Want to learn to distinguish a “soap” from a “detergent”? This is your guide to reading labels.

If muddling through the fine print is not your thing (no judgment, that’s why we’re here!), you can head to the Start with Soap Store to buy a true soap from us.

But if you want to learn to dissect product labels and choose your own soap, read on.

Go Straight to the Ingredients

To determine whether a product is a “soap” or “detergent,” go straight to the list of ingredients.

Pay no attention to anything else, because the word “soap” appears on the front of so many products that are actually detergents.

Soap Ingredients

Soap labeling is flexible—there is no required, standardized approach. Actually, a true soap need not list any ingredients, at all. But there are three common approaches.

Saponified oil

The word “saponified” tells you that a base was reacted with the stated oils to make soap.

In practice, this reads, “Saponified coconut oil,” or, “Saponified oil of coconut.” You will also see other oils, like sunflower seed oil, olive oil, palm oil, castor oil, etc.

Oils, water, base (what goes into the pot)

This approach tells you “what ingredients go into the pot” during the soapmaking process.

The ingredient list will include the type of oil or fat that is used, water, and either sodium hydroxide (for solid soap) or potassium hydroxide (for liquid soap).

In practice, this reads, “Coconut oil, water, sodium hydroxide (none remains after saponifying oils into soap and glycerin).” Again, you will also see other oils, and you will see potassium hydroxide instead of sodium hydroxide for liquid soaps.

This is the approach we use for Start with Soap labeling, because we want you to know exactly what goes into our soap.

Chemical names (what comes out of the pot)

This approach tells you “what comes out of the pot” after the soapmaking process is complete. The saponified oils are stated in terms of their chemical names.

Because these are chemical names, they are not as readily identifiable as other terms, but you can get the hang of this.

Let’s start with an example: “sodium cocoate.” This is the chemical name made from coconut oil and sodium hydroxide. “Sodium” tells us that sodium hydroxide was the base,” and “coco-” tells us that coconut oil was the acid.

Generalizing that example, the format is:

• “Sodium” or “potassium” (depending on whether sodium hydroxide or potassium hydroxide is used),

• Followed by a term that sounds like the oil or fat (e.g., “coco” for coconut, “oliv” for olive oil),

• Combined with the suffix -ate.

It tends to make more sense as you see more examples. These are all names for saponified oils or fats:

• “sodium olivate” (olive oil and sodium hydroxide)

• “potassium olivate” (olive oil and potassium hydroxide)

• “potassium cocoate” (coconut oil and potassium hydroxide)

• “sodium tallowate” (tallow and sodium hydroxide)

Again, when done properly, the sodium hydroxide or potassium hydroxide are consumed by the reaction and do not remain in the final product.

Detergent Ingredients

Detergent-based products will typically list a number of chemicals that are more challenging to read and understand. There are so many different detergent formulations that it’s difficult to generalize the ingredients you are likely to see.

However, there is one common detergent worth mentioning here. Sodium lauryl sulfate (or “SLS”) is a widely used synthetic surfactant that is a known irritant (to skin, eyes, etc.). Because it is a known irritant, it has fallen out of favor to some extent. Many products now claim to be “SLS free,” but in practice, these products are simply replacing SLS with other synthetic surfactants that have similar effects.

Other Ingredients

Just because a product is a true soap does not mean that it automatically passes muster. Watch out for other undesirable ingredients, like fragrance (more on the topic of fragrance here), preservatives, low-quality oils, etc.