Occasionally at our sales events, someone will pick up a bar of our soap, look at the label, and then look curiously at me and ask, “Is your soap lye free?” Or something to that effect.
The short answer is yes. But, since the long answer would include something about the necessity of using lye in the manufacture of soap, why is lye not listed on soap labels?
It is not required to list lye in the ingredients because in saponification (see How Does Soap Clean?) all of the lye is converted into fatty acid salts, so there is no lye in the final product. In fact, listing ingredients for real soap is not required. But, when soap makers do choose to list ingredients, they may either list all the ingredients used in making the soap or the ingredients in the final product, which would simply be soap plus whatever colorants or fragrances were added.
Can soap be made without lye? That depends on what you are referring to when you say “soap”. Real soap is always made with lye because real soap is defined as a product whose nonvolatile matter is mostly made up of alkali salt of fatty acids, which is solely what causes the cleansing action, according to the Consumer Product Safety Commission. One way you can distinguish soap from a detergent when label reading is to look for natural oils, which are part of the main ingredients in soap.
Real soap is considered a gentle, safe, eco-friendly cleanser. But, real soap does not perform well in hard water, which contains higher amounts of calcium and magnesium ions. Ever heard of “soap scum”? That’s precipitate that occurs when soap interacts with hard water.
Synthetic detergents—or syndets—were designed to work in hard water. Syndet bars are soap (that’s a misnomer!) bars that do not require lye in their manufacture. Many detergents used to rely on phosphates, which performed well but were not good for the environment. Synthetic detergents have also typically had a more aggressive surfactant ability than real soap. And, they have better stain-removing capabilities.
Nowadays, however, more products with naturally-derived synthetic detergents are becoming available. These newer synthetic detergents can be gentle enough to use in baby products. In fact, while real soap has always been considered gentler, safer, and more eco-friendly, some good synthetic detergent options do exist.
Did you know that real soap is a great option for safely and gently cleaning your hands, face, and body, but it’s not the best choice for hair care? We’ll dive into that topic soon!
Want to try a safe, gentle, eco-friendly cleaning product like real soap? Visit AngelwoodSoapCompany.com and try a bar today!
Reference & Resources
Consumer Product Safety Commission. Soap Business Guidance. n.d. Available: https://www.cpsc.gov/Business--Manufacturing/Business-Education/Business-Guidance/Soap.
McLeod, Jodie. Soap vs. Detergent: What's the Difference? Savvy Natural Cleaning, n.d. Available: https://savvynaturalcleaning.com/soap-vs-detergent/.
Soap Queen. How to Label Cold Process Soap. Bramble Berry, 30 Nov 2011. Available: https://www.soapqueen.com/bath-and-body-tutorials/cold-process-soap/how-to-label-cold-process-soap/.
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