Nail Polish: Chemicals on nails!

Introduction

Nail polish is a type of lacquer used on fingernails and toenails, mainly by women. Most nail lacquers are non-toxic. People want brands of nail polish that are easy to apply, dry quickly, glossy looking, and can last for a long time without chipping. Since it has to be strong, flexible, and resist chipping and peeling, it contains a number of chemicals. Some of the popular nail polish brands are Maybelline, AVON, Revlon and OPI.

Origins

Nail polish was used in various forms from the beginnings of civilization. Wealthy people in ancient China used a mixture of beeswax, egg whites, gelatin, Arabic gum and dyes to paint their fingernails red, black, gold, or silver. Egyptians paint their fingers with natural substances such as henna powder, a reddish powder made from dried leaves of the henna bush. Egyptians used nail colour to signify social order. Red is used by the highest ranks whereas women of lower ranks were permitted to apply only pale hues. By the turn of the ninth century, nails were tinted with scented red oils and polished. During the late nineteenth century in Europe and the United States, people started to manicure their nails. Women polished their nails rather than painting them. Coloured nail paint was developed when car paint was invented. It has a similar composition to that of car paint.

Compositions

Nitrocellulose

A basic clear nail polish could be made from nitrocellulose compound dissolved in butyl acetate (C₆H₁₂O₂) or ethyl acetate (C₄H₈O₂) . Nitrocellulose is a flammable and explosive ingredient used in making dynamite. It is naturally occurring. It is a liquid mixed with tiny, near-microscopic cotton pieces. Ethyl acetate is used as a solvent in oil-based lacquers and chemical processes. Nail polish turns from a liquid to a solid when this evaporates. It has a very low boiling point and it is commonly used in perfumes, paints, and wine. The nitrocellulose forms a shiny film as the acetate solvent evaporates. However, most nail polishes contain an extensive list of ingredients. 

The chemical composition of nail polish and the function of each of the ingredients are as shown below: 

• Solvents - Examples of solvents include ethyl acetate, butyl acetate and alcohol. 

  

  Ethyl acetate

  

  Butyl acetate

• Film Formers - Nitrocellulose acts as a film forming agent. It is also a main ingredients in most nail polishes. Film formers are chemicals that form the smooth surface on a coat of nail polish.

• Resins - An example of polymer used as a resin in nail polish is tosylamide-formaldehyde resin, which is an adhesive polymer. Resin makes sure the film adhere to the nail’s surface. It is an ingredient that adds depth, gloss and hardness to the film of a nail polish.

• Plasticizers - Plasticizers make the polish flexible after drying and reduce the chance that it will crack by linking between polymer chains. Camphor (C₁₀H₁₆O) is a common plasticizer.

• Pigments - Pigments are chemicals that add colours to the nail polish. Common pigments used include iron oxides and other colourants.

• Pearls - Nail polish that has a glittery effect contains pearlescent minerals, such as titanium dioxide (TiO₂) . Some nail polishes may contain bits of plastic glitter or other additives that produce a special effect.

• Thickening agents - Stearalkonium hectorite is used to keep the other ingredients from separating. It is also used to make the nail polish easier to apply.

• Ultraviolet filters - Some nail polishes contain ultraviolet filters, such as benzophenone-1 (C₁₃H₁₀O), which is used to resist colour changes when exposed to sunlight or other forms of ultraviolet lights.

  

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  However, after knowing so much confusing chemical names found on the ingredient list of your favorite nail polish, it's vital to identify which of these chemicals may actually be dangerous to us especially our body! Here, there are three main culprits found in many nail polishes that are formaldehyde (CH₂O), toluene (C₇H₈), and dibutyl phthalate (DBP)  (C₁₆H₂₂O₄). These toxic chemicals are known as the "Toxic Trio", or "Big 3" which exists in the nail polish. So, what are they and how they cause severe effect to us? 

• Formaldehyde - A chemical that is a component in plywood and particleboard, and is often used as a preservative, sterilizer, and embalmer. This chemical is added to nail polishes which is commonly known as "nail hardeners." Formaldehyde has also been considered as a carcinogen, linked to nasal and lung cancers.

  

  Formaldehyde

• Dibutyl Phthalate (DBP) -  It is added to nail polish to make it more flexible and less prone to cracks, chips and other annoyances.

  

  Dibutyl Phthalate

• Toluene - It is used to keep nail polish smooth and even when applied. This chemical  affects the nervous system with symptoms that include dizziness, headaches, nausea, and eye irritation. Toluene has also been linked to birth defects and developmental problems in children whose mothers were exposed to the chemical during pregnancy.

  

  Toulene

A kindly reminder to girls! Choosing a well-ventilated spot when visiting a nail salon and check the label of your polishes to see if they are "Big 3" free to minimize your risks from getting a poor nail polish. However, toluene, formaldehyde and dibutyl phthalate (DBP) are found rarely in nail polish now or found in low concentrations because of its toxicity.

Manufacturing process

Early nail polishes used soluble dyes. Today, the product contains pigments of one type or another. The choice of pigment to be used and its ability to mix well with the solvent and other ingredients is important in order to produce a good quality product. The modern manufacturing process is a very sophisticated operation utilizing highly skilled workers and advanced machinery. Consumers expect a nail polish to apply smoothly and easily and to be resistant to chipping and peeling.

1.   First of all, the colour pigments are mixed with nitrocellulose and plasticizers using a "two-roll" differential speed mill. The mill grinds the colour pigments between a pair of rollers that are able to work with increasing speed to produce fine dispersion of the colour.

2.   When the mixture is fully milled, it is removed from the mill in sheet form and then broken up into small chips for mixing with the solvent. The pigment mass is mixed with solvent in a stainless steel kettle. The kettle has a water-jacket so that the mixture can be cooled by circulating cold water around the outside of the kettle. 

Caution: Stainless steel is used for the process because the nitrocellulose is extremely reactive in the presence of iron. This step has to be carried out in an area designed to control the hazards of fire and explosion. Most factories nowadays perform this step in an area with walls that will close if an alarm rang or the ceilings will safely blow off in the event of explosion without endangering the rest of the structure.

3.   The materials that are mixed in a computerized, closed kettle are cooled slightly before the addition of perfumes or moisturizers. 

4.   Lastly, the mixture is pumped into a smaller drum and trucked to a production line. The finished nail polish is pumped into explosion proof pumps, and then into smaller bottles that are suitable for the market.

In conclusion, there are multiple choices of nail polishes available in the market nowadays. Therefore, it is necessary for the consumers to choose wisely as some of the nail polishes contain chemicals that are harmful to us. Although beauty is important, especially for women, we need to care of our health too.