NATURALS
raw materials used alongside and often blended with synthetic emulsifiers are in fact natural and 100% plant derived. Examples of these are cetyl alcohol, cetearyl alcohol, stearic acid and glyceryl stearate. With some careful formulating these popular natural materials can be used alongside natural emulsifiers to obtain a great texture.
Water thickeners One of the most common ingredient categories in cosmetics that is targeted for replacement with natural ingredients is rheology modifiers and thickeners. Carbomer, a polymer of acrylic acid, is a useful and highly functional raw material specifically developed for the cosmetic industry to improve the feel, stability, and viscosity of a wide variety of cosmetic formulations, for example, face creams, lotions, facial and body gels, hair gel, hand sanitiser and many more. The INCI name for carbomer is usually listed
as ‘Carbomer’ but close derivatives include Acrylates/C10-30 Alkyl Acrylate Crosspolymer and Acrylates Copolymer. Most of them produce highly viscous,
transparent gels in water at a low use level. The texture and skin feel of carbomer make it a difficult product to replace effectively with natural alternatives. The key to replacing carbomer effectively is defining what function it has in the selected formulation. If transparency is the key property, and the high viscosity and suspension characteristics are not that important, then products such as cellulose gum, transparent xanthan gum and sclerotium gum could be considered. If a high viscosity is required but transparency
is not important, for example in a cream formulation, then gums such as guar, tara and gellan could be considered. Table 2 shows some natural thickener systems based on the functional properties required.
Surfactants
The all-purpose surfactant Sodium Laureth Sulphate (SLES) has both natural and synthetic molecular parts and is often targeted for removal by formulators due to ethoxylation of the Lauryl group. There are other reasons for this, not just the synthetic aspect, but also because it is a known eye and skin irritant and may not be suitable for some applications.
Primary or Secondary
TABLE 1: NATURAL EMULSIFIER SYSTEMS Natural Emulsifier type
Polyglycerol Esters (High HLB)
Polyglycerol Esters (Low HLB)
Sucrose Esters
Natural Anionic Emulsifiers
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Examples
Polyglyceryl-10 Stearate, Polyglyceryl-6 Oleate
Polyglyceryl-2 Triisostearate, Polyglyceryl-3 Polyricinoleate
Sucrose Laurate, Sucrose Stearate
Sodium Stearoyl Lactylate, Sodium Stearoyl Glutamate, Glyceryl Stearyl Citrate, Potassium Cetyl Phosphate
TABLE 2: NATURAL THICKENERS Key Property Required
Transparency High viscosity Stabilisation Suggested Natural Ingredients
Cellulose Gum, Xanthan Gum (certain grades), Sclerotium Gum, Locust Bean Gum (Carob), Carrageenan
Tara Gum, Guar Gum, Gellan Gum, Konjac, Carrageenan
Microcrystalline or microfibrillated Cellulose, Xanthan Gum, Sclerotium Gum, Gellan Gum
SLES is a very effective and cheap ingredient
and is not easy to replace due to its superior foam production and the fact it is salt thickened, meaning that any alternative system probably has to be thickened using another technique such as a natural gum, giving a less favourable - and more expensive - rheology. The secondary amphoteric surfactant
Cocamidopropylbetaine is less often targeted for removal, however it does contain synthetic entities so in very natural products is sometimes replaced with coco-betaine, which is 100% naturally derived. Common natural replacements are shown in
Table 3. It is worth mentioning that performance is usually compromised by substituting the synthetics and effective foaming and cleansing is difficult to achieve using only natural ingredients.
Emollients Emollients is an easy category of ingredients to replace with natural alternatives and often natural oils and esters are the first choice for
TABLE 3: SURFACTANT SYSTEMS TO REPLACE SYNTHETICS Key Property Required
Glucosides (Decyl, Lauryl, Coco)
Saponins (e.g. Yucca, Quillaja, Soapnut, Soapwort)
Sucrose Esters (Laurate, Myristate)
Biosurfactants (Sophorolipids, Glycolipids, Rhamnolipids)
Amino Acid based surfactants (e.g. Sodium Cocoyl Glycinate)
Primary Secondary/Foam Booster Secondary Primary or Secondary Primary or Secondary Classification Non Ionic Non Ionic Non ionic Non ionic Anionic Notes On Use
Popular natural mild surfactants based on glucose. Not salt thickened.
Not highly cleansing or foaming on their own but can be an effective additive.
Effective but expensive.
Fermentation technology, foaming performance poor but acceptable cleansing.
Very effective but relatively expensive.
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Synthetic Emulsifier Replaced
Ethoxylated esters e.g. PEG-100 Stearate, PEG-40 Hydrogenated Castor Oil, Polysorbate 20
Laureth-3, Steareth-2 High HLB Ethoxylates
High HLB Ethoxylates
Notes On Use
Need to select those grades that are transparent. High levels of use may not be completely transparent.
Viscosity usually increases with use level, however high levels are associated with unfavourable sensory effects such as pilling.
Thixotropy (rheology associated with shear thinning) is often a sign that a thickener is good for stabilising emulsions.
many formulators due to their sensory properties. Most vegetable oils will be classified as natural and COSMOS approved. However, it is worth checking with the
supplier how the oil was extracted, as some are hexane-extracted from the seed or nut - making them unsuitable for COSMOS approval. For true natural classification, oils should be cold pressed or CO2 extracted. There are a huge number of vegetable derived
esters available and these can be considered COSMOS natural due to esterification being a permitted chemical process reaction. Many different sensory characteristics can be obtained with esters, from very light and volatile to heavy and substantive depending on the chain length, degree of saturation and branching of the fatty acids that make up the ester. The synthetic emollient group mainly consists
of paraffin oil and derivatives such as petrolatum, synthetic emollient esters and silicones. Silicones are worth a special mention as they are quite difficult to replace, particularly in haircare applications. It is hard to reproduce the slippery feel, smoothing effect and spreadability of silicones, as is the high heat stability in applications such as heat protection spray or serum. Hair conditioners that are silicone free sometimes lack the smoothing effectiveness of those containing silicones, although ‘silicone free’ is a popular claim for those consumers who believe build-up on hair to be a problem. Table 4 shows a selection of popular natural emollients and their properties.
Colours Essential in cosmetics to add interest to a toiletry product, or as a decorative colour cosmetic, the use of colours in cosmetics has always been a challenge. In natural cosmetics, it is difficult to achieve the vibrancy and longevity of a synthetic colour and some compromises need to be made.
April 2024 PERSONAL CARE
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