Washington Esthetician State Board Practice Exam

What category of emulsion is suntan lotion classified as?

1. Water-in-oil emulsion

2. Oil-in-water emulsion

3. A solid emulsion

4. A mixed emulsion

The correct answer is: Oil-in-water emulsion

Suntan lotion is classified as an oil-in-water emulsion because it typically contains a higher proportion of water compared to oil. In this type of emulsion, tiny droplets of oil are dispersed in a continuous water phase, which helps provide a lighter texture, making it easier to apply and absorb into the skin. This formulation is desirable in suntan lotions as it helps hydrate the skin while providing the benefits of the oils, such as moisturizing and enhancing the effectiveness of the sunscreen. The oil-in-water emulsion also facilitates a lightweight feel, which is preferred by many users to avoid the greasiness that can come from heavier oil-based products. In contrast, a water-in-oil emulsion would have a greater oil content, resulting in a thicker, greasier texture that is less common for suntan lotions aimed at easy application and comfortable wear during sun exposure. Solid emulsions are generally not used for sunscreens, as they are not practical for topical applications. Mixed emulsions, while possible, are not the standard classification for suntan lotions, which adheres primarily to the oil-in-water formulation for optimal performance and user preference.