An eyeshadow base, also known as an eyeshadow primer, is a type of cosmetic product that is applied to the eyelids before eyeshadow. It generally comes in a cream or powder form, and is used to create a smooth canvas on the eyelids onto which eyeshadow is applied. Eyeshadow base has other uses as well, and may be able to be used underneath the eyes to hide dark circles, conceal imperfections, or as a highlighter to brighten the eyes.
When selecting an eyeshadow base, it is important to consider how it will be used. Most eyeshadow bases are matte, though some may have a bit of shine to them. Keep this in mind if the eyeshadow base will be used as a concealer, because then a matte version will generally be preferable. To use the eyeshadow primer as a highlighter, however, one might prefer for it to be a little glossier. When using this product as a highlighter, it is generally a good idea to apply it to the inner corners of the eye, as well as just under the brow bone; this will make eyes look brighter and more awake.
The primary purpose for using an eyeshadow base, however, is to allow the eyeshadow to adhere to the eyelids better, and to last all day without wearing down. It can also help to make creases in the eyes appear less noticeable. People with oily skin in particular often find that using a primer on their eyes before applying eye makeup is a good way to prevent the skin from becoming oily and the makeup from wearing off.
As when one is selecting a concealer or foundation for the rest of the face, it is a good idea to choose an eyeshadow base that is close to one's natural skin tone. In this case, it is acceptable if it is slightly darker than the skin on the eyes, because the eyelids tend to be quite pale, and the eyeshadow will cover most of the base anyway. Many cosmetics retailers will offer samples or allow customers to try out the products at the store before making a purchase.
When applying base for eyeshadow, use a makeup sponge or brush, and apply an even layer over the entire eyelid. Also apply to dark circles under the eyes, as well as to the brow bone and corners of the eyes if necessary. Then, simply apply eye makeup as usual, and it will look great all day.