The oil in water system (also known as O/W) has a higher water phase ratio than the oil phase, and the oil is dispersed in the form of small droplets in water. Generally speaking, with high moisture content, the texture will be fresher and easier to push open. The water in oil system (also known as W/O) is exactly the opposite, with a higher proportion of oil phase than water phase, and water dispersed in the form of small droplets in the oil. Oil and fat have strong sealing properties, superior water locking and moisturizing properties, and relatively speaking, the texture will be more moisturizing and thick. In the microscopic world of cosmetic formulations, emulsifiers act as blenders, tightly combining previously immiscible oil and water to form a stable homogeneous system. The two major emulsification systems of O/W and W/O directly determine the skin feel, efficacy, and applicable scenarios of skincare products. Let's talk about the differences, advantages, and how to choose between these two emulsion systems.
Two basic types of emulsion systems
In cosmetics and personal care product formulations, the role of emulsifiers is to stabilize the fusion of oil and water phases. According to the different dispersed and continuous phases, emulsion systems are mainly divided into two categories:
Oil in Water (O/W): Disperse oil droplets in a continuous aqueous phase, simply put, water envelops oil. This kind of product usually has a fresh texture. For example, most of our daily moisturizing lotion and refreshing face cream belong to this type.
Water in oil (W/O): Water is dispersed in the oil phase, meaning that the oil is wrapped in water. Its texture is relatively mellow and moisturizing, with stronger sealing properties. Sunscreens and high moisturizing hand creams often use this system.
The essential difference between these two systems lies in the encapsulation relationship between oil and water, which directly affects the user experience and efficacy of the product. In the actual impulse formulation process, formulators usually choose the appropriate system type based on the target skin feel and stability requirements of the product.
Oil in water emulsifiers are widely used in cosmetic formulations, especially for daily care products that pursue a refreshing skin feel.
It has water as the continuous phase, and the oil phase is dispersed in the form of tiny droplets. This structure makes the product feel light and can be quickly absorbed by the skin after application, without a heavy and sticky feeling, giving people a moisturizing and refreshing experience.
In terms of formula, the oil in water system has many advantages. It can be well compatible with water-soluble active substances and moisturizers, such as hyaluronic acid, vitamin B5, etc., and can fully exert its moisturizing and soothing effects. Meanwhile, it has good tolerance to ionic environments, minimal viscosity changes during storage, and strong stability. Moreover, such products are easy to wash and have a clear skin, which is suitable for developing lightweight moisturizing products or daily care lotion.
For example, our daily moisturizing lotion, refreshing face cream, body milk, and most sunscreen spray rely on oil in water
Emulsifier to achieve the experience of water sensitive skin care.
Water in oil emulsifiers take a moisturizing and long-lasting route, becoming the preferred choice for protective and high-performance products due to their excellent sealing properties and long-lasting moisturizing power.
It takes oil as the continuous phase, and water droplets are enveloped in the oil phase. This structure can form a protective oil film on the surface of the skin, effectively reducing water evaporation and resisting external environmental stimuli to the skin, such as dry air, cold winds, etc. On the skin feel, O/W will be much fresher than it, W/O tends to be softer and thicker, and may even have a slight oiliness.
The advantages of the water in oil system are also evident. Its long-lasting water locking and protective power is very strong, especially suitable for use in dry seasons or dry skin. For example, high moisturizing face cream and repair hand cream in winter, they all rely on it to achieve deep water locking. And it has excellent water resistance, and its structure is not easily damaged when in contact with water, so it is commonly used in sunscreen, waterproof makeup base and other products, which can ensure the durability of the effect. In addition, it can also carry oil soluble active ingredients and play a role in repair, antioxidant and other functions.
Sunscreen, high moisture hand cream, cold cream, autumn and winter repair face cream, and some functional products that need strong sealing are inseparable from the water in oil emulsifier's water locking function.
Comprehensive comparison
| Comparison Dimensions | Oil-in-Water (O/W) | Water-in-O (W/O) |
| Continuous Phase / Dispersed Phase | Aqueous phase is continuous, oil phase is dispersed | Oil phase is continuous, aqueous phase is dispersed |
| Skin Texture | Lightweight, refreshing, easily absorbed | Rich, moisturizing, strong occlusive properties |
| Core Efficacy | Hydrating, refreshing moisturizing | Long-lasting water retention, protection, moisturizing |
| Suitable Scenarios | Daily care (lotion, light cream), oily or combination skin. | Dry seasons, dry skin, protective products (sunscreen, highly moisturizing hand cream). |
| Water-Soluble Ingredient Compatibility | Good | Poor |
| Water Resistance | Poor | Good |
Balance skin texture and functionality
In actual formula design, choosing between oil in water or water in oil system is actually balancing skin feel and functionality:
If you want a "light, transparent and fast" skin feel, such as moisturizing lotion for young oily skin, or skin care products in spring and summer, oil in water system is a good choice, which can not only moisturize but also avoid greasy skin
If you pay more attention to the "moist and lasting" effect, such as the high moisturizing face cream in autumn and winter, and the waterproof sunscreen, the water in oil system can better meet the needs of long-term water locking.
Nowadays, many high-end skincare brands are also trying to integrate the advantages of two systems, using multi-layer emulsification, biphasic emulsification and other technologies to make their products both refreshing and moisturizing with oil in water, achieving a compound skin feeling that is both refreshing and moisturizing.
In summary
From daily refreshing lotion to winter high moisturizing face cream, from waterproof sunscreen to hand care cream, the selection of emulsification system is the key to the differentiation of cosmetics. The lightness of oil in water and the richness of water in oil are not necessarily good or bad, only whether they are suitable for product positioning and target audience.
With the continuous advancement of emulsification technology, formulators can find a better balance between stability, skin feel, and efficacy by adjusting the HLB value, molecular structure, and processing technology of emulsifiers. For consumers, understanding the differences between these two emulsification systems can also enable them to more accurately choose products that are suitable for their skin type and needs. After all, in the microscopic world of water and oil, there are secrets to the skin feel and efficacy of skincare products.
Yichang Mingya New Material Technology Co., Ltd.
