Resins and plasticizers are added to the nitrocellulose in the nail polish -- to add flexibility and resistance to soap and water. Older versions of nail polish used nylon to achieve this effect. Although all nail polish needs this flexibility and resistance, there is no one resin or plasticizer that is universally used; instead manufacturers use combinations of amyl and butyl stearate, castor oil, glycerol, fatty acids and acetic acids.
After nitrocellulose and resins and plasticizers are combined, the next ingredient to add to the mix are coloring pigments held together by solvents. While early nail polish contained soluble dyes, today's products are colored with pigments. The solvent must evaporate after the polish is applied to nails. Coloring is added in a two-roll differential speed mill in order to grind the pigment as well make sure that all ingredients are evenly distributed throughout the polish.
How does all of this chemistry apply to your use of nail polish? A basic knowledge of the chemical components of nail polish can help your nail polish last longer and save you some money in the long run. For example, have you ever thought about why you shake a bottle of nail polish before painting your nails? Since nail polish is a suspension product, meaning that colors can only be held together for a short time, shaking the bottle before use will help to restore settled particles to the suspension. An old bottle of polish will have too many settled color particles that will be difficult to restore to the suspension and reconstitute into the solvent. Additionally, refrigerating nail polish will slow down discoloration as a bottle of nail polish ages. Refrigeration will reduce the evaporation of solvents and will prevent pigments from caking together. But be sure to keep the bottles upright; if a bottle of nail polish rests on its side, it can be more difficult to shake the pigments back together.
While a fresh coat of nail polish can top off the perfect outfit, it can also contribute to overall nail health. On the next page, we'll take a look at nail polish and nail health.