Why ingredients are used, where they appear and the questions we ask when selecting products.
Why Do Similar Products Contain Different Ingredients?
Every soap, liquid cleanser, lotion or household product is the result of hundreds of decisions.
Some ingredients provide cleansing. Others improve stability, preserve the product, enhance fragrance, contribute colour or help it perform more effectively in hard water.
As specialists in traditional soaps and household products, we spend a great deal of time reviewing ingredient lists. Not because we believe every ingredient is either good or bad, but because every ingredient should have a purpose.
When assessing a product, we rarely ask whether an ingredient sounds natural or synthetic. Instead, we ask:
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Why has it been used?
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What does it contribute to the finished product?
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Is it necessary?
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Are there suitable alternatives?
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How does it affect performance, safety and environmental impact?
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Is the manufacturer transparent about its use?
Over the years, certain ingredients have appeared time and again. Some are essential to traditional soap making. Others reflect modern advances in formulation, biodegradability or product stability. A few generate questions simply because their names sound unfamiliar.
This guide explains some of the ingredients we encounter most often, why they are used and how we think about them when selecting products for French Soaps UK.
Sodium Hydroxide
Why It Is Used
Soap cannot be made without an alkali. Sodium Hydroxide is the ingredient that transforms oils into soap during the process of saponification.
What It Is
Also known as lye or caustic soda, Sodium Hydroxide is an essential part of traditional soap making.
How It Appears on Labels
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Sodium Hydroxide
Our Perspective
One of the most common misconceptions is that Sodium Hydroxide remains present in the finished soap.
In a properly made soap, the Sodium Hydroxide has already reacted with the oils and has been consumed during the soap-making process. Its appearance on an ingredient list is often a reflection of transparent labelling and traditional manufacturing methods rather than an indication that caustic soda remains in the bar.
Palm Oil
Why It Is Used
Palm oil contributes hardness, durability and a rich, stable lather.
What It Is
A vegetable oil obtained from the fruit of the oil palm tree.
How It Appears on Labels
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Palm Oil
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Palm Kernel Oil
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Sodium Palmate
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Sodium Palm Kernelate
Our Perspective
Palm oil remains one of the most debated ingredients in soap making. It also has a dedicated guide within The French Soap Library. When assessing palm-derived ingredients, we consider sourcing, stewardship, performance and the practical realities of alternative oils rather than making assumptions based solely on the ingredient name.
Fragrance Allergens
Why They Are Listed
Certain fragrance compounds must be declared individually to help consumers with known sensitivities identify them.
What They Are
Naturally occurring aromatic compounds found in essential oils, fragrance compositions and botanical extracts.
How They Appear on Labels
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Limonene
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Linalool
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Citral
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Geraniol
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Citronellol
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Coumarin
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Eugenol
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Farnesol
Our Perspective
Many fragrance allergens occur naturally in ingredients that customers actively seek out, including citrus oils, lavender, rose and verbena. Their presence does not indicate that a product is unsafe; rather, it reflects modern transparency requirements.
Preservatives
Why They Are Used
To help prevent the growth of bacteria, mould and yeast.
What They Are
Ingredients that help maintain product safety and stability throughout their intended lifespan.
How They Appear on Labels
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Sodium Benzoate
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Potassium Sorbate
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Benzyl Alcohol
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Dehydroacetic Acid
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Phenoxyethanol
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Ethylhexylglycerin
Our Perspective
Not every product requires preservation.
Traditional soap bars contain very little free water and often require little or no additional preservation. Liquid soaps, lotions and creams are different. Once water is present, preservation becomes an important part of responsible formulation.
A well-chosen preservative is often a sign of a product designed to remain safe and stable throughout its use.
Sodium Gluconate
Why It Is Used
To improve performance in hard water and support formulation stability.
What It Is
A chelating agent typically produced through the fermentation of plant-derived sugars.
How It Appears on Labels
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Sodium Gluconate
Our Perspective
Although the name sounds technical, Sodium Gluconate is increasingly used because it performs an important role while offering excellent biodegradability.
Tetrasodium Glutamate Diacetate (GLDA)
Why It Is Used
To help products perform consistently in hard water and improve formulation stability.
What It Is
A modern chelating agent produced from glutamic acid, an amino acid obtained through the fermentation of plant-derived sugars.
How It Appears on Labels
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Tetrasodium Glutamate Diacetate
Our Perspective
This ingredient is a useful reminder that a complicated name does not necessarily indicate a harsh ingredient. It is increasingly used as an alternative to older chelating agents because it combines performance with improved biodegradability.
EDTA
Why It Is Used
To bind naturally occurring minerals that can interfere with product performance.
What It Is
A highly effective chelating agent used in a wide range of personal care and household products.
How It Appears on Labels
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Disodium EDTA
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Tetrasodium EDTA
Our Perspective
EDTA remains widely used because it works extremely well. However, many manufacturers have gradually moved towards alternatives such as Sodium Gluconate and GLDA that offer improved biodegradability.
Sodium Sulfate
Why It Is Used
As a processing aid and formulation ingredient in certain products.
What It Is
A naturally occurring mineral salt.
How It Appears on Labels
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Sodium Sulfate
Our Perspective
Despite the similar name, Sodium Sulfate should not be confused with cleansing sulphates such as Sodium Lauryl Sulfate (SLS). The two ingredients perform entirely different functions.
Sulphates
Why They Are Used
To provide effective cleansing and abundant foam.
What They Are
A family of cleansing agents commonly used in shampoos, body washes and household products.
How They Appear on Labels
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Sodium Lauryl Sulfate (SLS)
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Sodium Laureth Sulfate (SLES)
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Ammonium Lauryl Sulfate
Our Perspective
Sulphates remain widely used and effective cleansing agents. However, some people find them drying or irritating, particularly on sensitive skin. Traditional soaps achieve cleansing through a different mechanism and do not necessarily rely on sulphate-based detergents.
Colourants
Why They Are Used
To provide colour, visual consistency and product identification.
What They Are
Colourants may be derived from minerals, plants, insects or synthetic sources.
How They Appear on Labels
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CI 77491, 77492, 77499 (Iron Oxides)
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CI 77007 (Ultramarines)
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CI 77891 (Titanium Dioxide)
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CI 75810 (Chlorophyll)
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CI 75120 (Annatto)
Our Perspective
A Colour Index (CI) number is simply a standardised identification system and does not indicate whether a colourant is natural or synthetic. Understanding a colourant's source and purpose is usually more informative than judging it by its name.
PEGs and Parabens
Why They Are Used
PEGs are typically used to improve stability and texture. Parabens are used to preserve products from microbial contamination.
What They Are
Two ingredient groups that have generated significant discussion within the cosmetic industry over the past two decades.
How They Appear on Labels
PEGs:
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PEG-7 Glyceryl Cocoate
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PEG-40 Hydrogenated Castor Oil
Parabens:
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Methylparaben
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Ethylparaben
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Propylparaben
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Butylparaben
Our Perspective
These ingredients appear only occasionally within our range. When assessing them, we apply the same questions we ask of every ingredient: why is it there, what purpose does it serve and are there suitable alternatives?
Why Biodegradability Matters
An ingredient's journey does not end when it goes down the drain.
Increasingly, formulators consider not only how an ingredient performs in a product, but also how it behaves once it enters the wider environment. This has encouraged the adoption of ingredients that combine performance with improved biodegradability and reduced environmental persistence.
As with any ingredient, context matters. An ingredient's environmental impact cannot be determined simply by whether its name sounds natural or synthetic.
The Question We Always Return To
When assessing any ingredient, we rarely ask whether it is good or bad, instead, we ask a simpler question:
What purpose does it serve?
If an ingredient improves performance, safety, stability or environmental outcomes, it may have a valuable role to play. If it serves no clear purpose, we start asking more questions.
Understanding ingredients is not about avoiding long names. It is about understanding why they are there in the first place.