Understanding the melting behavior of solid emollients is crucial for cosmetic formulators aiming to tailor product texture and skin feel. Unlike common assumptions of a single melting point, many plant-based solid emollients melt gradually over a temperature range, impacting their sensory properties and application experience.
The Overlooked Importance of Emollient Melting Profiles
Emollients play a vital role in cosmetic formulations, shaping both texture and skin feel. By carefully selecting the right emollients, formulators can design a product’s sensory profile to match different application needs and consumer preferences. Key chemical properties—such as polarity, viscosity, and volatility—directly influence how a product feels on the skin, whether light and fast-absorbing, silky-smooth, or rich and nourishing. Solid emollients are used to deliver richness, structure, and body in creams, balms, and stick products. However, the role of an emollient’s melting profile—the transition from solid to liquid across a defined temperature range—remains less well understood.
Beyond the Melting Point: The Hidden Complexity of Solid Emollients
A common misconception in cosmetic formulation is that solid emollients, such as shea butter, have a single, sharp melting point—transitioning from solid to liquid at a specific temperature. It probably originates from the fact that you commonly find the melting point included as a parameter in product specifications. In these cases, the melting point is defined according to a specific analytical method and may vary between suppliers. However, this melting point does not help cosmetic formulators to understand the behaviour of the ingredient. In reality, plant-based solid emollients composed of triglycerides are complex mixtures of various molecules. As a result, they do not exhibit a distinct melting point but rather melt gradually over a range of temperatures.
The presence of a melting profile in solid plant-based emollients is a valuable property that cosmetic formulators can strategically utilize during product development. This melting behaviour can be effectively studied using Nuclear Magnetic Resonance (NMR), which allows for the quantification of solid content within a sample at specific temperatures. By plotting the solid fraction against temperature, formulators gain meaningful insight into how the emollient behaves both in its final format and during application. What is the texture and consistency of the emollient at room temperature? How does it transform upon contact with the skin?
The Impact of Melting Profiles on Sensory Experience
Let’s take two emollients as an example. LIPEX® IllipeSoft™ and LIPEX® SMP™ both have similar proportions of solid material at room temperature, approximately 55-60%. They are both hard and waxy and work well to deliver body and structure to sticks and rich emulsions. But as they are applied to the skin, they behave completely differently. LIPEX IllipeSoft melts slowly giving rise to a luxurious texture and long play time. At body temperature (35°C), it contains almost the same amount of solid content as at room temperature, meaning that the body temperature has a minimal effect on the melting. LIPEX SMP on the other hand, transforms completely in contact with body temperature, going from hard and waxy to fully melted. A skin care product using LIPEX SMP can give rise to a true wow effect as it enables the formulation to transform in texture during the application.
Solid Content Matters: Why Emollients with Similar Melting Profiles Can Feel Different
Slow melting emollients can also give rise to different types of skin feel. The amount of solid content at room temperature results in different hardness. Like LIPEX IllipeSoft, LIPEX® SheaSoft TR™ also has a slow-melting profile. But as it contains a lower amount of solids at room temperature, it is perceived as softer than LIPEX IllipeSoft, both in the jar and on the skin. Interestingly, slow-melting emollients that retain a high proportion of solid content at body temperature tend to create a noticeably drier skin feel. This is because the emollient remains partially solid upon application, rather than fully melting into a liquid. As a result, there is less of the oily or greasy residue typically associated with more fluid emollients.
The tactile experience is one of a more matte, dry-touch finish, which can be particularly desirable in products where a non-greasy afterfeel is preferred—such as in facial moisturizers, mattifying formulations, or products designed for oily or combination skin types.
Melting Profiles Unveiled: Choosing the Right Emollient for Texture and Skin Feel
Understanding the melting profiles of solid emollients is key to designing the desired sensory experience in cosmetic formulations. Slow-melting emollients that retain a high proportion of solid content at body temperature provide structure, a long “play time,” and a drier, matte finish—ideal for sticks, rich creams, mattifying moisturizers, or products for oily and combination skin. Fast-melting emollients, which fully liquefy upon skin contact, deliver a luxurious, silky texture and a “wow” effect during application, making them well-suited for rich emulsions, body butters, or products where a smooth feel is desired. By selecting emollients with the appropriate melting profile and solid content, formulators can precisely control texture, application experience, and afterfeel to meet specific product goals and consumer preferences.
