Sodium Hydroxide (NaOH) is also referred to as lye or caustic soda. It is a sodium atom ionically bonded to a hydroxide ion.
Sodium hydroxide is known as a strong chemical base. When it’s combined with water, it has a pH of 14, which is pretty dang strong.
In fact, the alkalinity is so strong, it’s known as a corrosive. The word corrosive comes from the Latin verb corrodere, which means “to gnaw”. This is because with proteins like skin, hair and nails, sodium hydroxide will gnaw right through em’! Nom Nom Nom!
In Fight Club, Tyler Durden demonstrates sodium hydroxide’s corrosive ability by delivering a severe chemical burn! If you’re working with sodium hydroxide, know the safety precautions and if you value your eyeballs and skin make sure they’re protected!
When sodium hydroxide is combined with water it releases heat! This is called an exothermic reaction! NEVER mix sodium hydroxide with aluminum. In 2011, an aluminum tanker (Sawyer, Michigan) was mistakenly used to transport a sodium hydroxide solution. The chemical reaction caused an explosion and yielded hydrogen gas. KA-BOOM!
SO WHAT IS SODIUM HYDROXIDE DOING IN YOUR COSMETICS?
In HAIR RELAXER: it denatures proteins so curly hair becomes straight. At a pH of 14, the alkalinity in hair relaxer is so high, it permanently breaks the disulfide bonds that gives hair its shape. Hair straightened in this way can’t be curled again until replaced with new hair. The chemical process this undergoes is called lanthionization.Sandra Denton, aka Pepa from the 80’s duo Salt-n-Pepa revealed her asymmetrical hairdo happened by accident. Her sister burned the side of her head with hair relaxer!
In HAIR REMOVER: In products like Nair, it’s a key ingredients that removes hair, along with sodium thioglycolate, strontium sulfide, and calcium thioglycolate. In fact, it’s so good at breaking down hair, that sodium hydroxide is also found in Draino – where it breaks down the hair and bio-gunk that clogs the drain.
In BODY WASHES: and other cosmetic products sodium hydroxide acts as a PH adjuster, moving the pH along a scale to a desired value. Studies have shown that a skin’s natural pH averages at about 4.7. To keep cosmetic formulation mild, a formulator will try to keep a product as close to a skin’s natural pH as possible. If a product is too acidic, a formulator will put in tinsy amounts of sodium hydroxide (alkaline), to counter the acidity and tip the scale to the less acidic 4.7. If a formulation is too alkaline, then a formulator will put in an ingredient like triethanolamine (acidic) to bring it towards 4.7 acidity.