Emollients sound and often look (chemically speaking) like they could be emulsifiers but in fact they perform a useful and very different job, helping you to create something truly unique and beautiful. The primary job of an emollient is to help you modify or change the feel of the emulsion that you wish to create by creating better slip or gloss, enhanced skin penetration or barrier function, giving a light and airy or lubricious and cushiony feel on application or creating a dry and powdery of velvet-like finish. There are hundreds if not thousands of emollients to choose from ranging from those that are organically derived to the most cutting-edge of synthetic chemistry and what is also exciting is that many of these emollients have multi-functional benefits.

In a nutshell the emollients are a group of functional chemicals that change the feel of your emulsion based product. Many (but not all) emollients sit in the oil-phase of the emulsion where they modify the emulsions chemical and physical properties. Now all ingredients will affect the feel of your product to some extent so to further define and identify an emollient we have to add a little more to its description. Emollients are typically used at between 1-10% in a formulation and do not tend to have a large impact on the formulations viscosity (thickness) or flow. While that sounds very complicated in practice it need not be as much of the work into the compatibility, effect and feel of the different emollients has already been done by the ingredient manufacturers meaning that all we have to do is try it out for ourselves!

Let's have a look at a few examples of Organic, Natural and Synthetic emollients to get a better idea of what we are talking about.

Organic Emollients

Direct from nature - basic preparation and extraction only.

Waxes and Butters - Things like Beeswax, Shea and Cocoa Butter all affect the feel of your emulsion and as such could be called emollients. However, as they are usually put into a product at relatively high levels to help thicken or stabilise it and even at lower levels these will change the flow and thickness of your product. Therefore a more accurate description of their function would be thickener, bodifying agent or consistency factor. To summarise, in an organic formulation where you have less choice in emollient, waxes and butters can be carefully chosen and blended to help you achieve a range of feelings. However, there are limits to the effects you can achieve by using these alone.

Vegetable Oils - As with the waxes and butters, the key oil in your oil phase is usually chosen for reasons other than just its feel - things like oxidative stability, vitamin and fatty acid content, story and origin, colour or smell. However, the properties above are all related to how the oil feels - I am sure we have all noticed how different Olive Oil feels from Jojoba Oil (which is actually a liquid wax) and this is due to its chemistry. A wide range of vegetable oils are available to the organic formulator and as such it is possible to create blends that give you the base, story and actives that you desire while subtly changing the feel and appearance of the oil phase. However, as with the waxes and butters, there are limits to what you can do with organic oils.

Natural Emollients

Vegetable feedstock with allowable modifications to the chemistry

Vegelan (Vegetable Squalane) - Squalane is a key component of olive oil and sometimes as cosmetic chemists we want the heart of an ingredient without the body, the cushiony feel properties without the oil slick and this is a good example of that. Basically Squalane is separated out from the bulk of the olive oil via a physical process. This process does not involve the addition of any other chemicals and as such results in a pure and natural fraction of the olive oil.

This fraction of the olive oil is non-greasy and leaves a silky feeling on the skin. It spreads easily and is highly compatible with the skin making it a true and very useful emollient. This is typically used at between 2-10% in emulsions.

MCT Oil (Caprylic Capric Triglyceride) - This is another example of an emollient created through a series of simple physical processes. Glycerine and medium chain fatty acids are extracted from either coconut or palm oil and reacted together to form an ester. This ester is soluble in oils but due to its slight polar nature it can also blend into some alcohols and acids making it very useful for enhancing the solubility of flavours and fragrances while enhancing the skin feel of a product. MCT oil helps to remove the stickiness and improves the spread ability of natural emulsions.

Lauryl Lactylate - This light natural ester is based on alpha hydroxyl acids which means that as well as bringing a light and non-sticky feeling to your emulsion it also boosts the efficacy of skin-renewal products. This light and velvety emollient makes it possible to create elegant and sophisticated emulsions.

Oleyl Oleate - This is another modified fraction of vegetable oil that boosts the gloss of a natural formulation while giving a cushiony and rich emollient feel to an emulsion. Another benefit of this emollient is that it helps to disperse pigments which means it is great in colour cosmetics and sunscreens containing zinc or titanium.

Isopropyl Myristate - This commonly used vegetable derived emollient has a long history of use in cosmetic formulations as it is able to give a product a dry and quick-drying feeling rather like that achieved with silicones. However, one down side is that it has a slight comedogenic affect (it can block pores) in susceptible individuals so while it is OK for products for babies, kids or older adults it is not great for teenagers or any products targeting problem skin.

Synthetic Emollients

C12-15 Alkyl Benzoate - This is a widely used emollient in cosmetics because it is a great pigment disperser, has a light and non-greasy skin feel and is cost effective. While this could theoretically be produced from vegetable based feed stock, this is synthetic as it is built on a petroleum oil base. However, the fact that it is chemically stable, has a low odour and colour and is great at taking away greasiness make it an invaluable addition to any cosmetic chemists tool kit.

Silicone Oils - The most widely used silicone emollients are the dimethicone series which range in thickness (centistokes or CST). Common varieties are the 50 CST, 100 CST, 350 CST and 1000 CST. These range in feel from very light and quick evaporating to rich, slippy and lubricious. The main objection to this family of silicones is that they contain petroleum derived methyl groups which makes them un-sustainable from an environmental perspective.

PEG-7 Glyceryl Cocoate - This multi-functional ingredient enhances the lipid (fat) layer of the skin leaving it feeling soft and smooth. It is a good example of how natural ingredients are blended with synthetics to form a new, functional chemical. In this case the glyceryl cocoate comes from coconut oil and glycerine while the PEG -7 is a Polymer of Ethylene Glycol which is petroleum derived (although this could also come from vegetable oil). In this example the PEG part actually gives this emollient some surface-active powers and as such it can also help solubilise your essential oils and actives - a true multi-functional feel enhancer.

As you can see from this small selection above feelology is a really interesting area of your formulation and we have emollients to thank for that. If you have been inspired to try more why not join your New Directions technical team as we put this theory into practice in our new workshop.

Your future emulsions feel great!

Amanda Foxon-Hill

20 June 2011