What is Soap? Looking into the Ingredients and Their Roles

Soap making is similar to baking a cake, just don't lick the spoon at the end

Quick Summary / TL;DR

• Definition: Soap is the result of a chemical reaction called saponification between fats (oils) and an alkali (lye).

• Process: Fats + Lye Water = Soap + Glycerin.

• How it cleans: Soap molecules have a hydrophilic (water-loving) head and a hydrophobic (oil-loving) tail that trap dirt in micelles to be washed away.

Have you ever wondered what soap actually is? At our Berlin-based soap manufactory, we create natural soaps using the traditional cold-process method. Every bar is handcrafted in Berlin, blending the science of saponification with high-quality botanical ingredients.

Saponification is a chemical reaction occurring between oils or butters and alkaline water. During this process, glycerin is the key ingredient produced, along with soap molecules.

fats + alkali = soap + glycerin

Let's go over each of these substances together.

1. Fats (oils & butters)

They are greasy or oily substances that help in the absorption of vitamins and support healthy skin in humans, plants, and animals. Additionally, they serve as the main method for energy storage in the body. In plants, these substances usually gather in seeds (such as sunflower, sesame...) or in the flesh of fruits (like olive, avocado...).

Their chemical structure consists of 3 branches connected to a backbone, known as triglycerides. This molecule is quite large and elongated, contributing to the oil's relatively high viscosity. The more solid the oil, the longer the branches.

higher viscosity, from light oils to soft and hard butters

I invite you to get information about oils on a more detailed level here (3min read).

Spoiler alert: this might get a bit technical, and it could bring back memories of challenging high school chemistry classes... However, truly grasping a subject often requires diving deeper. I promise you'll discover something intriguing, not just about cosmetics but also regarding the food industry (trans-fats).

2. Lye water

When an alkali is mixed with water, it creates a high pH solution called lye water. This solution is highly reactive and powerful enough to decompose fat molecules into soap and glycerin. Lye is the sole substance capable of performing this reaction, making it essential for soap production.

The alkali employed in soap manufacturing is either sodium hydroxide (NaOH) or potassium hydroxide (KOH):

• NaOH is utilized to create a solid soap bar

• KOH is utilized to produce liquid soap

• Combining both results in soap with a creamy texture, perfect for shaving cream.

Saponification reaction: oils and lye water are fully transformed into soaps and glycerin

3. Glycerin

This substance is generated as a byproduct of the saponification reaction and is a natural humectant that supports skin hydration:

• Its hydrating and moisturizing qualities help the skin feel softer and more comfortable after washing.

• Helps provide a gentle cleanse that is less likely to leave the skin feeling tight or overly dry.

• By supporting skin hydration, it can help the skin cope better with everyday environmental irritation.

• Helps maintain the skin’s natural barrier function during cleansing by reducing moisture loss compared with more drying soaps.

At babassu soaps, sustainability is at the core of what we do. By choosing the cold-process method, we ensure the natural glycerin remains in the bar, resulting in a product that is not only better for your skin but also 100% biodegradable and a much better eco-score.

This substance is valuable and is occasionally extracted from the soap to be sold at a higher price than it would within the soap. This isn't beneficial for your skin, as the gap left by the missing glycerin is often filled with less expensive chemical alternatives. Naturally derived glycerin remains in natural soaps, making up about 9% of the final product. The remainder consists of soap molecules (over 85%) and water. As the water gradually evaporates, it leaves the soaps.

4. How is soap cleaning?

Let's revisit our depiction of a soap molecule:

• It contains a lengthy carbon chain that draws in fats, microbes, and dirt,

• while the opposite end is negatively charged and attracts water molecules.

Dirt is distinct because it does not dissolve in water. When a soap molecule encounters dirt, fats, or microbes, its tail is drawn to them and will "penetrate" the dirt.

The other part, which is drawn to water, seeks to remain as distant from the dirt as possible, yet it is linked to the tail. Picture an array of soap molecules attacking the dirt from every angle until they create a sphere, with the dirt at the core. The dirt is now easily rinsed away because it is water soluble.

It's formed what's known as a micelle.

Since bacteria and viruses possess lipid (fat) membranes, the effect on them is similar. Piercing this barrier breaks it down, exposing the microbe's interior to water, which effectively kills it.

2D and 3D representation of a micelle. The dirt is covered of soap molecules which make it soluble in water.

Corona update

The term "anti-microbial soap" is redundant, similar to "vegan water" or "burning fire," because all soaps naturally have anti-microbial properties.. Don't always fall for stunning marketing claims. Which soap is best against viruses? The answer also well explained here.

FAQ

Is handcrafted soap more sustainable than industrial soap?

Yes. Handcrafted soap has a much better eco-score because it uses a low-energy cold-process method and retains 100% of the natural glycerin. This makes the final product 100% biodegradable and eliminates the need for synthetic detergents that can harm aquatic life.

Why is glycerin important in natural soap?

During the saponification process, glycerin is naturally created. While industrial brands often remove it to sell as a separate byproduct, we keep it in our bars. Glycerin is a humectant, meaning it draws moisture into your skin, preventing the dryness often associated with mass-produced soaps.

Does your soap contain lye?

While lye (sodium hydroxide) is used to trigger the chemical reaction, no lye remains in the finished bar. It is completely transformed during saponification into soap and glycerin, making the final product gentle and safe for the skin.