How surfactants work in cleaning

When I first started making my own cleaning products, I kept coming across the word "surfactant" a lot. 

It sounds complicated, but a surfactant is actually a cleaning function and has one very important job: helping water lift and remove dirt, grease and oils. Without a surfactant, water alone struggles to clean oily messes.

There are various types of surfactants and there are many products types. For example, Sodium Laureth Sulfate (SLES) is a surfactant.

Soap is one of the oldest and most common surfactants, which is why you'll find it in so many natural cleaning recipes.

How does it work

To explain how they work, I like to think of surfactants as tiny tadpoles.

The tadpole's head loves water (hydrophilic), while its tail hates water (hydrophobic).

When a surfactant is mixed with water, the water-hating tails go looking for grease, oil and dirt to attach themselves to.

As more surfactant molecules gather, they surround the dirt and trap it in a tiny bundle called a micelle.

Why rinsing is so important

Once the dirt is trapped inside the micelle, it can be carried away by water.

When you rinse, the water-loving heads follow the flow of water, pulling the trapped dirt away from the surface.

This is why rinsing is such an important part of cleaning. The dirt needs somewhere to go.

Take a look at my beautiful Canva diagram below. The ring of little "tadpoles" surrounding the dirt is called a micelle.

Dealing with hard water

Traditional soap has one weakness: hard water.

The surfactant can react with minerals such as calcium and magnesium found in hard water. When this happens, the soap becomes less effective and can leave residue behind.

The harder the water, the harder soap has to work.

Water softeners help

This is where ingredients like Washing Soda, Borax and Bicarb Soda come in.

These ingredients help soften the water by tying up some of the minerals that cause hardness. This allows the soap to focus on lifting dirt rather than reacting with the minerals in the water.

Why this matters

Understanding surfactants helps explain why soap is such an important ingredient in cleaning.

The soap isn't just sitting in the recipe because someone decided it should be there. It's the ingredient doing the work of lifting dirt from the surface so it can be washed away.

In the Under Your Sink toolkit, our surfactants are simple, traditional soaps such as Castile Soap and Coconut Soap Flakes.