
What connects these soapmaking traditions is olive oil.
Traditional Aleppo soap is made from olive oil together with laurel oil, while olive oil played an important role in the development of Marseille soap and became the defining ingredient of traditional Castile soap. In other words, long before coconut oil and shea butter that we use in our soap today, olive oil had already established itself as one of the most important raw materials in soapmaking.12
There are several reasons for this. The obvious one is accessibility in the region but more importantly, its particular fatty-acid composition produces a soap with distinctive characteristic that are particularly healthy for your skin.
In this article, we look at why olive oil is used in soap, its history, how the oil is produced, the different grades available and what it actually contributes to a finished bar.
What is olive oil?
Olive oil is the oil extracted from the fruit of the olive tree, Olea europaea.
Unlike many vegetable oils that are extracted primarily from seeds, olive oil comes from the fleshy fruit itself.
Most of the oil consists of triglycerides: molecules made from glycerol attached to three fatty acids. It is the composition of those fatty acids that makes different oils behave differently when turned into soap.
Olive oil is particularly rich in oleic acid, a monounsaturated fatty acid. According to International Olive Council standards, oleic acid typically represents approximately 55–83% of the fatty acids in olive oil.3
It also contains smaller amounts of:
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palmitic acid
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linoleic acid
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stearic acid
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linolenic acid
These are equally important as oleic acid to the bar of soap and higher amounts of these are added to the bar of soap through our other ingredients. For example linoleic acid is higher in shea butter and stearic acid is higher in coconut oil.
These proportions vary depending on factors such as olive variety, climate, ripeness and growing conditions.3 Hence it is important for us to always know the state of the olive oil that we use in our soap bar. For example, the olive oil that we use always has a minimum of 56% of oleic acid but more often it is closer to 85%. For us, this fatty-acid profile is very important because the oil itself changes inside the finished bar:
It becomes natural soap molecules.
How is olive oil produced?
The process begins with harvesting olives from the tree. (surprise!!)
At the mill, leaves and other material are removed and the olives are washed. The whole fruit is then crushed into a paste.Traditionally this was done using large stone mills. Modern olive mills generally use mechanical crushers.
The paste is then mixed in a process called malaxation. This allows small droplets of oil to combine into larger ones so that they can be separated more easily.
Modern mills typically use centrifugation to separate the oil from the water and solid parts of the olive. The remaining solid material is known as olive pomace.4
For virgin olive oils, the International Olive Council specifies that extraction must rely only on mechanical or physical processes. Treatments such as chemical refining are not permitted for oils classified as virgin.5
After extraction, the oil can be filtered, stored and classified according to its chemical and sensory characteristics.
Olive oil has been used in soap for centuries
Olive oil and soapmaking have a particularly long relationship around the Mediterranean and Middle East.
One of the clearest surviving examples is Aleppo ghar soap from Syria.
UNESCO added the craftsmanship of Aleppo ghar soap to its Representative List of the Intangible Cultural Heritage of Humanity in 2024. The traditional process combines locally produced olive oil with laurel oil and lye. The soap is cooked, poured across the floor of the soap factory, cut into individual bars and then left to dry for several months.1
Olive-oil soap also became an important product elsewhere around the Mediterranean.
In Spain, soaps made predominantly or entirely from olive oil became associated with the region of Castile, giving rise to what we today call Castile soap.
Marseille developed another major soapmaking tradition.
Historical records from the City of Marseille show soap production in the region dating back to at least the 14th century. Olive oil became increasingly important in Mediterranean soapmaking, although Marseille producers later began using other vegetable oils such as rapeseed, linseed, coconut and palm oils as supply, cost and industrial production changed.2
So while it would be slightly too simple to say that all traditional Marseille soap is purely olive-oil soap, olive oil played an important part in the development of the tradition.
What happens to olive oil when you make soap?
This is probably the most important thing to understand when discussing the benefits of olive oil in soap.
The olive oil does not only get mixed into the bar, it undergoes a chemical reaction called saponification. In this process, fats or oils react with an alkali such as sodium hydroxide.
Olive oil + sodium hydroxide → soap + glycerin
In more precise terms, the triglycerides in olive oil are broken apart. Their fatty acids react with sodium to form fatty-acid salts - the actual soap molecules - while glycerin is produced alongside them.
Because olive oil contains so much oleic acid, an olive oil based soap contains a large proportion of oleate soap molecules, commonly represented in our ingredient lists as Sodium Olivate. This distinction matters.
The properties of raw olive oil cannot automatically be used to describe the properties of olive-oil soap. One is primarily triglyceride oil; the other contains saponified fatty acids.
Why is olive oil so popular in soap?
There is no single perfect oil for soapmaking. Different oils contribute different characteristics to a natural soap bar.
Coconut oil, for example, contains comparatively high levels of fatty acids such as lauric acid. These produce highly soluble soap molecules that generate plenty of lather and strong cleansing action.
Olive oil on the other hand, behaves differently. Its high concentration of oleic acid creates soap with comparatively different lather, cleansing and physical characteristics. This is the very reason why we spent two years perfecting our recipes to get the best of each oil we use in our soap bars. We wanted the hardness and lather from the coconut oil but also the moisturizing properties from the olive oil.
A mild cleansing profile
One of the main reasons olive oil has remained popular in soapmaking is the relatively gentle character traditionally associated with olive oil based soaps.
This does not mean every olive oil soap is automatically gentle. Our opinion is that a pure olive oil soap is not optimal for the perfect shower experience if you want a well-lathering and moisturizing soap bar. In our early tests, we used a proportionally high olive oil base but quickly realized the bars lacked the foam that we wanted to achieve.
However, it is clear that the olive oil in our soap bars do provide a milder-feeling cleansing bar, which is one of the properties we are looking for in our soap bars.
A dense, creamy lather
Another feature of olive oil in soap is that it generally produces a restrained, creamy and fine foam.
This is one of the reasons olive oil is often blended with oils such as coconut or castor oil. Because without them, you get a very fine foam but no bubbles and you will also get a relatively soft bar.
Olive oil can form the foundation of the bar, while other oils are used to change how quickly the soap lathers, the size of the bubbles and how the foam feels on the skin.
It contributes to the structure of the bar
A freshly made high olive oil soap can initially be relatively soft. The high concentration of oleic acid means the saponification process is slower and thus the soap may need longer time for curing.
Aleppo soap, for example, is traditionally stored for six to nine months after production.1
In a formulation containing several different oils, these properties can be balanced so the bar reaches its desired hardness much sooner.
Glycerin is naturally created from olive oil
Another important property of traditional soapmaking is the production of glycerin.
Glycerin is not something naturally contained inside the original bottle of olive oil. Instead, it is released from the triglyceride molecules during the saponification process.
Glycerin is a humectant, meaning that it attracts and binds water. In our handmade and soaps, that glycerin remains in the finished product, which is one of the reason why it is so good for your skin.
This benefit therefore comes from the soapmaking process itself rather than being unique to olive oil, but olive oil provides the triglycerides from which both the soap molecules and glycerin are produced.
Is olive oil good for your skin?
Olive oil contains several compounds that are interesting from a skincare perspective, including oleic acid, squalene and phenolic compounds. These substances have antioxidant and emollient properties and are studied for their use in cosmetic formulations.9
However, as with all things in skincare, the frequency and amount of olive oil you put on your skin matters. If you want to apply olive oil directly on your skin, try it and see how it feels. Many of our customers mention benefits from olive oil directly applied on their skin although it may not be the most common natural oil that is applied directly on skin.
When it comes to soap, olive oil is very good to use on your skin for the reasons mentioned earlier: the glycerin, the mild bar and the remaining oil that is left from “overfatting” the soap.
Different types of olive oil used in soapmaking
Not every bottle labelled olive oil is the same.
The International Olive Council divides olive oil into several different categories depending on how it is produced and its chemical and sensory characteristics.5
Extra virgin olive oil
Extra virgin olive oil is the highest recognised grade of virgin olive oil.
It is obtained exclusively through mechanical or other physical processes and must meet strict chemical and sensory requirements. Among these requirements, its free acidity must not exceed 0.8 grams per 100 grams, expressed as oleic acid.5 For food, its flavour, aroma and minor compounds are extremely important.
For soapmaking, however, many of these differences become less relevant because the triglycerides are going to undergo saponification. Using extra virgin olive oil therefore does not automatically produce a better bar of soap.
Virgin olive oil
Virgin olive oil is also mechanically extracted but has different permitted chemical and sensory characteristics from extra virgin olive oil.
Its fundamental triglyceride and fatty-acid composition nevertheless makes it perfectly capable of being used as a soapmaking oil.5
Refined olive oil
Olive oils that do not meet the requirements for virgin oils can be refined.
Refining removes undesirable odours, flavours, pigments and other compounds while largely retaining the triglyceride structure of the oil.5
For a soapmaker, this can be useful depending on how much control of the resulting bar the soapmaker wants. When the objective is ultimately to convert the triglycerides into soap, a neutral and consistent refined oil can sometimes be more practical than an expensive culinary extra virgin oil which you would rather want to have on your salad.
Lampante olive oil
Lampante olive oil is a grade of virgin olive oil that does not meet the requirements for direct consumption.
The International Olive Council describes it as oil intended either for refining or for technical use.5
Historically, lower-grade olive oils have often been useful raw materials for soapmaking rather than being wasted.
Research comparing non-edible olive oil with higher-quality virgin olive oil has even found that the resulting Castile soaps have more or less similar physical and chemical characteristics.8
Of course, this does not mean that any poor quality oil should simply be used in cosmetics. For our olive oil, we still require appropriate specifications, quality controls and safety assessments to ensure the olive oil will work as intended for our bars of soap.
Olive pomace oil
After virgin olive oil has been mechanically extracted, some oil remains in the solid olive residue known as pomace.
That remaining oil can be extracted and refined to create olive pomace oil.
Its production is therefore different from virgin olive oil, although its fatty-acid composition can still potentially be used in soapmaking.
Is extra virgin olive oil better for soap?
Not necessarily. This is one of the places where cooking and soapmaking should not be mixed up.
When buying olive oil to eat, you might choose extra virgin olive oil because of its flavour, aroma and naturally occurring minor compounds. When we make soap, we take a completely different objective.
We are primarily interested in things such as:
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fatty-acid composition (i.e how much oleic acid does it contain?)
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consistency between batches
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oxidation
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colour
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odour
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traceability
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purity
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how the oil behaves during saponification (we continuously run experiments on our oils)
The majority of the oil is going to be chemically transformed into soap molecules.
That means paying a premium for an exceptional culinary oil does not necessarily translate into great soap bar. The quality of the finished bar depends much more on how the entire recipe has been designed.
Why we use olive oil in soap
Olive oil has survived centuries of soapmaking for a reason.
Its high oleic acid content gives soapmakers like us a very different building block from other oils such as coconut, cocoa butter or castor oil.
Used on its own, it can create the classic character of Castile soap. Used as part of a more complex formulation, like the recipe for our soap bars, it provides a mild feeling foundation that other oils can build upon - adding more lather, hardness and natural glycerin.
That’s why we use olive oil in our soap bars and will continue to do so.
Sources
[1] UNESCO - Craftsmanship of Aleppo Ghar Soap. UNESCO Representative List of the Intangible Cultural Heritage of Humanity, inscribed 2024. Traditional Aleppo production using olive oil and laurel oil, including its long drying period.
[2] Ville de Marseille - “Un cube mythique, 100 % naturel et 100 % marseillais.” History of soapmaking in Marseille, including the increasing use of olive oil and later introduction of other vegetable oils.
[3] International Olive Council - Trade standards / fatty-acid composition of olive oil. IOC specifications place oleic acid at approximately 55–83% of total fatty acids in olive oil.
[4] European Commission, Directorate-General for Agriculture and Rural Development - Production of Virgin Olive Oils. Overview of harvesting, washing, crushing, extraction, centrifugation and olive-pomace production.
[5] International Olive Council - Olive Oils: Designations and Definitions. Definitions of extra virgin, virgin, lampante, refined and olive-pomace oils.
[8] Girgis AY - “Production of high quality castile soap from high rancid olive oil.” Grasas y Aceites, 2003;54(3):226–233. Comparison of Castile soap produced from non-edible and virgin olive oils.
[9] Wołosik et al./review literature - research on olive-derived compounds and squalene in topical applications. Olive oil contains minor compounds including squalene and phenolic substances of interest to cosmetic science.