For decades, nail professionals and consumers have been told by product manufacturers that pigments in nail polish cause natural nails to turn yellow. Influencers regurgitated this position, and the nail industry perpetuated the myth. This article will debunk the myth and provide possible reasons why natural nails can turn yellow.
You can peruse past trade and mass publications in the nail industry, and you will find articles about why natural nails are yellow say it is because of the pigments in nail polish, lacquer or varnish. The terms polish, lacquer and varnish are used interchangeably because they denote the same product—a colored coating applied on top of the nail plate—with or without the use of a base or top coat.
As you know, a base coat is the first layer applied on the nail plate, followed by the color coat, with the last layer being the top coat. When nail polish was introduced to the beauty industry in the early 20th century, all nail polish coatings consisted of nitrocellulose as their primary film former, combined with other ingredients and carrier solvents. We will refer to these products as “traditional nail polish.” Polish is the generic name used by both the public and beauty professionals for the multilayered dried coating on the nail plate.
When the traditional polish is removed with any polish remover, most often the natural nails are discolored to a yellow or orangey color. It is as if turmeric or carrot juice was rubbed on the nails. The only quick remedy the nail technician uses to restore the nail to its natural color is to remove a thin layer of the nail plate using a buffing block, which could lead to nail damage such as the over-thinning of nails, which compromises the nail plate’s integrity.
Nail schools, nail polish manufacturers, brand consultants and influencers still ascribe the yellow discoloration to the pigments in nail polish. Their prescribed preventative measure is to always use a base coat. And yet, even when wearing a base coat under the color, natural nails turn yellow.
If pigments were to migrate from the polish through the base coat, and to the nail plate, the nail plate would take on the color of the polish itself. That is, when one wears a blue polish, the nails would turn blue, and when one wears a red polish, the nails would turn red. But, the nails do not take on the polish’s color; they always turn yellow. Therefore, the culprit could not be the pigments but something else in the polish and base coat.
So, what is the real cause of natural nails turning yellow with traditional nail polish? I inspected the ingredient lists of numerous traditional polish brands, along with their base coats, and found one commonality in these products: They all have nitrocellulose as their primary film former. The true culprit is nitrocellulose.
Figure 1. Conversion of cellulose to nitrocellulose
As a chemist, I know that nitrocellulose comes from cotton or wood pulp that is reacted with concentrated nitric acid and sulfuric acid. Assisted by sulfuric acid, the nitro group displaces the hydroxyl groups in cellulose and liberates water (H2O) to form nitrocellulose (See Figure 1). The nitrocellulose is washed several times with water to remove the sulfuric acid and excess nitric acid. To remove the water, the product is washed with isopropyl or ethyl alcohol. The water mixes with the alcohol while the nitrocellulose, which is insoluble in alcohol, remains when the mixture goes through the washing and filtration steps.
Nitrocellulose is an excellent film-former for nail polish because it is soluble in organic solvents such as acetone, ethyl and butyl acetate, and has relatively good adhesion to the nail plate. However, it has its drawbacks. Nitrocellulose is stored and sold wet with alcohol because it may explode if dried and exposed to heat, flame, friction, or shock. Wet nitrocellulose is classified as a flammable solid in shipping.
When water is present (it is not easy to remove it completely), some decomposition occurs to liberate the nitro group into nitric acid. Nitric acid is a small molecule that can permeate through the polish on the nail and is a strong oxidizer that can oxidize some organic compounds. Certain pigments and proteins are examples of oxidizable substances. One such protein is keratin, so it is important to know that the natural nail plate is composed mostly of this protein. The oxidation products of organic compounds are usually yellow to start, and then they turn brown. Thus, when nitric acid (the decomposition product present in nitrocellulose) reacts with the nail plate (the protein keratin), it results in the yellowing of natural nails. This is also the reason certain traditional polish colors that are light pink turn brown, even when kept in the dark. Both the base and color coats of traditional polishes contain nitrocellulose. Therefore, unless water is completely excluded from them, applying a base coat under a traditional color coat will not prevent the yellowing of natural nails. One way to prevent yellowing is to use a nail polish system that is completely nitrocellulose-free.
So, why then does the myth continue? Could it be because the nail schools, in educating their students, rely on the information from the manufacturers? It certainly stands to reason that trade and mass publications also trust the education provided by nail polish brands. And we see that brand consultants and influencers who depend on these brand owners’ sponsorships also often convey what they have been told as if it were gospel. Could it then be that brand owners do not feel that it benefits them to be transparent about this issue? With the scientists and chemists now involved in the nail industry, it is hard to fathom why today, pigments are still blamed for yellow natural nails, just as they were decades ago. The perpetuation of this myth parallels the story of “The Emperor Has No Clothes”!
In the end, empowered self-education is what is needed to finally put this myth to bed. You can do your part by demanding absolute transparency coupled with responsible product formulation. Making healthier brand decisions will allow you to make yellow nails (from products) a thing of the past.
About the Author
Vivian Valenty, Ph.D., is the founder and president of VB Cosmetics, the creator and manufacturer of Dazzle Dry. She is also a member of Nailpro's 2022 advisory board. She obtained her doctorate in chemistry from Penn State University, and for the past 33 years, has been creating products for the professional nail industry.