Astringents, also referred as toners, are chemical compounds that contract the tissues. In skin care, astringents are used to tone the skin and make it firm by constricting the pores. Astringents create a protective layer between the underlying layers of the skin with the external elements. They are said to contain antioxidants that fight bacteria on the skin and help it to look clean and fresh. Excessive application of astringents can dry the skin. Witch hazel/ green tea is a natural astringent that is widely used.