Bases In Lipstick and Mascara
The type of base used depends on where the product is supposed to be applied. For example, in lipsticks, about half the weight of the product is accounted for by a thick, insoluble mixture of waxes and castor bean oil that will not dissolve when a woman licks her lips or drinks a beverage. A lipstick base must balance the properties of the oil ingredients with those of wax. The oil in the lipstick makes it viscous (thick and sticky), so that the color clings to the lips. The waxes are thixotropic (becoming fluid only when stirred), so that the lipstick retains its shape and doesn't smear or melt in heat.
Other key ingredients of a lipstick base are slippery chemical compounds called esters, which are formed by reactions between alcohols and acids. Esters are added to make a lipstick shine and make the rather dry oil-and-wax mixture glide onto lips more smoothly.
Like lipstick, mascara relies on relatively heavy bases, such as paraffin and carnauba palm wax, not only to keep lash-darkening pigments stuck to the eyelashes through water and tears, but also to thicken and separate the lashes. On the other hand, eye shadow, blush, and other powdery products are bound together by lighter bases, often mineral oil, because they aren't constantly under assault by makeup-dissolving liquids.