Qu'est-ce que le surgras dans les savons faits par saponification à froid ?

What is superfat in cold process soaps?


Superfat is a key concept in cold process soap making, and it is one of the elements that directly influences the quality and final properties of the soap. This term refers to the excess oil that does not saponify during the chemical process, meaning that some of the oil remains in its original form, without being transformed into soap. Here is a more detailed explanation of what superfat is and how it impacts artisanal soaps.

1. The saponification process

Cold saponification is a chemical reaction that occurs when fats (oils or butters) are mixed with an alkaline solution, such as caustic soda (sodium hydroxide) and water. This reaction transforms the oils into soap and glycerin.

However, some of the added oils do not turn into soap, they remain "free" in the formula, without reacting with the soda. This creates what is called a superfatted soap . The higher the percentage of superfat, the more unsaponified oils the soap contains, which makes the soap nourishing and emollient for the skin.

2. The benefits of superfatting

  • Hydration and nutrition : Unsaponified oils retain their natural properties and directly nourish the skin. For example, a superfatted soap with coconut oil can soften and moisturize dry skin.

  • Softness : Superfatted soaps are softer and less aggressive for the skin, because some of the oils act as a natural moisturizer.

  • Personalization : Depending on the type of oil used for the superfat, the soap can offer specific benefits. For example, olive oil has regenerative properties, while shea butter is extremely nourishing and protective.

3. How to calculate the excess fat

In handmade soap making, superfat is expressed as a percentage. For example, a soap with 5% superfat means that 5% of the oils will not react with the caustic soda. Superfat is generally between 3% and 15% , depending on the skin type the soap is designed for and the desired properties.

  • Dry skin : Soaps with a high superfatting content (10%-15%) are ideal for dry skin, as they provide more intense hydration.

  • Oily or combination skin : A lower superfatting content (3%-6%) is recommended, as it avoids making the soap too oily.

4. Impact of superfatting on the longevity of the soap

One of the downsides of a superfatted soap is that it can be softer and wear out more quickly. It is therefore important to store it properly, letting it dry between uses, preferably in a soap dish that allows good drainage.

Superfat is an element that distinguishes quality artisanal soaps, especially in cold saponification. It is a way to personalize soaps to make them more nourishing, moisturizing and soft, and each soap is unique, bringing natural benefits to the skin. Finding the right balance of superfat is essential to obtain a soap adapted to your skin type and your specific needs.

In my experience, when making coconut oil soaps , I often opt for a 15% superfat, as I like my soaps to be extremely nourishing, especially for dry or sensitive skin.

This process makes each soap I create not only a care product, but also a gesture of softness for the skin.

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