Washington Esthetician State Board Practice Exam

What is one defining characteristic of oil-in-water emulsions?

1. They are stable for longer periods

2. The oil droplets are dispersed in water

3. They have a heavier texture

4. They consist primarily of solid ingredients

The correct answer is: The oil droplets are dispersed in water

Oil-in-water emulsions are defined by the characteristic that oil droplets are dispersed in a continuous phase of water. This structure allows for a lighter, more fluid texture and makes the products feel less greasy on the skin compared to water-in-oil emulsions. Because the oil is suspended in water, the result is typically a product that is more easily absorbed and less occlusive, which is often desirable in skin care, especially for those with oily or combination skin types. The formulation generally incorporates emulsifiers that stabilize the mixture, ensuring that the oil and water do not separate. The other characteristics mentioned in the options do not represent the defining feature of oil-in-water emulsions; for example, they may not necessarily be stable for longer periods, can vary in texture, and do not consist primarily of solid ingredients. The prominence of oil droplets dispersed in water is what makes this type of emulsion unique and beneficial for a variety of cosmetic formulations.