Although following the recipe it is possible to make homemade Castile soap with other fats, in this publication we will see how to make olive oil soap.
As with other products, depending on the type of olive oil used, soap quality varies. In the same way that the use of evoo in kitchen is the most indicated, in the case of Castile soap, we will also get better results.
Obviously we don’t need to use the best extra virgin olive oil on the market to make a quality soap. But we can take advantage of the usual offers that are made when the date of preferential oil consumptionis approaching.
Whenever possible, we should use at least one virgin olive oil. It should be remembered that virgin olive oil is a completely natural product, extracted directly from olives using only mechanical means. The presence of antioxidants, polyphenols, oleocanthal and other components, provide positive properties to soaps that are made with virgin olive oil On the other hand, by making homemade soap with used olive oil, we cannot take advantage of some of these interesting properties.
In addition, oil is a cheap product and the price difference between making homemade Castile soap with extra virgin olive oil and olive oil is small. If we value the time we will invest in making soap, we will realize that it is absurd to skimp on the raw materials used.
Why is soap made with olive oil and caustic soda?
Olive oil is made up of different fatty acids (oleic, linoleic, palmitic, stearic…). For its part, caustic soda (NAOH) is a strong base.
When an acid is combined with a base, a chemical reaction results that results in salt + water and is usually exothermic (gives off heat).
When making Castile bars soap, the most common is to use caustic soda, although if we want it is also possible to make liquid Castile soap or detergents using caustic potash (KOH).
If we want to make soap without using caustic soda, caustic potash is an alternative, although it is even more aggressive than soda, so we have to be especially careful during handling. In addition, the final result is different.
The reaction that occurs when you gather oil with a strong base is called saponification
During the saponification process, the fatty acids combine the base dissolved in water, resulting in soap and glycerin.
Trioleina more bland → Sodium Oleate and Glycerin
C57H104O6 +3 NaOH → 3 C18H33O2Na + C3H8O3
Note: Soap is called sodium and potassium salts resulting from the saponification of fatty acids.
Warning: When handling caustic soda or potassium hydroxide, caution must be taken and avoid direct contact with skin, eyes, mucous membranes, clothing…
The saponification tables indicate the amount of caustic soda and potassium hydroxide needed to completely convert the fat into soap.
This table tells us the precise amount, if we add more, there will be traces of soda left unreacted in the soap.
On the contrary, if we take less, free fat will remain in the soap. An excess of free soda can make aggressive soap for the skin.
|Type of oil||Grams NaOH / kg oil||Grams KOH / kg oil|
|Avocado||134 g||188 g|
|Apricot||139 g||195 g|
|Cotton||138 g||194 g|
|Sweet almonds||137 g||193 g|
|Hazelnut||139 g||195 g|
|Peanut||137 g||192 g|
|Pumpkin||138 g||193 g|
|Coco||191 g||268 g|
|Wheat||132 g||185 g|
|Sunflower||135 g||189 g|
|Linen||135 g||190 g|
|Corn||137 g||192 g|
|Olive||135 g||190 g|
|Palma||142 g||199 g|
|Palmiste||157 g||220 g|
|Grape Nugget||129 g||181 g|
|Ricino||129 g||180 g|
|Sesame||134 g||188 g|
|Soy||136 g||191 g|
To convert 1 kg of olive oil into soap, we need at least 135 grams of soda.
Knowing that the density of olive oil is 0.916 kg / liter. We can calculate that we need 124 grams per liter of olive oil. However, if we are going to remove the mixture manually, adding more soda will help us make the reaction faster.
Preparations for making soda soap with olive oil
Before making the soda soap, we will need to prepare the protective equipment and have the necessary ingredients to make olive soap.
Materials and protective measures for make homemade soap
To make homemade soap safely, we must take into account the handling measures indicated by the caustic soda supplier.
The most common is to use waterproof gloves and glasses protection. Although it is also advisable to protect the nose and mouth. To do this, we can use a mask like the ones used in front of the olive allergy.
- Waterproof gloves
- Safety glasses
- Plastic container of about 9 liters
- Stick or tool to remove
- Soap molds or other containers to pour the mixture
Recipes of homemade Castile soap or Marseille soap
The homemade soap, is known by several names (Castile or Marseille) depending on the raw material used during its elaboration.
- Castile soap: only olive oil is used as vegetable fat. A genuine Castile soap, you have to use as a fat, 100% olive oil for its elaboration. It is known as Castile Soap, because the crown of Castile was the main producer and exported soap to other countries in Europe and America. For centuries it has been a soap valued for its excellent quality, today, although its consumption has declined in favor of other products, it is still a very popular handmade soap.
- Marseille or Lizard Soap: You can use vegetable oils other than olive oil for your production. In Spain, it is popularly known as Lagarto soap, because it was marketed under this brand.
Ingredients for making Castile soap with olive oil
These ingredients are what my grandmother used to make homemade Castile soap and are the measures traditionally used in Spain.
- 3 liters of water
- 3 liters of olive oil
- 500 grams of soda
Although 372 grams of caustic soda would be enough to complete the reaction. When using 500 grams of soda, less effort is needed to make the soap, since the reaction is carried out faster.
In some publications they recommend even adding 10% less soda so that free oil is left. The result is a softer soap, however, the shelf life of the soap will be shorter, as it could get dirty. If you use less soda than indicated in the recipe, I recommend using mechanical means to remove the mixture.
My mother is the soap she uses, since bath gels have produced allergic reactions.
Steps to follow to make olive oil soap
The next steps are what I do to make soap with olive oil.
- First of all, we put on security equipment.
- We add 3 liters of water to the plastic container.
- We put the 500 grams of soda caustic to the water.
- Remove until the soda is dissolved in the water. During this process, toxic vapors come out that it is better not to inhale, so it is recommended to make the mixture outdoors.
- During this process, the soda and water react forming bleach and the mixture gets quite hot. Therefore, before continuing, we need to wait 5-10 minutes for the mixture to temper.
- We carefully add the 3 liters of olive oil while stirring the mixture.
- Let’s stir in the same direction the mixture until the reaction is complete. Once the reaction is complete, the color of the mixture is bleached and smells like soap. When done manually, it must be stirring for approximately 1 hour. 💪 Come on, a free gym day. 😉 If we use whipping tools, the process is faster and more comfortable.
- Optional: add dyes or flavorings and stir well.
- We carefully pour the mixture into a mold or container.
- We wait 7 to 14 days for the mixture to solidify to unmold or cut the soap. It is important not to wait in excess, since the soap hardens over time and becomes brittle. Depending on the weather conditions and the thickness of the tablets it will take more or less to dry.
- We let a month go by before using the soap. During this time, the soda remains will continue to react until the saponification is complete.
In the following video we can see Eugenio Arenas clearly explain the process about how to make olive oil soap.
Natural dyes and aromas
On the other hand, we can flavor the soda soap using flavorings such as natural essential oils. In this way, aromatic soaps such as lavender soap are maked.
Make homemade soap with used olive oil
Traditionally, fats from fried foods have been used to make homemade soap. However, the results when making soap with used oliveoil, are not as good. This is due to the presence of impurities that produce unpleasant aromas in the soap.
Imagine washing with soap and smelling fish fry, chips, piglet…
As we have said, the quality of the soap will depend on the raw material used. Although, the steps to follow to make homemade soap with used oil are the same.
Personally, I would not recommend using this soap for personal hygiene. However, it can be useful for other applications and is a good way to give used cooking oil.
If we are going to use used oil to make soap, it is important that we filter it at least twice and let the oil settle to completely remove the remains of fritters.
You already know how to make soap with olive oil, but surely other publications may interest you:
We have translated the information on our website from Spanish to English. Note that some words may have seen their meaning altered during their translation.