Natural soaps or handmade soaps usually are made in a more eco-friendly way. It’s primarily because it does not contain any detergent. We all know that detergents are primarily known to create a lot of lather and natural soaps do not have them as an ingredient. So, that brings us to the question, “How does natural soap create lather?” Well, first off, the amount of lather created by a natural soap is way less as compared to its commercial alternative. But hey! natural soaps are way better for your skin than their commercial alternatives.

In this post, we’ll be going in-depth on how the process takes place and what is the cause of lather formation. Let’s start with the basics.

What Are Bubbles?

Ever made bubbles through a straw into our glass of milk? It’s very easy and if there’s enough space, soon your glass would get filled with loads of bubbles. But when you try to do the same with water, it would not be as effective. The bubbles did not foam up and they pop very quickly. This is simply because water bubbles are less stable because the surface tension (we’ll be covering this) pulls the water molecules back together.

Difference? The milk contains milk proteins and fats. The proteins and fats here, form a film in the bubble which makes it stronger and more stable. Also, milk has a lower surface tension than water. Whenever surface tension is reduced, bubbles are formed more stably.

How are Soap Bubbles formed?

There are many different kinds of “soap” products but they have one major thing in common, they all can make bubbles.

When you get a bunch of tiny soap bubbles together, it is called lather. You may choose a bar of natural soap or synthetic detergent soaps or shampoo, or dishwashing liquid, the process of bubble making is primarily the same.

To understand the process of bubble-production of soap, we need to learn a little bit about chemistry. So, here it comes!

Property of Water: Surface Tension

If you could see molecules of water, you would notice that each water molecule is attracted (bonded) to its neighbors.

how does natural soaps create lather

Each molecule of water has two hydrogen atoms and one oxygen atom, that’s why the chemical composition is H2O. The two hydrogen atoms of one molecule are attracted to the oxygen atoms of other nearby molecules. This attraction is called “hydrogen bonding.”

Within the body of the water, away from the surface, every molecule is involved in a pushing and pulling tug of war with its neighbors on all sides.

But on the surface of the water, the molecules behave differently.

Since there are no water molecules above the surface, the surface molecules are pulled back into the liquid by the water molecules below them. As the molecules on the surface of the pool are pulled tightly together, they form a “skin” like a thin layer of plastic wrap called surface tension.

how soaps make lather

Surface tension is the result of cohesion which is defined as the “sticking-together” of particles. It is the surface-tension-cohesion attraction of particles to one another at the surface of a liquid.

While all liquids have some surface tension, the stronger the intermolecular forces, the greater the cohesion offered. Water has strong intermolecular forces — they are the hydrogen bonds described above.

So, whenever you hit the water, you have to break the surface tension of the water to enter (that’s why the first hit is hard). When you jump off into a pool you break through a small amount of the water with your hands or feet. But your belly having a large surface area, needs a larger amount of surface “skin” to breakthrough it.

Surface Tension & Soap

Soap is a natural surfactant, which is short for “surface active agent.” As their name might suggest, surfactants reduce the surface tension of water.

Water will normally hold to itself if place droplets on a wax paper because each water molecule is surrounded by and attracted to other water molecules. The property of surface tension causes water to bead-up on surfaces, like wax paper. In a nutshell, for the water to cover your skin and wet its surface —there’s a need for surfactants.

The Explanation

Soap molecules have two ends to them, the end that likes to stick to water is called the hydrophilic end (water-loving) and the end that repels water is called the hydrophobic end (water-hating).

How Does Soap Create Lather

The soap molecule acts as a connecting bridge. The hydrophilic end of the molecule attaches to water and its hydrophobic end gets attached to the dirt or oil molecule.

When you rinse the soap off of your skin, the water-loving (hydrophilic) end of the soap molecule gets washed away with the water and takes the hydrophobic (water-fearing) end with the dirt and oil along with it. End result? your skin is cleaned.

So, How Does Natural Soap Create Lather?

When soap mixes with water it tends to create thin sheets in which a thin layer of water molecules is sandwiched between two layers of soap molecules.

The soap molecules trap water in a thin layer, creating a film.

Source: itsokaytobesmart.com

You may see how the layer of (blue and yellow) water molecules is surrounded on either side by soap molecules with the hydrophilic end (red) covering towards the water, and the hydrophobic tail covering away from the water.

When you run a bar soap over your wet skin, or wash clothes or scrub to create friction. This friction introduces tiny air bubbles onto the surface of the wet soap. The water-repelling(hydrophobic) end does not like the wet, watery soap and wants to leave, so it gets attached to the nearest air bubble.

Soon the air bubbles are covered in the hydrophobic (water-repelling) ends of the soap molecules. This results in creating a thin film that encloses a tiny bit of air in it.

What do we call that? Answer: a soap bubble!

If we could cut a bubble in half we would see something like the following picture.

The bubble is filled with air and the surface of the soap bubble is a thin layer of water sandwiched between two layers of soap molecules, one on the inside and the other on the outside of the bubble. These layers are strong enough to hold the water and work together by trapping the air inside.

The interaction between the bubbles pushes the molecules of water away from each other, which results in relieving surface tension.

So a soap bubble is just air wrapped in a film made from soap and water. The air bubbles are now trapped between the molecules, and when a lot of trapped air bubbles covered in soap molecules are what we call it as the soap lather.

Finally!

“If your soap does not contain any foam boosters, how does soap create lather?”

At the beginning of this post, we mentioned that if you try to make bubbles using plain water, it does not work very well. This is because the cohesion and thus the surface tension, the forces holding the molecules together, of water is too high.

The secret to making good bubbles is to decrease the surface tension of the water in solution. Adding natural soap to water changes the surface tension of water and allows it with stable bubbles, and thus, to help form lather.

Almost all cleaning products are based on some sort of surfactant. Surfactants not only reduce the surface tension of the water but the way they are constructed (hydrophilic end and hydrophobic end) makes them compatible with both water and oils.

This property is what makes them good for cleansing. When surfactants lower the surface tension of water, they make the water molecules more slippery, so they are less likely to stick to themselves and more likely to interact with oil and grease.

Natural soap needs no synthetic additives to create a lather or to clean because natural soap is a natural surfactant. So it not only makes great bubbles and lather, but it also helps clean oily dirt from your skin — naturally!

But there are also many synthetic surfactants. Synthetic detergents are all surfactants and the word detergent is just a synonym for the word surfactant

Commercial “soaps” (which are not soaps at all) use detergents that clean and act as foam boosters or foaming agents to provide the copious amounts of lather that consumers love. The so-called used chemicals are very inexpensive and serve no purpose other than to provide thick, foamy lather which is not needed to clean your body at all.

So create some natural lather with a natural bar of soap and save your skin and our planet too! It the reason why, we, at Avrell, take this mission seriously!

You may also like,

What is a REAL Soap & How is it Made?

10 Benefits of Using Organic Soaps for Skin

How Does Soap Work

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