As of 2014, most mascaras are made of many ingredients, including carbon black or iron oxide pigment, a polymer, preservatives, nylon, silk fibers and thickening waxes or oils. Carbon black and iron oxide are used to darken lashes, while nylon, silk fibers, thickening waxes and oils are used as bulking agents to give lashes a fuller appearance.
Some other bulking agents used in mascara include lanolin, mineral oil, paraffin, petrolatum, castor oil, carnauba wax and candelilla wax. Mascara also comes in two basic formulas: those that do not contain water and those that contain an emulsion of water and oil. Mascaras that contain an emulsion of water and oil are typically easier to remove, which causes less damage to eyelashes. Mascaras that do not contain water are typically water resistant, which prevents it from smudging or flaking during wear.
Before modern safety protocols were established, many of the ingredients in mascara caused blindness in users. As of 2014, ingredients that are used in mascara must be limited to those that are safe for use around the eyes. However, some mascaras include thimerosal, an ingredient that is used as a preservative in some mascaras, causes conjunctivitis and rashes on the eyelids. Nylon and silk powder can often cause adverse effects as well. Nylon irritates sensitive eyes, while silk powder may cause severe allergic reactions.