The proverbial bread in the polish sandwich, base and top coats help polish adhere to nails and prevents nails from chipping and breaking. The clear base coat is applied first to the natural nail to secure to the nail bed and act as an adhesive bed for the pigment to fasten. Top coat is then applied over the polish to seal in the color and protect it. But how are these top and base coats different than colored polish? And how do they help prevent chipping and breaking?
What it is — Base Coat: You can think of base coat as double-sided sticky tape. It binds effectively with the natural nail, then provides a layer on top that is receptive to polish and forms a tight bond with it when the polish is applied.
What it is — Top Coat: A clear layer of lacquer that is applied over dried colored polish to create a barrier surface to prevent against chipping and provide a high-gloss shine that dries in a short amount of time.
What’s in them? For base and top coats, (and polish) you need ingredients called “solvents” that act as transporters for other chemicals you want to function on the nail. These functional chemicals are dissolved into the solvents because they are not able to stand alone as a liquid. Chemists use special “volatile solvents” for lacquers, with volatile meaning they evaporate quickly. So lacquers need a mixture of volatile solvents to deliver other chemicals to the nails, and then evaporate away, leaving the functional chemicals behind to do their jobs. Common nail product solvents are ethyl and butyl acetate.
Base coats also have plasticizers, which are chemicals that introduce flexibility to a substance. This is important for base coats because you want a layer that will bend with the natural nail and not break. Base coats also need cellulose chemicals to create that double-sided sticky layer that adheres to both the natural nail and polish.
Top coats are characterized by their ability to dry quickly and create a high-gloss shine. Nitrocellulose contributes to this shine, but it comes at the expense of dry times. Top coats need one or more cellulose-based chemicals to get a correct shine, and they need plasticizers as well for flexibility. The thicker the viscosity of the top coat, the higher the shine, but the longer it will take to dry.
What makes them different than polish? The main difference between top and base coats and colored polish is the mixtures between the volatile solvents, cellulose chemicals, plasticizers, and pigments. When manufacturers are creating colored polish, they have to include pigments that can have an effect on other chemicals in the formula, and the functionality of the polish can be slightly affected. This is why clear top and base coats are excellent tools for ensuring long and durable polish wear, because they can focus on providing excellent adhesion, flexibility, and retention and are not compromised by pigments.