If you are getting started with soap making, you have probably heard the term saponification a few times. While it is a long word and can sound a little confusing, it isn’t as bad as it may sound.
We tried to break down exactly what saponification is and how it is used in soap making in the post below. You’ll be a pro soaper in no time with this knowledge!
So, What is Saponification?
Saponification is a chemical reaction between a fatty acid and a strong base that results in the formation of soap. Often times, the strong base is sodium hydroxide (NaOH) or potassium hydroxide (KOH). The ensuing reaction involves the cleavage of the ester bond in the fatty acid. This results in the formation of the salt of the fatty acid (soap) and glycerol.
Saponification is a commonly used process in the soap-making industry. In this case, natural fats or oils, such as coconut oil or olive oil, are treated with a strong alkali. The chemical reaction will produce soap with cleansing properties.
The process of saponification can also occur naturally, as in the case of soapberry fruit. Soapberry fruit contains saponins that can lather and clean when mixed with water.
Saponification is also used in the production of biodiesel, where vegetable oils or animal fats are reacted with an alcohol and a catalyst to produce fatty acid methyl esters (FAMEs) and glycerol. This process is also known as transesterification, and it is similar to saponification in that it involves the cleavage of ester bonds in fats or oils.
What is Saponification in Soap Making?
Saponification is the chemical reaction that occurs when a fat or oil is mixed with an alkali, like sodium hydroxide or potassium hydroxide. When mixed together, a chemical reaction occurs to produce soap. The process involves breaking down the triglycerides in the fat or oil into their component fatty acid chains. They then react with the alkali to form soap molecules and glycerol.
During the saponification process, the fatty acid chains in the fat or oil are transformed into the salt of the corresponding fatty acid. This is what gives soap its cleansing properties and will naturally break up oil when used to clean. The glycerol, which is a byproduct of the reaction, can be recovered and used for other purposes.
In soap making, the saponification process is typically carried out in one of two ways. One is by mixing the fat or oil with the alkali in a process called “cold process” without heat. The other is by heating the mixture in a process called “hot process.”
Once the saponification is complete, the soap is usually cured for several weeks to allow excess water to evaporate. During the curing process, the soap will harden and become milder.
What Kind of Fat is Used in Soap?
Traditionally, soap is made from fats and oils, which are typically derived from animals or plants. The most common fats used in soap making are:
- Tallow (derived from beef)
- Lard (derived from pork)
- Coconut oil
- Shea butter
- Cocoa butter
- Palm oil
- Olive oil
- Sunflower oil
These fats contain a mixture of fatty acids, including stearic acid, oleic acid, and lauric acid, which play an important role in determining the properties of the soap.
For example, lauric acid produces a soap that is hard and lathers well. Oleic acid produces a soap that is softer and has good conditioning properties.
Today, many soap makers use vegetable oils and butters, such as olive oil, soybean oil, sunflower oil, shea butter, and cocoa butter, which are more sustainable and environmentally friendly than animal fats.
What Kind of Alkali is Used in Soap Making?
An alkali is a chemical compound that has a pH greater than 7 and can neutralize an acid. Alkalis are also called bases and are commonly used in various industries, including soap making, cleaning, and agriculture.
The alkali used in soap making is typically sodium hydroxide (NaOH), also known as lye or caustic soda. Another alkali is potassium hydroxide (KOH), also known as caustic potash.
The type of alkali used depends on the type of soap being made. Sodium hydroxide is used for making solid bar soap, while potassium hydroxide is used for making liquid soap.
When an alkali, such as sodium hydroxide or potassium hydroxide, is mixed with fats or oils, a chemical reaction called saponification occurs, which produces soap and glycerin. The alkali acts as a catalyst, breaking down the triglycerides in the fat or oil into glycerol and fatty acids, which then combine with the alkali to form soap molecules.
What is Lye?
Lye is a term that is often used interchangeably with sodium hydroxide, which is a highly caustic and alkaline chemical compound that is commonly used in the production of soap, as well as in other industrial processes.
Sodium hydroxide, also known as caustic soda or lye, is a strong base that has the chemical formula NaOH. It is highly corrosive and can cause severe burns if it comes into contact with skin or eyes. Therefore, it must be handled with care and caution when used in soap making or other applications.
In soap making, lye is used to saponify fats and oils, which is the process of turning them into soap. The lye reacts with the fats and oils to form soap molecules and glycerin. The resulting soap is then rinsed and cured to remove any excess lye and to allow it to harden and mature.
Is Lye Dangerous?
Lye, also known as sodium hydroxide or caustic soda, is a highly caustic and alkaline chemical compound that can be hazardous if not handled properly. It is corrosive and can cause severe burns if it comes into contact with skin, eyes, or mucous membranes. Ingestion of lye can also be extremely dangerous.
However, when used correctly and with proper safety precautions, lye can be used safely in soap making and other industrial processes. It is important to follow specific safety guidelines when handling lye, including wearing appropriate protective equipment such as gloves, eye protection, and long sleeves, as well as using a well-ventilated area to avoid inhaling any fumes.
Additionally, when making soap, it is essential to accurately measure and mix the lye and other ingredients according to the recipe. This will help to ensure that the final product is safe and effective for use.
Overall, while lye can be dangerous if not handled properly, it can be used safely and effectively with proper safety measures and procedures.
How to Calculate the Saponification Rate for Soap Making
The calculation of saponification is used to determine the amount of alkali (sodium hydroxide or potassium hydroxide) needed to saponify a certain amount of fat or oil. The amount of alkali required for saponification is known as the saponification value or number.
Here is the general formula for calculating saponification:
Saponification value = (mass of alkali used x 56.1) / mass of fat or oil used
where 56.1 is the molecular weight of potassium hydroxide (KOH) or sodium hydroxide (NaOH).
To calculate saponification, you will need to know the mass of the fat or oil you are using, the mass of the alkali (KOH or NaOH) you added, and the molecular weight of the alkali. Once you have these values, you can use the formula above to calculate the saponification value.
It’s worth noting that different types of fats and oils have different saponification values due to their different molecular structures, so you’ll need to look up the saponification value for the specific fat or oil you’re using.
Here are a few soap saponification calculators that make it easy to determine the exact ratios you need.
What is Superfatting in Soap Making?
Superfatting is the process of adding extra fats or oils to soap recipes to increase their moisturizing properties. When making soap, a specific amount of lye is mixed with fats or oils, which causes a chemical reaction known as saponification.
This process converts the fats or oils into soap, but sometimes the lye doesn’t completely react with all the fats or oils, leaving some of them in their original form. This unreacted fat or oil is what we refer to as superfatting.
Superfatting can be done intentionally by adding extra fats or oils at the end of the soap making process, or it can happen naturally if the soap recipe has an excess of fats or oils.
The level of superfatting in a soap recipe can affect the properties of the finished soap, such as its cleansing ability and its moisturizing properties.
A higher level of superfatting can make a soap more moisturizing, but it can also make it softer and reduce its lather. On the other hand, a lower level of superfatting can result in a harder soap with a more cleansing effect, but it can also be more drying to the skin.
Therefore, the level of superfatting should be carefully chosen depending on the desired properties of the finished soap.
Simple Cold Process Soap Recipe
Here’s a simple recipe for making a basic cold process soap at home.
Ingredients:
- 500g vegetable oil (such as olive oil, coconut oil, or sunflower oil)
- 63g lye (sodium hydroxide)
- 150ml water
- Essential oils (optional)
Equipment:
- Heat-resistant container (such as Pyrex glass)
- Digital scale
- Stick blender
- Soap mold
- Protective gear (gloves, goggles, long-sleeved shirt, pants, and closed-toe shoes)
Instructions:
- Weigh out the vegetable oil into a heat-resistant container.
- In a separate container, carefully weigh out the lye.
- Add the lye to the water and stir until it has completely dissolved.
- Allow the lye mixture to cool to around 100-110°F (38-43°C).
- Slowly pour the lye mixture into the vegetable oil, stirring constantly with a stick blender until it reaches a trace (when the mixture thickens and leaves a visible trail when drizzled).
- Add any essential oils or fragrance oils if desired.
- Pour the mixture into a soap mold and tap gently to remove any air bubbles.
- Cover the mold with a towel or plastic wrap and let it sit undisturbed for 24-48 hours to allow the soap to set and harden.
- After 24-48 hours, remove the soap from the mold and cut it into bars.
- Allow the soap to cure for 4-6 weeks before using or gifting.
Note: Always follow safety precautions when working with lye, and handle it carefully and with protective gear.
Good luck creating your homemade soap!
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