What is the difference between soap and detergent?Updated a year ago
Sal Suds Biodegradable Cleaner* is a mild detergent, and the Castile and Organic Sugar Soap are soaps. The difference between soaps and detergents is that soaps are “the salt of a fatty acid”, which means they're made in a one-step reaction directly from oils--organic plant oils in our case (coconut, palm kernel, olive, hemp seed, and jojoba). Detergents require a more complicated reaction which in Sal Suds’ case, still starts with coconut oil but requires synthesis in a laboratory. The result is that the detergent molecule is much more sturdy and is not impacted by hard water. All of our soaps and detergent are excellent cleaning agents, scented with pure essential oil, and readily biodegradable, but the soaps are more nourishing for skin, and Sal Suds better in hard water and in grease fighting.
What they have in common:
- Soap and detergent are both surfactants.
- Surfactants break surface tension, allowing water to penetrate more fully into surfaces.
- Surfactants connect oil to water, two substances which otherwise repel one another. This is why you can’t just rinse oil off your hands. The water runs over the oil like it’s just not there. Surfactants act like Velcro between them.
- Surfactants form micelles around oil. Micelles are spheres of surfactant molecules with oil tucked inside.
Now for the differences: Soap has been made for millennia—one of humanity's oldest chemical reactions. It is one-step removed from nature, made by a beautifully efficient single reaction of combining oil (coconut, palm kernel, olive, jojoba & hemp for our Castile) with a strong alkali such as sodium or potassium hydroxide (the first also known as lye). Out of this combo, you get soap, glycerin, and water. Bam! No leftovers. No waste. Beautiful.
Detergents are more complex, multi-stepped, and must be synthesized in a controlled setting like a laboratory. They were developed during the World Wars when the plant oils needed for soap were scarce. They can start with botanical substances (such as coconut oil for our Sal Suds) or with petroleum derivatives. Detergents perform better in hard water, as they are a more stable molecule that doesn't dance with the minerals that make water hard. The uses and structures of detergents are vast and wide. It is really quite impossible to make other broad generalizations about detergents.
Sal Suds is a detergent which is like a soap in that they are both surfactants. Surfactants, whether soap or detergent, are able to grab hold of all manner of grime and debris and wash it away. It is common in everyday speaking for someone to call all substances that clean a "soap." However, from a chemistry standpoint, soaps are a simpler substance made from a reaction between a fat or oil and an alkali, and detergents are more complex. Our Castile Soap is a soap and Sal Suds is a detergent. Sal Suds are a fantastic way to clean dishes.
*Sal Suds cleaner shows >60% biodegradation after 28 days per ISO 14593.