How Soap Works


Lye and vegetable oil. That’s soap. Created by Arabic chemists in the 7th century, the basic formula of modern soap has remained relatively constant. People can add different hydrators, antibacterial agents or fragrances, but the lye-oil combo is what helps remove the “ick,” both visible and microscopic, from our hands, body, and face. 

By itself, lye (or Sodium Hydroxide) is extremely harsh on the skin, but when combined with the right amount of oil and left to cure, these ingredients create the perfect mixture of fatty acid carboxylate and glycerin (nerd speak for soap). Our Handcrafted Soaps and Castile Body Washes use a combination of Vegetable Oils (Safflower, Sunflower, Coconut Oils) and lye to get just the right product.  

So how does soap work? Technically, water does the manual labor of removing unwanted matter. The soap allows your faucet to do this by trapping each molecule of dirt, grease, or foreign invader in a sphere called a micelle. Water can then carry that micelle straight down the drain. Questions on Micellar Water?  Click HERE for info on that.

Now let’s get super nerdy. Why do we need the micelle, you ask? For the same reason your oil and vinegar salad dressing just won’t combine - polar and nonpolar don’t mix. Oil is a nonpolar substance while vinegar is a polar substance, which creates those visible layers of dressing. But when it comes to handwashing, water is a polar molecule and the “ick” is nonpolar. Water therefore can’t just grab onto those pesky infectious particles. That’s where soap comes in. Soap takes advantage of this chemical magic because soap molecules are made up of both polar heads and nonpolar tails. The nonpolar tails rush to grab onto the nonpolar “ick” while the polar heads combine together in a sphere around the particle (the micelle). The micelle keeps the unwanted matter safely confined while water attaches to the polar head and washes our troubles away.

Graphic used with permission of Jonathan Corum of the New York Times

If you’ve followed me this far, it makes sense why soap is a powerful means to rid your hands of the coronavirus. The coronavirus is a squiggle of genetic material encapsulated in a non-polar lipid membrane. It takes our superhero soap to break open the membrane and trap the viral particles in a micelle so water can get it off our body!

So, now you know why you keep hearing about it on the news. Hand washing with soap and water really is advanced public health work. And you have some science to back up those twenty seconds we give ourselves at the sink. 

Leave a comment