“Combining materials that are not easily compatible is a challenge in any industry but when the end result is defined by its sensory, aesthetic, performance and application capabilities, it is particularly important,” said Belinda Carli, Director of the Institute of Personal Care Science.
As a large proportion of lotions and creams in the beauty and cosmetics sector are emulsions - formed when two fluids that usually don’t mix together are mixed - evolving methods and investing ongoing R&D that analyses these fluid properties is required to ensure formulations are consistent, productive and stable.
“Emulsions are one of the most important product forms in our industry – they enable lipids and a variety of actives to be delivered to the skin with water present so the end product spreads easily and is aesthetically pleasing compared to putting straight oil on the skin,” emphasised Carli.
“They can also be easily manipulated into milk or lotion and rich, viscous creams for consumers. Emulsions include your serums, lotions, creams, butters and even hair conditioners and many forms of crème based hair treatment products!” noted Carli.
Within cosmetics formulations, brands require emulsions that remain stable for a long enough time, as it is essential to overcome the interfacial tension between the two phases.
“Emulsions are always going to be important in any market – but with the extra focus on ‘sensory’ formulators need to get creative with product forms and playful textures or sensory delights,” added Carli.
“This can be done easily by manipulating your emulsion to provide unexpected, transforming or even playful textures.”
Carli went on to highlight the importance of keeping costs competitive: “We’re seeing the use of polymeric emulsifiers and or the creation of HIP emulsions or PIT emulsions where you can enhance the sensory/stability aspects through clever formulation and production techniques.”
The use of polymeric emulsifiers is being used to create gel-cremes as “these still enable an emulsion to form but instead of using waxy emulsifiers, polymeric emulsifiers enable a lighter ‘gel’ structure to hold the lipid in the emulsion. This enables a lighter feel to the skin and even some playful textures to be created (bounce back, gelee) etc”, said Carli.
High Internal Phase (HIP) emulsions are also growing in popularity. “These need particular materials to be created, but the big bonus with these product forms is that they have an external lipid phase but still contain a significant proportion of water (often around 90%),” added Carli.
"These keep the product cheap and feeling light on application but with the external lipid phase, a fine/thin lipid film is applied to the skin to help provide effective protection against trans-epidermal water loss.”
HIP emulsions are successful in creating a sensory feel. “They provide a ‘water break’ sensory feel – a feeling of water bursting onto the skin on application, which is great to tie in with the popularity of hydration claims of so many product launches,” added Carli. “The water break doesn’t actually provide extra hydration but it gives the perception that it does to consumers.”
Another leading emulsion in the marketplace is Phase Inversion Temperature (PIT) emulsions, which “enable faster processing times and finer emulsion droplet size for enhanced aesthetic appearance, skin feel and even better stability (shelf life). It uses the concept of an inverse emulsion, typically water/oil being formed first, and then extra water added to ‘flip’ the emulsion to become oil/water using cold water”.
Selecting these emulsions can ensure stable, aesthetically and sensory pleasing products on applications. The adoption of PIT or HIP emulsions may help manufacturers to achieve long-term emulsion stability.
In addition to creating cost-savings, formulations should also maximise the reduction of processing times, temperatures and cooling.
Belinda Carli will be presenting at in-cosmetics Asia 2016 between 8th-10th November on HIP emulsions (10th November 12:45pm – 1:45pm) and PIT emulsion ( 9th November 4:15pm – 5:15pm), both at the Formulations Lab.