When developing sulfate-free shampoos, the main challenge faced by the formulator is to achieve foaming and viscous products. The selection of sulfate-free surfactants is essential to achieve high performance products.
Surfactants are essential components in cosmetics. From body hygiene to skin moisturising cosmetics, and even tooth and nail care products, surfactants are found performing their function efficiently.
In hygiene products, surfactants are the ingredients responsible for cleansing the skin and producing foam. For a long time, surfactants containing sulfates have been the basis of these formulations, because they fulfil these two missions well, and they also thicken easily resulting in viscous products that are easy to use. However, consumers are becoming more and more demanding when it comes to cosmetic ingredients, and they have driven the industry to replace these traditional surfactants with sulfate-free surfactants.
The increasing use of sulfate-free surfactants
Some sulfate-free surfactants are positively valued because they are mild to skin and hair, and additionally, in certain combinations, cleaning efficacy similar to sulfate systems can be achieved.
The challenge in sulfate-free shampoo formulations is to achieve formulas that produce rich foams and thicken easily (link to thickeners). And these are aspects the consumer takes very much into account when assessing the quality of a hygiene product. The appearance, density and permanence of the foam together with the touch of the product when applied are crucial parameters.
Foam and sensoriality in cosmetic formulations
The consumer of cosmetic cleansing products perceives foam as a benefit of the formulation and relates it to a higher detergent efficiency of the product. Therefore, it is important to take into account the foaming characteristic in cosmetic formulations for cleaning purposes.
The combination of surfactants determines the amount and volume of foam
There are two characteristics to highlight regarding the foaming study of a sulfate-free shampoo:
- The quantity of foam related to the volume of foam it can generate.
- The quality of foam which includes duration, foam density and average bubble size.
What role do surfactants play in sulfate-free shampoos?
In cosmetic cleaning formulations, detergent agents are surfactants: amphiphilic molecules with a structure formed by zones with different behaviour, a hydrophilic one (with affinity towards water) and a lipophilic one (with affinity towards grease). This structure allows them to be affine to substrates of different nature (polar and apolar), which gives them detergent and foaming capacity.
Surfactants are usually classified according to the polarity of the polar group into anionic, cationic, amphoteric and non-ionic.
Foaming sulfat-free surfactants
Anionic surfactants are generally the most foaming surfactants. Within this group, sulfates have good detergent and foaming properties and the cost is low. Therefore, they are the most commonly used anionic surfactants in cleansing cosmetics. The most common is sodium lauryl ether sulfate (INCI: Sodium Laureth Sulfate).
However, in recent years, alternatives to sodium lauryl ether sulfate, which are better tolerated and less irritating to the skin, are being sought, and the demand for other more dermocompatible or natural surfactants is growing. Sulfate-free surfactants are used to formulate sulfate-free cosmetics and, are often associated with milder and less irritating products.
Sulfate-free surfactant combinations must be optimised to achieve products that form rich and creamy foams. An added difficulty in sulfate-free products is to build up a viscosity that facilitates the use of the product and, this can be achieved with thickeners.
Surfactants for natural cosmetics
Quimidroga offers various surfactants derived from natural ingredients, sulfate-free, of different natures and with different properties. When formulating with these surfactants, various properties are sought:
- Achieving effective products.
- Achieving good foaming properties.
- Obtaining these properties at reasonable product costs.
- Stabilising these formulations to meet pH, transparency or viscosity requirements.
Natural surfactants are usually derived from vegetable oils and butters.
In Quimidroga’s cosmetics catalogue you can find sulfate-free surfactants (some are natural surfactants) with different detergent and foaming properties, and a wide range of thickeners. From Quimidroga’s laboratory, all these surfactants are characterised and optimised formulations of sulfate-free shampoos are developed to achieve combinations with the maximum benefits possible for each application.
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