Sulphates in the Personal Care industry - myth busting

But first, let’s learn a little more about sulphates and how they are typically used in cosmetic formulations…

What are sulphates and what are they used for?

Sulphates are a class of anionic surfactants that typically act as detergents in cosmetic formulations such as facial cleansers, shampoos, and body washes. The most common of this type of ingredient used in personal care applications are sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES). Due to chemical modification, SLES is a milder alternative to SLS, but is still perceived as a harsh surfactant in the eyes of the consumer thanks to the link to sulphates. Their primary function is to deliver effective cleansing to the hair and skin which, combined with their great foaming performance, makes them popular ingredients for use in cleansing formulations.

Why do sulphates have a bad reputation?

Sulphates have been used safely in the personal care industry for many years, but have developed a negative consumer perception for a number of reasons. Their job is to cleanse the hair and skin, but they can sometimes work too effectively, removing not only soils, but also stripping the hair and skin of its natural oils. This can be perceived as too harsh for certain hair types or can lead to irritation in sensitive skin.

However, it is important to acknowledge that sulphate-based ingredients provide a lot of benefits in cosmetic formulations. As I mentioned earlier, they are effective cleansers and have excellent foaming properties, as well as offering some viscosity-building characteristics. They are cost-effective ingredients that are generally light in colour and low in odour, making them very easy to formulate into a wide range of products. So, when we take out the sulphates, there isn’t a direct replacement. Instead, a combination of different chemistries are  often needed to achieve the same effects as those offered by sulphates. This can present a tricky challenge for cosmetic formulators!

Now that we know a little more about the background of sulphates and how they are used in the personal care industry, let’s now take a look at some common myths…

Myth 1 – Sulphate-based cleansers are harsh and can dry out the hair and skin

There is growing sentiment that sulphate-based cleansers can be harsh, tending to leave hair dry and brittle, causing irritation and drying out the skin. This is often attributed to the removal of the natural oils present on the hair and skin surface. It’s true that sulphates are very efficient cleansers, so they will remove natural oils as well as dirt and soil – after all that is their job! This is why conditioning of the hair and moisturisation of the skin is essential after cleansing to replenish these natural oils. However, this stripping of the hair and skin surface is the role of all detergents, not just sulphates.

The general perception that sulphates such as SLS and SLES are “harsher” than other surfactants is due to their anionic nature, meaning that they possess a negatively charged, hydrophilic head. Their hydrophobic tails are attracted to the dirt on the hair or skin’s surface and arrange to form a micelle, trapping the dirt inside which can then be washed away with water, as shown in the diagram below. As the hair and skin are also negatively charged, the anionic surfactant structure of sulphates is repelled from the surface, and because the head group of the detergent molecule is hydrophilic (water-liking), it is this mechanism that make these ingredients very efficient cleansers.

This doesn’t mean that all sulphate-based cleansers are inherently harsh and should be avoided. There are multiple formulation strategies that can be employed to reduce their harshness and potential to cause irritation, whilst maintaining effective cleansing performance. Sulphates are usually the primary surfactant in a cleansing system, but are rarely the sole surfactant used, often combined with other secondary (or co-) surfactants to deliver optimal performance. Secondary surfactants combined with anionic surfactants tend to be non-ionic or amphoteric in nature, as they are known for their efficient foam and mildness boosting properties, as well as their ability to aid stabilisation and viscosity building of a formulation.

The use of sulphate-based cleansers is a personal choice, and if you are happy with their performance there should be no reason to stop using them. If you have hair that is particularly fragile, or skin that is prone to sensitisation and you are not happy with their performance, you may want to avoid their use. But it is important to acknowledge that these ingredients are not inherently “bad” for everyone and can be used effectively in the design of cost-effective and efficient cleansing preparations in the personal care industry, when used at the appropriate usage levels.

Myth 2 – Sulphates can be hazardous and toxic

Ingredients such as SLS and SLES have been used in cosmetics for many years, and their safety has been explored through many studies. We have witnessed media headlines which have sparked concern amongst consumers and caused them to question their safety. Whilst cosmetic regulations remain a constantly evolving landscape, at the time of writing, there are no studies which list negative health connotations with these ingredients when used at appropriate usage levels.

For more information, check out this video, where Michelle of Lab Muffin Beauty Science explores some common misconceptions when it comes to SLES and its safety.

Myth 3 – Sulphate-free cleansers don’t foam or cleanse well

Sulphates are known for their ability to deliver effective cleansing performance, with excellent foaming capabilities. This is an important indicator for consumers that their cleansing products, whether it be for the hair or skin, are doing their job properly. Foaming is also important for the application experience, helping to spread the detergent easily over the hair and skin surface.

However, it is a common misconception that the foam and lather generated by such products is linked to their cleansing performance, when in fact it has no relationship with the quality of performance of the formulation. This presents a challenge for cosmetic formulators, to deliver a formulation that meets the expectation of consumers, both in terms of performance and ingredients used.

As I mentioned earlier, there is no direct replacement for sulphates, so a range of different ingredients must be used to deliver the same performance and experience demanded by consumers. Non-sulphate, anionic surfactants can be used as an alternative, in addition to co- surfactants. The surfactant blend can be designed to deliver optimal cleansing performance, whilst enhancing the mildness of the surfactant system, as well as delivering foam boosting properties, helping to optimise the performance of sulphate-free formulation to enhance user experience.

Myth 4 – Sulphate-free shampoos are better for coloured hair

It has long been believed that sulphates are responsible for hair colour fade when used in shampoos and should be avoided at all costs in order to preserve coloured hair for longer. However, this isn’t necessarily true and sulphate-based shampoos are not usually the sole culprit. Things such as UV radiation and the use of styling tools can contribute to hair colour fade, but the main cause is actually water from hair washing.

It’s important to understand the hair colouring process, where a high pH system is used to lift the hair cuticles and allow the dye molecules to penetrate the hair fibre into the cortex. After treatment, a low pH, post-dye conditioner is used to close the cuticles. However, this can be a damaging process as not all cuticles will lie flat again, leaving the hair surface exposed to further damage from additional grooming practices. 

When we wash our hair and apply water, this causes the cortex to swell and cuticles to lift as a result. This mechanism, combined with areas of damage on the hair surface where cuticles are damaged, means that water is able to penetrate into the cortex, gradually leading to hair colour fade as the dye molecules are soluble in water and are washed away.

Surfactants, used as detergents in shampoos, may play a part in the colour fading process by removing colour pigment in addition to dirt and oil during the washing process, but this phenomenon is not solely linked to sulphates, or any specific surfactant.

Hair colour fade unfortunately cannot be stopped completely, but the best way to maintain colour-treated hair for as long as possible is to protect the hair cuticle, repair any damage inflicted and keep the hair in an overall healthy condition. The use of conditioning treatments, heat protectants and cuticle sealing products can all help to keep the hair surface smooth, shiny and less prone to colour fade.

I hope you have found this blog helpful, and have learnt something new in our latest instalment of the myth busting series.