To give you a deeper understanding of the challenges cosmetic chemists grapple with when formulating winning products, I wanted to take things back to basics with a beginners’ science class. Welcome to Cosmetic Chemistry #101. Will you pass or will you fail?
OIL-IN-WATER VS WATER-IN-OIL
One of the first things we consider when formulating a product is whether an oil-in-water (O/W) or water-in-oil (W/O) formula will give the desired outcome. Each type has its pros and cons, and some product categories naturally lend themselves to one or the other.
What is the difference between an oil- in-water and a water-in-oil-formula? You’ve no doubt heard the old adage, “oil and water don’t mix.” Well, they do – but it requires the help of an emulsifier. An oil-in-water (O/W) emulsifier allows oil droplets to be dispersed in a water base. The opposite applies for a water-in- oil (W/O) emulsifier – that is, it enables water droplets to be suspended in an oil-based product.
As for which one is best? That largely depends on the type of product being formulated, and the skin type it is targeted towards. Often used in creams and serums, oil-in-water skincare formulas are generally lighter, easily absorbed, able to layered and quick drying. However, they can also be sticky or tacky due to the gums used to thicken them – especially if they are a serum.
Mostly used in sunscreens and rich night creams, water-in-oil formulas are more moisturising; however, they will often leave a residue of oil. While not ideal for an oily or acne- prone skin, they’re great for clients with lipid-dry skin who require something deeply nourishing.
SUNSCREENS & SHINE
Did you know the chemical and mineral filters used in sunscreens generally perform better in an oil base – that is, a water-in-oil formula? Oil helps increase the performance of sun protection chemicals, making it easier for chemists to achieve a higher SPF rating for their formulas. To ensure sunscreens perform
at their optimal function (to protect the skin from damaging UV rays), we therefore tend to formulate in an oil base, rather than a water base.
However, formulating this way does not always give the best cosmetic outcome. A greasy feel or look is the reason consumers are often non- compliant, particularly those with combination or oily skin.
While more difficult, it is also possible to create an oil-in-water sunscreen formula. The majority of the formula being water rather than oil results in a formula that is lighter, mattifying and easy to spread, with greater cosmetic appeal to many consumers.
COSMECEUTICAL CLEANSERS, SURFACTANTS & CHARGE
There are a number of factors that distinguish a quality cosmeceutical cleanser from a standard cleanser, starting with the surfactants that are used.
Did you know cleansers use multiple surfactants in just one formula?
You may not know this, but for cleansers to perform at their optimal function (to clean the skin thoroughly), we formulate them with multiple surfactants (the ingredients that create bubbles). The more surfactants used in a cleanser, the more expensive it becomes to formulate.
Did you know cleansers have charge?
Some surfactants will come with charge and some without charge. The charged surfactants are called anionic and the neutral ones are called non- ionic. Anionic surfactants will use the charge and foam to remove dirt and oil from the skin. Non-ionic surfactants will use surface pressure and foam to remove the dirt, resulting in a gentler, but less thorough clean.
Achieving a balanced clean
Cosmeceutical cleansers are unique because they will formulate with both negative and neutral charges to achieve the best result, where standard (non- cosmeceutical) cleansers will not. This is what makes a cosmeceutical cleanser special – the fact that we don’t rely on just one surfactant, but multiple to help clean the skin.
It’s a tricky business, however, and formulating a cleanser with too much charge can lead to unwanted irritation. There is definitely an art to formulating a cosmeceutical cleanser and it takes experience to know the right charge (percentage of surfactant) to formulate with.
Cream versus foaming cleansers
Have you ever wondered then, how a cream-based cleanser cleans the skin if it doesn’t create bubbles? While the high levels of surfactants in foaming cleansers results in a deep, thorough clean, cream-based cleansers help to gently dislodge dirt and oil with surface pressure, rather than the use of foam.
The deep cleansing action of foaming cleansers makes them best suited
to an oily or combination skin – as they can be drying, whereas cream-based cleansers are an excellent option for dry, mature and sensitive skin. Typically formulated with non-ionic surfactants, they are more gentle and less disruptive to the acid mantle and skin barrier.
Are actives in cleansers a waste of time?
I’m often asked this question and the answer is, yes and no. While I am a firm believer in the benefits of acids and Vitamin C in cleanser (which I’ll soon discuss), the truth is most actives have little benefit when added to a cleanser. Actives like peptides and most vitamins need to be on the skin for a prolonged period of time for them to work and have a therapeutic effect to the skin.
So, while savvy marketers will often promote cleansers as containing “actives”, these products often won’t do what you may think they are doing.
Alpha-hydroxy and beta-hydroxy acids, such as glycolic and salicylic acid, can be a great inclusion in cleaners for ageing or congested skin. Helping to cleanse and refine the skin, the acids help to speed up cellular turnover and unclog pores for a clearer, smoother complexion. And benefits can be seen even with just a 30 second exposure once or twice daily.
Cleansers are therefore a great way to expose your client’s skin to acids if a leave-on product will be too intense or irritating.
Vitamin C cleansers
Did you know cleansers can use Vitamin C to help protect the skin? As mentioned, most actives don’t work if they don’t remain on the skin and are therefore redundant in cleansers. Vitamin C is a little different. With an antioxidant rather than therapeutic effect (when used in a cleanser), it can instantly neutralise free radicals on impact.
HOW TO READ AN INGREDIENT LIST
To get an idea of the percentage of an ingredient used in a particular product, keep an eye out for Phenoxethanol on the ingredient list. This very common and trusted broad-spectrum preservative is used in many products at a concentration of 1%. Any ingredient that is listed below it is included at a concentration of less than 1%.
Another fun formulating fact – ingredients that are included at less than 1% can be written in any order. Anything over 1% must appear in order of the percentage, from highest to lowest.
The difference between alcohol and ethanol
Reading an ingredient list is confusing for many, especially when you read ingredients like cetearyl alcohol. At first glance cetearyl alcohol could easily be labelled an ingredient that is drying to the skin. But cetearyl alcohol is NOT ethanol. Ethanol is alcohol – an astringent ingredient that can be drying to the skin.
Ethanol kills microorganisms, hence why it is commonly used in hand sanitisers. Ethanol can be used in some skincare products, like serums to help reduce the tackiness of Vitamin C. It’s also used in products containing salicylic acid (many acne products and peels) to help dissolve the salicylic and also help drive it deeper into the skin. Modern chemistry now can dissolve salicylic acid without ethanol. Ethanol free acne skincare means less drying the skin and
less irritation. It also means we can prescribe more frequent applications to speed up results.
Ethanol INCI is generally listed as ethanol, alcohol and SD alcohol.
Back to cetearyl alcohol. Naturally derived from plants, cetearyl alcohol is a mixture of fatty alcohols that functions as a thickener. It is an emulsifier that is commonly used to thicken formulations, improve texture and stabilise ingredients. So, essentially, when you see “alcohol” following a name (like cetearyl), it is generally good for the skin, not bad. Unlike ethanol, it will not dry out the skin, nor create any irritation.
Is Hyaluronic Acid an acid?
Alpha- and beta-hydroxy acids help to exfoliate the skin, so hyaluronic acid (HA) will have the same action, right? Wrong. In fact, it is not actually an acid. Hyaluronic acid is a skin hydrator. Sometimes names are given to ingredients where the origin is unclear, and hyaluronic acid is an example of that.
Hyaluronic acid’s name is derived from hyalos, the Greek word for vitreous. HA is found in vitreous humor, synovial fluid and the umbilical cord. It was first discovered in 1934, by Karl Meyer and John W. Palmer at Columbia University (New York). They isolated HA from the vitreous humor of cattle eyes and measured many of its properties.
HA is found in the body. It is a natural lubricant for the soft tissue that support joints such as hips and knees, helping them to function smoothly. HA is sometimes injected into arthritic joints to ease pain and assist movement.
Over the past few decades, it has become the trusted “fountain of youth” ingredient in skincare. Due to hyaluronic acid’s anti-inflammatory, restorative and hydrating properties, one application of an HA serum can resolve a number of skin issues almost immediately. Helping to keep the skin functioning in a balanced state. It helps deliver active ingredients deeper into the skin. Hyaluronic acid is so trusted that we now formulate all Dermaenergy serums in a HA base.
This article first appeared in the November/December issue of Professional Beauty magazine. Download the issue here.
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