Cold Soap Making at Home
07-05-2025
17:17
Cold soap production with olive oil is a soap consumption culture that is both friendly to your skin and the environment.
What is Cold Soap?
One of the most basic chemical reactions, the "saponification reaction" is the process of salt formation after the reaction of acid and base.
The reaction can occur even with natural/non-chemical materials; when mixed with oil and wood ash mixed with water, a natural caustic source, a soapy slurry will spontaneously form.
The acid source is oil (vegetable or animal) and the base source is caustic (sodium hydroxide, NaOH).
There is more than one "fatty acid molecule" in olive oil, with the most "oleic acid".
The main process difference between the cold process soap making method and the hot process soap making method is related to the temperature and time management during which the chemical process called saponification takes place.
In both methods, oils and lye react, but the details of the production steps and the properties of the resulting soap are different.
In the cold method, the process is carried out at room temperature. The saponification reaction that continues in the slurry poured into the mold continues to occur at a slow rate in the mold.
After solidification, the resulting soap enters a “maturation” process for 4-6 weeks, during which time the soap is not yet ready to be used.
After a waiting period of 4–6 weeks, the soap begins to dry (the water in the slurry evaporates), its pH drops, and it reaches a balanced usable state.
The degradation rate of nutritional phytochemicals (such as polyphenols, vitamin E, squalene) found in natural virgin olive oil is much lower compared to the hot method.
Additionally, if essential oils (lavender, bay leaf, rosemary, etc.) are added for essence, the oils will integrate into the soap without spoiling since the process is carried out at low temperatures.
Advantages of the cold method:
Nutritious oils and essential oils retain their properties because they are not exposed to heat.
In the cold method, beneficial components such as polyphenols, vitamin E, and squalene in olive oil are preserved and the potential for these molecules to pass through to the skin is preserved.
It is the ideal method for production without perfume or with natural essences.
Essential oils (lavender, bay leaf, rosemary, etc.) are processed at lower temperatures in the cold method, so they integrate into the soap without being spoiled.
More decorative and aesthetic soaps can be produced.
Essential oils (lavender, bay leaf, rosemary, etc.) are processed at lower temperatures in the cold method, so they integrate into the soap without being spoiled.
Hemp oil is one of the alternatives that can be used to benefit from its moisturizing and antioxidant properties.
If transparency is not desired, color and texture control is more precise.More decorative and aesthetic soaps can be produced.
Disadvantages of the cold method:
A long waiting period is required.
The saponification process is beyond control (progresses naturally).
How to Make Cold Soap?
Security Precautions
Before you start construction, you should make sure that you have taken safety precautions.
Caustic (NaOH, sodium hydroxide) is an irritating chemical that can damage your skin. You can protect your skin by wearing latex gloves, your eyes with goggles and your face with a face mask.
It is important to wear long-sleeved clothing and carry out the process in a well-ventilated environment.
During the combination of caustic and water, irritating volatile gases are released, you should perform this step under an aspirator or in the open air.
You should not reuse kitchen utensils such as blenders, wooden spoons, cups and containers for any other purpose.
Things to Know Before Making Olive Oil Solid Soap
The weights specified in the ingredient list are critical to the successful application of the olive oil solid soap recipe.
Since each oil has its own saponification coefficient, grammages are very important to make correct calculations, and exact application of the measurements is essential for the correct completion of the saponification process.
The saponification coefficient of olive oil is 0.1345-0.136 g NaOH/g oil. These values are calculated according to the average molecular weight of more than one fatty acid - since there is not a single fatty acid in olive oil. If you want to make a very sensitive production, you need to have the olive oil you use analyzed and learn the oil ratios it contains.
Sample Caustic Amount Calculation for 1000 g of olive oil:
1. If the NaOH saponification value is taken as **0.135 g/g**:
Required NaOH = 1000 g x 0.135 = 135 g NaOHHow to Make Cold Soap?
Security Precautions
Before you start construction, you should make sure that you have taken safety precautions.
Caustic (NaOH, sodium hydroxide) is an irritating chemical that can damage your skin. You can protect your skin by wearing latex gloves, your eyes with goggles and your face with a face mask.
It is important to wear long-sleeved clothing and carry out the process in a well-ventilated environment.
During the combination of caustic and water, irritating volatile gases are released, you should perform this step under an aspirator or in the open air.
You should not reuse kitchen utensils such as blenders, wooden spoons, cups and containers for any other purpose.
Things to Know Before Making Olive Oil Solid Soap
The weights specified in the ingredient list are critical to the successful application of the olive oil solid soap recipe.
Since each oil has its own saponification coefficient, grammages are very important to make correct calculations, and exact application of the measurements is essential for the correct completion of the saponification process.
The saponification coefficient of olive oil is 0.1345-0.136 g NaOH/g oil. These values are calculated according to the average molecular weight of more than one fatty acid - since there is not a single fatty acid in olive oil. If you want to make a very sensitive production, you need to have the olive oil you use analyzed and learn the oil ratios it contains.
Sample Caustic Amount Calculation for 1000 g of olive oil:
1. If the NaOH saponification value is taken as **0.135 g/g**:
2. If you want to apply 5% superfat:
Required NaOH = 135g x 0.95 = 128.25g NaOH
The term superfat is used to describe the action of using less caustic than is required in the saponification reaction to prevent the oil from completely saponifying, thus leaving free (unsaponified) oil in the final product. The aim is to prevent the risk of excess caustic, reduce the drying effect of the soap and obtain a product that leaves a softer feel.
During the production phase, the unsaponifiable fat ratio (superfat) can be kept around 5%. A superfat ratio of 10% and above reduces the cleansing character of the soap, leaves an excessively oily feeling and shortens its shelf life. A superfat ratio below 3% causes the soap to harden and gain a drying feature.
The soap water ratio should also be adjusted well, incorrect calculation will cause mold.
The gel phase should be carefully observed in the first 48 hours after molding.
For initial production runs, it is best to start by testing the formula described below and making small quantities of soap.
Equipment:
- Precision scales.
- Hand blender or a wooden stick/spoon.
- Gloves, safety glasses, mask for safety.
- Mold (Silicone soap mold, a disposable plastic or a container with wax paper inside).
Ingredients for approximately 1 kg of soap:
- 700g of olive oil.
- 90 g sodium hydroxide (5% superfat; 5% less caustic).
- 230 g of drinking water (the standard ratio is approximately 1/3 of oil).
- A container to mix the lye and water (except for Aluminium).
If desired;
10 g of essential oil or dried aromatic herbs for essence purposes.
Clay, honey and yogurt.
Step 1: Preparing the Caustic and Water Mixture
First, add 160 grams of drinking water into a bowl.
Step 1: Preparing the Caustic and Water Mixture
First, add 160 grams of drinking water into a bowl.
Then slowly add 65 grams of caustic soda to the water.
Be careful when doing this; caustic should be added to water, not the other way around, water should never be added to caustic.
During this step, the water heats up and an irritating volatile gas is released, so it is important to do this step outdoors or in a well-ventilated area.
After adding caustic, the mixture is left to stand until it reaches room temperature.
Step 2: Mixing Oil and Caustic
Immerse a blender into the olive oil. Start adding the room temperature caustic and water mixture that you prepared beforehand to the olive oil little by little, while mixing it with the blender at the same time.
Complete this process (slow addition and intermittent mixing) gradually, in several additions.
Continue mixing the mixture with the blender until you obtain a homogeneous slurry.
Turn off the blender occasionally and check the homogeneity of the mixture. At this stage, the color of the mixture will slowly begin to darken.
The blender should be kept constantly in the mixture to prevent air bubbles from appearing while the blender is running.
Be careful when doing this; caustic should be added to water, not the other way around, water should never be added to caustic.
During this step, the water heats up and an irritating volatile gas is released, so it is important to do this step outdoors or in a well-ventilated area.
After adding caustic, the mixture is left to stand until it reaches room temperature.
Step 2: Mixing Oil and Caustic
Immerse a blender into the olive oil. Start adding the room temperature caustic and water mixture that you prepared beforehand to the olive oil little by little, while mixing it with the blender at the same time.
Complete this process (slow addition and intermittent mixing) gradually, in several additions.
Continue mixing the mixture with the blender until you obtain a homogeneous slurry.
Turn off the blender occasionally and check the homogeneity of the mixture. At this stage, the color of the mixture will slowly begin to darken.
The blender should be kept constantly in the mixture to prevent air bubbles from appearing while the blender is running.
When the mixing step is finished, the mixture should turn into a slurry with the consistency of boza and pudding.
The soap mixture is now ready to be poured into the mold.
Essential oil and aromatic herbs are added at this stage.
Additions such as clay, honey and yoghurt should be made after gaining experience, especially clay is a preferred option due to its antibacterial effect.
Step 3: Casting
As molds, you can use disposable plastic containers, silicone soap containers, or a wooden mold with baking paper inside.
Step 4: Waiting in the Mold
Leave the soap in the mold at room temperature for at least 24 hours, up to 48 hours can be allowed.
Step 5: Waiting for Drying
Your oil has turned into a cleaning product, but you must remove the soap from the mold and let it dry.
You can also perform the drying process by cutting the soap into slices.
In this final step, it is important for the quality of the product that your soaps dry thoroughly.
After making olive oil soap using the cold method, we cannot use the soap immediately; it may take up to 1-2 months for the soap to dry and be ready for use, depending on the air temperatures.
If you live in a place with average humidity, you may need to wait 1 month; if you live in a place with high humidity, you may need to wait 2 months.
You can check whether the soaps you have left to dry are dry by turning them from time to time.
It is normal for soap made only from olive oil to leave a slippery feeling.
Compiled by: Uğur Saraçoğlu, Physician, Olive and Olive Oil Producer (ugisaracoglu@yahoo.com.tr)