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Soap Explained

What Is Soap?


It’s a trickier and more complicated question than most people think. But then, a lot of things get complicated when there’s a difference between how we use words casually and what they officially mean.

Soap is one of those words that surprises a lot of people. Soap is soap, after all. It’s either a 4-oz rectangular bar in a certain aisle of the store or a gel-like substance in a bottle with a pump. Both of those examples might be true, but the greater likelihood is that what we’re calling soap is technically something else.

It’s Not a Detergent

Much of the confusion with the official definition occurs between true soap and synthetic cleansers – what the FDA calls “detergents.” True soap, or ordinary soap, is defined as the “combining of fats or oils with an alkali, such as lye.” Many of those bars on the shelves, and many of those bottles with a pump, aren’t soap at all, but a mix of synthetics, many of them included to offset the essential skin-stripping nature of detergents.

The FDA makes no distinction between soap made with vegetable fats and soap made with tallow. They make no attempt to define organic soap. There’s is a simple task. Even the regulation of soap falls to a different government agency, the Consumer Products Safety Commission. Still, it’s not just ingredients that determine whether a product falls under the regulatory definition of soap. There are two more variables to consider. Here’s a handy three-point definition:

1. Ingredients. To be regulated as soap, a product must be composed mainly of the “alkali salts of fatty acids,” meaning what you get when you combine fatty acids with lye.

2. How It Cleans. The “alkali salts of fatty acids” must be the only ingredient that provides cleaning action. If added synthetics play a part, the product is no longer soap, but a cosmetic.

3. Its Intended Use. To be regulated as soap, a product must be labeled and marketed only as soap. If its intention is to moisturize the skin, deodorize the skin, or make the skin smell nice, it’s no longer soap, but a cosmetic. If it’s intended to treat eczema or prevent disease by killing germs, it’s no longer soap. It’s officially a drug.

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