Even though a person might wash her face on a regular basis, there can still be some instances where a beautifully done set of eye makeup can be marred due to the crease in the eyelid and the fact that oil will eventually cause the eye shadow used for a Smokey Eyes look to sit inside the eyelid's crease. A good way to prevent this from happening is to use a primer. An eyelid primer is like a base paint that's designed to keep the oil from the face from interfering with the eye shadow that's been applied to the eyes.