Surfactants, Detergents and Cleansing Agents in Cleansers

Surfactants, Detergents and Cleansing Agents in Cleansers

Surfactants, also called detergents, are key ingredients in skincare and cleansing products, responsible for removing dirt, oil, and impurities from the skin and hair. They work by lowering the surface tension between water and oils, allowing them to mix and be rinsed away. In this article I give surfactant examples of the most common detergents used in face and body cleansers. I will explain how they work to remove oil, dirt and sunscreen, and why they can injure the skin barrier. I will also talk about the difference in foaming and nonfoaming cleansers.

If you are looking for a facial cleanser- you can find one that is right for your skin type by taking the quiz or reading my blog about the best cleanser for your skin type.

The most irritating surfactants are anionic.

Sulfates are anionic surfactants.

The most gentle surfactants are nonionic or syndets.

Different types are combined to achieve desired cleansing and foaming effects.

Surfactants in Cleansers and How They Work

Have you ever wondered how skin cleansers work? The key lies in surfactants, which are the active ingredients that break down dirt and oil. Surfactants in cleansers help form micelles, which trap impurities and allow them to be rinsed away with water.

Cleansers come in many forms, from foaming to non-foaming, and the type of surfactant used plays a big role in how your skin feels afterward. Foaming cleansers often contain sulfate-based surfactants like sodium lauryl sulfate (SLS), which are effective but can be harsh on the skin, stripping away essential oils. That’s why sulfate-free cleansers are gaining popularity—they use gentler surfactants like cocamidopropyl betaine, which clean without damaging the skin’s barrier.

Understanding surfactants and sulfates can help you choose better cleansers for your skin type.

How Cleansers Clean The Skin

Surfactants are able to clean the skin because they are amphiphilic molecules, meaning they contain both polar and non-polar components. They have hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails.

When applied to the skin, the hydrophobic tails bind to oils, dirt, makeup, and oil based sunscreen, while the hydrophilic heads interact with water and water based ingredients.

This dual action creates spherical structures called micelles . The micelles surround and trap the dirt, sweat, makeup, skin creams, and SPF, making it easy to lift them away when the skin is rinsed with water.

The ability of surfactants to lift away dirt and oil is influenced by their charge.

Anionic surfactants, which carry a negative charge, are highly effective at binding to oily substances and creating a strong lather, making them powerful cleansers for removing oil, dirt, and makeup. That is why these are usually preferred by oily, resistant skin types.

Nonionic surfactants, which have no charge, are gentler on the skin and less likely to strip away natural oils, making them ideal for dry or sensitive skin types. They reduce surface tension and allow for the formation of micelles, which trap dirt and oil, enabling them to be rinsed away.

Amphoteric surfactants are less effective at removing oils and makeup than anionic surfactants. The ability of amphoteric surfactants to form micelles and their micelle size are be influenced by pH.

Types of Surfactants

In this section of this article, I will give examples of types of surfactants.

Surfactants can be classified into several types based on their charge and properties:

Anionic Surfactants: These have a negative charge and are strong cleansers, offering high foaming ability.

Amphoteric Surfactants: These can act as either positively or negatively charged, depending on the pH of the solution. Amphoteric surfactants are milder and more balanced, often used in gentler formulations.

Syndets (Synthetic Detergents): These are surfactants derived from synthetic sources, often formulated to be gentler on the skin. Syndets are typically used in “soap-free” cleansers and are ideal for sensitive skin as they cleanse without stripping the skin barrier.

Nonionic Surfactants: These carry no charge, are mild and less irritating, commonly used in leave-on products like lotions.

Cationic surfactants: These have a positive charge, are less common in facial cleansers but are often found in conditioners for their ability to reduce static and smooth the hair.

Each surfactant type offers different benefits, ranging from intense cleansing to gentler, skin-friendly formulations, making it essential to choose the right one based on your Baumann Skin Type.

Anionic Surfactants

Anionic surfactants, known for their negatively charged head, are highly effective cleansers and often used in products that require strong foaming action.

These surfactants are known for their ability to remove oils, dirt, and impurities from the skin and leave skin feeling very clean. These are great makeup and sunscreen removers.

Anionic cleansers can be harsh, stripping the skin of its natural lipids, which can compromise the skin barrier and lead to dryness or irritation. This makes them less suitable for people with sensitive or dry skin, but they are commonly used in formulations for oily skin due to their deep-cleansing abilities.

Anionic surfactants are more likely to cause irritation or allergic reactions, especially in individuals with compromised skin barrier.

Sulfates are anionic surfactants. Common examples include sulfates like sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES).

Effects of Water on Anionic Surfactants

The performance of anionic surfactants can be significantly affected by the type of water used.

In hard water, which contains high concentrations of minerals like calcium and magnesium, anionic surfactants can form insoluble compounds, leading to the formation of soap scum. This decreases their foaming ability and overall effectiveness, and can leave behind residues on the skin that may further irritate it. To counteract this issue, formulations with anionic surfactants may include chelating agents that bind to the minerals in hard water, allowing the surfactant to function more effectively.

Soft water, by contrast, improves the foaming action and cleansing power of anionic surfactants, as it lacks the mineral content that interferes with their performance.

Formulation of Anionic Surfactants in Cleansers

These anionic surfactants are often found in strong foaming facial cleansers for oily skin. Formulation considerations for anionic surfactants include balancing their strong cleansing power with ingredients that help reduce irritation. Often, they are combined with amphoteric or non-ionic surfactants to create a more balanced and less irritating product.

Cleansers with Anionic Surfactants

Anionic surfactants are generally known for their strong cleansing power, which can make them less ideal for “gentle” or “barrier-safe” cleansers. However, there are milder forms of anionic surfactants, such as disodium cocoyl glutamate , potassium cocoate , and potassium cocoyl glycinate , which are all derived from coconut oil. These gentler surfactants are frequently used in oily skin cleansers due to their ability to remove excess sebum effectively. Additionally, they may be mixed with milder surfactants, like amphoteric or non-ionic surfactants, to reduce their overall strength and minimize their potential for irritation, making the formula more balanced for long-term use.

Disodium Cocoyl Glutamate

Disodium Cocoyl Glutamate is a mild, anionic surfactant derived from coconut oil and glutamic acid. It is used in gentle cleansers due to its low potential for irritation. It effectively removes dirt and oil while maintaining the skin’s moisture barrier, making it ideal for sensitive or dry skin. It is sulfate-free and eco-friendly.

Potassium Cocoate

Potassium Cocoate is the potassium salt of fatty acids derived from coconut oil. It is an anionic surfactant, meaning it carries a negative charge. It is commonly used in natural soaps as a gentle cleansing agent, particularly in liquid soap formulations. It is not a sulfate and is typically considered much milder than sulfate-based surfactants.

Potassium Cocyl Glycinate

Potassium Cocoyl Glycinate is derived from coconut oil and glycine, an amino acid. It is a mild surfactant and cleanser often used in facial cleansers and body washes. Its anionic nature means it has a negative charge, which helps to remove dirt and oil from the skin, but it is much gentler compared to sulfates like SLS or SLES.

Is often found in Gentle Cleansers like Zerafite.

Sodium C14-16 Olefin Sulfonate

Sodium C14-16 Olefin Sulfonate is a strong anionic surfactant commonly found in cleansers for oily skin due to its effective oil and sebum-removing properties. It helps control shine and deeply cleanses, but frequent use or high concentrations can disrupt the skin’s natural lipid barrier, leading to dryness and irritation. To make it gentler, it’s often diluted with milder surfactants like Cocamidopropyl Betaine, reducing irritation while maintaining cleansing efficacy.

Amphoteric Surfactants

Amphoteric surfactants, which have both positive and negative charges depending on the pH of their environment, are versatile and often used in gentle cleansers. These surfactants adapt to different pH levels, making them ideal for a wide range of skin types and conditions. Amphoteric surfactants are typically sulfate-free and are considered milder than anionic surfactants like sodium lauryl sulfate (SLS). This makes them much gentler on the skin barrier, helping to cleanse without stripping essential lipids. They are generally safe for the skin and well-tolerated, even for sensitive skin types. Amphoteric surfactants, such as cocamidopropyl betaine , are popular in sulfate-free cleansers for their ability to cleanse effectively while maintaining the skin’s moisture balance.

These surfactants are suitable for both oily and dry skin, as they cleanse gently without over-drying or irritating the skin. Their mild nature makes them less likely to cause allergic reactions or irritation compared to harsher surfactants. However, like any ingredient, some individuals may experience sensitivity or irritation, though this is rare. Overall, amphoteric surfactants are a safe, skin-friendly option for a variety of skin types, offering gentle cleansing without damaging the skin barrier.

Effects of Water on Amphoteric Surfactants

When amphoteric detergents are used in hard water, the presence of calcium and magnesium can affect their performance. Hard water may reduce foaming and cleansing ability by interacting with the amphoteric surfactants, though they tend to be less affected than anionic surfactants.

Soft water, on the other hand, allows amphoteric surfactants to foam better and perform optimally by preventing the interference of minerals

Gentle Cleansers with Amphoteric Surfactants

Amphoteric surfactants, such as cocamidopropyl betaine and cocoamphoacetate, can adapt to different pH levels, making them versatile and ideal for gentle cleansers.

These surfactants are mild and less likely to irritate the skin, commonly used in sensitive or combination skin products.

For oily skin cleansers, they may serve as the primary surfactant or be combined with stronger anionic surfactants. When blended, amphoteric surfactants help reduce the irritant potential of the formulation, balancing effective cleansing with skin barrier protection

Disodium Cocoamphodiacetate

Disodium Cocoamphodiacetate is a mild surfactant that can have both a positive or negative charge depending on the pH of the solution, making it amphoteric. It is often used in gentle cleansers, baby products, and sensitive skin formulations because of its mildness. It helps create foam but is non-irritating at a medium pH , and it’s sulfate-free.

Cocamidopropyl Betaine

Cocamidopropyl Betaine, derived from coconut oil, is a mild amphoteric surfactant commonly used in sulfate-free formulations. It is not a sulfate and can act as both anionic and cationic, depending on pH. With moderate detergent strength, it provides gentle cleansing without the harshness of sulfates like SLS. Generally low in irritation, it’s suitable for sensitive and eczema-prone skin. Although sourced from coconuts, it’s considered semi-synthetic due to the chemical processes involved. Often added to cleansers, Cocamidopropyl Betaine helps make formulations gentler by diluting stronger surfactants, reducing potential irritation while maintaining effective cleansing.

Nonionic Surfactants

Non-ionic surfactants are a class of surfactants that do not carry an electrical charge, making them much gentler on the skin than their anionic or cationic counterparts. They work by having both hydrophobic and hydrophilic parts in their molecular structure, allowing them to break down oils and dirt and form micelles that cleanse the skin. Since they lack a charge, non-ionic surfactants don’t disrupt the skin’s lipid barrier as much, making them ideal for sensitive skin. Most non-ionic cleansers are sulfate-free , as sulfates are typically anionic surfactants, known for being harsher and more likely to strip the skin’s natural oils.

Effects of Water on Non-Ionic Detergents

Hard water, which contains high levels of calcium and magnesium, doesn’t directly affect non-ionic surfactants because they don’t depend on ionic interactions to clean. However, hard water can reduce the effectiveness of some cleansing agents by creating soap scum or deposits, whereas soft water, which has fewer minerals, allows surfactants to work more efficiently. Non-ionic surfactants tend to perform well in both types of water without significant changes in cleansing ability.

Gentle Cleansers with Non-ionic Surfactants

Non-ionic surfactants, such as decyl glucoside and coco glucoside, are gentle, uncharged molecules used in sulfate-free cleansers. They are effective at lifting dirt and oil while being less harsh on the skin barrier compared to anionic surfactants. These surfactants are often used in formulations for dry or sensitive skin due to their mild nature.

In cleansers for oily skin, non-ionic surfactants may be combined with stronger surfactants to balance effective cleansing with gentleness, helping maintain skin hydration and reduce the risk of irritation.

Types of Non-Ionic Surfactants

Ceteareth-20

This non-ionic surfactant acts as an emulsifier, helping to blend oil and water in formulations. It is known for being mild and non-irritating, making it suitable for sensitive skin. While it’s not a primary cleanser, it helps with texture and ensures uniform distribution of other ingredients. It’s generally barrier-safe and does not strip the skin of natural oils.

Decyl Glucoside

Decyl Glucoside, a mild nonionic surfactant derived from glucose and coconut oil. As a nonionic surfactant, it has no charge, which makes it exceptionally gentle on the skin, as it doesn’t disrupt the skin barrier or cause irritation. This makes it ideal for sensitive or dry skin. It’s often mixed with stronger surfactants to balance the formulation, reducing harshness while still providing effective cleansing. Its nonionic nature is key because it provides gentle cleansing without the foaming and stripping associated with charged surfactants.

Glycereth-2 Cocoate

Glycereth-2 Cocoate is a nonionic surfactant derived from glycerin and coconut oil. As a nonionic surfactant, it has no charge, which makes it gentle on the skin. It cleanses by breaking down oils and dirt, allowing them to be rinsed away without disrupting the skin’s natural barrier. Its emollient properties also help retain moisture, making it ideal for cleansers that balance cleansing and hydration. Occasionally labeled as PEG-2 Cocoate , it reduces irritation in formulations with stronger surfactants.

Polysorbate 20

This non-ionic surfactant is used for emulsification and solubilizing ingredients like oils in water-based products. It is gentle and non-drying, making it appropriate for sensitive or dry skin types. Its cleansing ability is mild, and it does not disrupt the skin’s natural barrier.

Sorbitan Isostearate

This non-ionic surfactant is derived from sugar alcohols and fatty acids, functioning as an emulsifier. It’s considered non-irritating and mild. Sorbitan Isostearate helps maintain the skin’s hydration while offering light cleansing without compromising the skin barrier.

Sucrose Laurate

Sucrose Laurate is a nonionic surfactant derived from the esterification of sucrose and lauric acid (from coconut or palm oil). It gently cleanses by reducing surface tension, allowing dirt and oils to be rinsed away without disrupting the skin barrier, making it suitable for sensitive skin. Lauric acid imparts antimicrobial properties , while the sucrose component offers moisturizing benefits similar to a humectant, helping to retain skin hydration.

Cationic Surfactants

Cationic surfactants, such as benzalkonium chloride and cetrimonium bromide, carry a positive charge, making them effective in specific roles like antimicrobial agents and conditioning.

Cationic surfactants can be quite irritating to the skin, especially for those with sensitive or dry skin types. Due to their strong positive charge, cationic surfactants often bond tightly to the skin and hair, which can disrupt the skin barrier and lead to dryness or irritation. As a result, they are generally not recommended for sensitive or dry skin cleansers. These surfactants are more commonly found in hair conditioners and disinfecting products such as hand soaps. This is one of the main reasons you should not wash your face with shampoo or hand soap.

Effects of Water on Cationic Detergents

Cationic detergents, like benzalkonium chloride and cetrimonium bromide, are impacted by water hardness, pH, and foaming ability.

In hard water, high levels of calcium and magnesium can interfere with the detergent’s ability to produce a vigorous foam. These minerals bind to the surfactants, reducing their foaming and cleaning effectiveness, which makes it harder to achieve a rich lather.

In contrast, soft water, which has fewer minerals, enhances foaming action, allowing cationic detergents to create a more vigorous foam and work more efficiently.

The pH level also influences the behavior. In slightly acidic environments (lower pH), cationic surfactants tend to perform better, maintaining their positive charge for more effective binding. However, in more alkaline environments, their effectiveness and foaming potential may decrease, reducing their ability to properly cleanse.

Saponins: Natural Surfactants

Saponins are naturally occurring compounds derived from plants that act as surfactants, making them valuable in organic and natural skincare lines . They are composed of both water-soluble and oil-soluble components, allowing them to cleanse the skin effectively by forming a lather that lifts dirt, oils, and impurities. They are widely used in organic or natural cleansers.

How Saponins Work

Saponins cleanse through their amphiphilic structure, meaning they have both water-attracting (hydrophilic) and oil-attracting (hydrophobic) components. Though they don’t carry a significant charge, they work similarly to surfactants by lowering the surface tension between water and oils. This allows them to form a foam when mixed with water, which helps to lift dirt, oils, and other impurities from the skin. However, saponins are not as effective as synthetic surfactants at forming micelles—the structures responsible for trapping dirt and oil—meaning their cleansing action is gentler and less aggressive.

The effectiveness of saponins in cleansing is influenced by pH. They work best in a neutral to slightly acidic environment, which aligns with the natural pH of the skin (around 5.5). However, this pH sensitivity can limit their versatility, as they may not perform as well in formulations with a higher or lower pH.

Effects of Water on Saponins

Saponins can form deposits in hard water, reducing their effectiveness and leaving residue.

The cleansing action of saponins is optimal at a neutral to slightly acidic pH, which makes them gentle but can limit their versatility in different formulations. This is one reason why it is hard to find good organic facial cleansers and body washes.

Pros and Cons of Natural Saponin Surfactants

While saponins offer an environmentally friendly and gentle cleansing option, they have unique properties compared to synthetic surfactants. Here’s an overview:

Pros:

Gentle on skin

Derived from plants

Moderate cleansing ability

Make a rich foam

Cons:

Foam is less stable.

Lower cleansing power

Not as effective at removing heavy oils or makeup.

High concentrations have Irritation potential

Overall, saponins offer a natural and gentle alternative for those looking for mild, eco-friendly cleansers, but they are better for dry skin types than oily skin type because of their limited cleansing abilities.

Examples of Natural Saponins in Cleansers

Saponins are found in natural skincare formulations for their gentle cleansing properties and their ability to create foam while maintaining the skin’s natural moisture balance.

Here is a list of natural plan derived saponins that are used to cleanse the skin:

Aesculus Hippocastanum Seed Extract (Horse Chestnut)

Camellia Oleifera Leaf Extract (Tea Seed)

Glycyrrhiza Glabra Root Extract (Licorice Root)

Glycine Soja (Soybean) Seed Extract

Gleditsia Sinensis Extract (Chinese Honey Locust)

Quillaja Saponaria Bark Extract (Soap Bark Tree)

Sapindus Mukorossi Fruit Extract (Soapnut)

Saponaria Officinalis Leaf/Root Extract (Soapwort)

Trigonella Foenum-Graecum Seed Extract (Fenugreek)

Yucca Schidigera Root Extract (Yucca Plant)

Syndet Detergents

Syndets , short for synthetic detergents , are cleansing agents made from synthetic surfactants rather than traditional soap-based ingredients. They are often formulated with a neutral or slightly acidic pH, making them much gentler on the skin than soap, which tends to be more alkaline. Syndets work by effectively cleansing the skin while maintaining the integrity of the skin barrier, reducing irritation and dryness, making them suitable for sensitive and dry skin types. A well-known example of a syndet bar is Dove Soap , which was invented by Unilever (makers of Ponds and Dove) as one of the first syndet bars on the market.

Syndet bars typically contain mild surfactants like sodium cocoyl isethionate or alpha olefin sulfonates , which cleanse without stripping away the skin’s natural oils. Their formulation allows for effective cleansing in both hard and soft water, without the soap scum often associated with traditional soap in hard water. This combination of gentle cleansing and compatibility with different water types makes syndet bars a popular choice for people with sensitive skin.

Effects of Water on Synthetic Detergents

Synthetic surfactants perform differently in hard water versus soft water.

In hard water, which contains high concentrations of calcium and magnesium ions, syndet bars are much more effective than traditional soap. They produce less soap scum, as the synthetic surfactants don’t react with the minerals to form insoluble deposits.

In soft water, syndet bars perform optimally, producing a richer lather and cleansing effectively without any interference from minerals.

Examples of Synthetic Detergents

These are syndets found in facial cleansers and body wash:

Alpha-Olefin Sulfonate

Disodium Laureth Sulfosuccinate

Sodium Cocoyl Glycinate

Sodium Cocoyl Isethionate

Sodium Cocoyl Sulfate

Sodium Lauroyl Glutamate

Sodium Lauroyl Methyl Isethionate

Sodium Lauroyl Sarcosinate

Sodium Lauryl Sulfoacetate

Sodium Methyl Cocoyl Taurate

Summary

There are many different cleansing agents added to facial cleansers and body washes:

Anionic surfactants carry a negative charge, making them highly effective cleansers but potentially more irritating and stripping to the skin. Sulfates are anionic surfactants.

Amphoteric surfactants can have both positive and negative charges, depending on the pH. This makes them versatile.

Nonionic surfactants have no charge, making them the mildest option. They are less irritating, help maintain the skin’s barrier, and are ideal for sensitive skin. Examples include decyl glucoside and polysorbates.

Cationic surfactants carry a positive charge and are often used for their antimicrobial properties, but they can be irritating and are less commonly used in facial cleansers. Examples include benzalkonium chloride and cetrimonium bromide.

Saponins, derived from plants, are natural surfactants with both hydrophilic and hydrophobic components. They foam well and are often used in natural or organic cleansing products, but they are less common in mainstream cleansers.

Synthetic detergents are made from synthetic surfactants and are formulated to have a neutral or slightly acidic pH, making them much gentler on the skin.

Cationic surfactants provide antimicrobial properties but can be harsh and irritating.

Confused about which cleanser to use?- We can help! Take our skin type quiz and you can shop for face cleansers and body washes using your skin type octagon.

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