Laundry detergent, washing-up liquid, soap, floor cleaner… We use cleaning products every day without necessarily knowing how they work. Yet behind these everyday tasks lies a real science: detergency.
Why is water alone not always enough to remove dirt? What role do surfactants play in our household products?
At Terre de Bougies, we invite you to explore how cleaning works, so you can better understand the products you use and the ingredients they contain. Having explored the world of home fragrance diffusers and scented wax melts, let’s turn to another way of fragrancing everyday life: household products.
Complete guides to making your own household products and soaps
What is detergency?
Detergency is the action of removing dirt from a surface or a textile, in particular through the use of cleaning agents. It is at work in many everyday tasks: washing your laundry, degreasing your dishes or cleaning the surfaces in your home.
Why do we talk about “detergents” at Terre de Bougies?
At Terre de Bougies, we chose the term “detergents” to bring together our range of products for everyday cleaning and household care.
This range covers several applications: laundry detergent for textiles, washing-up liquid, floor and surface cleaners, and liquid soaps for hand hygiene.
Our aim? To help you discover this world and personalise your everyday products with ready-formulated neutral bases and specially adapted fragrances.
Please note: liquid soap for the skin is part of our “detergents” range, but it falls under cosmetics regulations, unlike products intended for cleaning surfaces and textiles.
How does cleaning work?
Why is water alone not always enough?
You have probably noticed it already: rinsing a greasy plate under the tap is not always enough to get it clean.
The explanation is simple: water and fats do not mix easily. Water can remove some soluble dirt, such as salt or sugar, but it struggles to lift the oily residues that cling to surfaces.
Water also has a property called surface tension. Among other things, this explains why a drop of water tends to keep a rounded shape rather than spreading out completely.
This is where cleaning agents come in, and surfactants in particular. By lowering this surface tension and making it easier for water and fats to interact, they help water wet surfaces more effectively and help remove dirt when you rinse.
Why is foam not a sign of effectiveness?
We often tend to associate plenty of foam with effective cleaning. Yet a product that foams a lot does not necessarily clean better than a low-foaming one.
Foam forms when air is trapped in a liquid, in particular through the action of certain surfactants. How much foam there is depends on how the product is formulated, but foam alone cannot tell you how well it cleans.
Take two examples:
- A washing-up liquid for washing by hand can produce a generous lather, which is pleasant to use and helps spread the product.
- A machine laundry detergent generally needs to keep its foam under control to work properly with the movement of the drum.
In both cases, effectiveness depends above all on the formulation and on how well it suits its intended use.
Foam is therefore a characteristic of the product, not a guarantee of cleanliness.
Surfactants: the molecules that make cleaning possible
Surfactants sometimes have a poor image, yet they play an essential role in many formulations. Beyond their ability to help keep mixtures stable, they have several properties that make them useful in a wide range of fields, such as cosmetics, pharmaceuticals and the food industry. Depending on their function, surfactants can be:
- Foaming agents: they promote the formation of foam.
- Detergents: they make it easier to remove dirt and impurities.
- Solubilisers: they make it possible to incorporate certain ingredients that are poorly soluble or insoluble in a given medium.
- Emulsifiers: they help two liquids that do not naturally mix, such as oil and vinegar, to blend and stay stable.
- Wetting agents: they improve a liquid’s ability to spread over a solid surface, such as a product applied to the skin.
How does a surfactant work?
What makes a surfactant special is its structure. Each molecule has two parts with different properties:
- A hydrophilic part, which has an affinity for water.
- A hydrophobic part, which avoids contact with water and generally has an affinity for fats.
Thanks to this dual nature, surfactants can position themselves between water and grease, making it easier to lift the grease off the surface being cleaned.
When they are present in sufficient quantities, some surfactants can also organise themselves into small clusters called micelles. Their hydrophobic part turns inwards, while their hydrophilic part stays in contact with the water.
These structures can help keep fats dispersed in the water, so that they are easier to wash away when rinsing.
It is thanks to these properties, among other things, that a washing-up liquid can help lift grease off a plate, or that a laundry detergent can remove certain types of dirt from textile fibres.
Good to know: not all surfactants are the same. Depending on their chemical structure, some are particularly valued for their cleaning properties, others for their foaming, emulsifying or softening properties. That is why the choice of surfactant depends on the function required in the finished product.
Are surfactants bad for your health or the environment?
Surfactants sometimes have a bad reputation. Often associated with industrial chemicals, they can be seen as harsh on the skin or harmful to the environment.
Yet not all surfactants have the same properties or the same impact.
Some are derived from plant-based raw materials, such as coconut, palm or olive oil. Others can be obtained from fossil resources. But their origin alone does not determine how safe they are or what impact they have on the environment.
Several criteria need to be taken into account:
- The nature of the surfactant: some molecules can be more irritating than others, depending in particular on their concentration and the conditions of use.
- Biodegradability: this refers to the ability of a substance to be broken down by micro-organisms under defined conditions.
- The overall formulation: the properties of a finished product depend on all its ingredients, how they are combined and their concentration.
- The conditions of use: the dosage, how often the product is used and the quantities released into wastewater also influence its environmental impact.
In Europe, surfactants used in detergents are subject to regulatory requirements, particularly regarding biodegradability.
So there are two shortcuts to avoid: assuming that a surfactant is necessarily bad because it comes from chemistry, or that it is automatically risk-free because it comes from a natural raw material.
What matters is not simply where an ingredient comes from, but its properties, how it is used and how it behaves in the finished product and in the environment.
From theory to practice: make your own household products
Now that you know the principles of detergency and the role of surfactants, why not put them into practice? Discover our guide to detergents, with recipes to learn how to make and personalise your own household products.
