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Comparatively Speaking: Cushion vs. Playtime
By: Anthony J. O'Lenick, Jr., Siltech LLC
Posted: June 30, 2009
The way in which oil phases interact with the skin is an important part of what is called cosmetic elegance. Oils placed on the skin generally are rubbed into the skin. This rubbing results in the spreading out of the oil. How the oil spreads and the amount of time it takes to spread are respectively referred to as cushion and playtime.
Think of a drop of honey applied to the back of the hand. Rubbing it with a finger results in spreading out of the honey. During the rub out, a film is formed between the finger and the back of the hand. The thickness of this film is generally what is referred to as cushion.
Honey has a good amount of cushion but ingredients like isopropyl myristate have little cushion. Cushion is related to the viscosity of the liquid, the volatility of the liquid, the surface tension of the liquid, and the tendency of the liquid to be absorbed into the skin. Cushion is an important cosmetic property of oils.
Cushion does not last forever, and the length of time it takes for the cushion to disappear is referred to as playtime. Similar to cushion, playtime is dependent upon a variety of factors intrinsic to the oil and how it interacts with the skin.
Generally, the cushion and the playtime are intrinsic properties of the molecule, where manipulation of the properties require molecular changes of the oil. Recently, it was found that the inclusion of minor amounts of surface-active materials to the oil can result in a change to the cushion, the playtime or both.