What pH is Soap?
Soap typically has a pH range of 9-10, although this can vary depending on the specific ingredients and manufacturing process. Many sources confirm this alkaline nature.
The pH scale measures how acidic or alkaline (basic) a substance is. A pH of 7 is neutral. Values below 7 are acidic, while values above 7 are alkaline. Soap's alkalinity is a key characteristic resulting from the saponification process, where fats or oils react with a strong alkali (like lye) to form soap.
pH Ranges in Different Soaps:
- Most Soaps: 9-10 (Multiple studies and sources confirm this common range).
- Castile Soap: 9-11.5 (This type of soap often exhibits higher alkalinity).
- Handmade Soaps: The pH can vary widely depending on the oil and fat composition, and curing time. Some handmade soaps can have a pH as low as 6.5.
Importance of Soap pH:
While soap's alkalinity is often cited as a reason for dryness and skin irritation, the effect of soap pH on the skin is a complex issue and is not solely dependent on the soap's pH alone. While it's true that extremely high pH levels can be harsh on skin, the formulation and other ingredients play a critical role. Neutral or low pH soaps are not necessarily gentler.
Measuring Soap pH:
pH testing is done on liquid soap, not solid bars. Wetting a solid soap bar and testing it on a pH strip may give inaccurate readings.
References Supporting the Answer:
- Multiple studies and online forums: Consistently report a pH range of 9-10 for most commercially available soaps.
- Botanie Soap Blog: States that the pH of natural soap (plant-based oils) is typically between 8 and 10. https://botaniesoap.com/blogs/product-faq/ph-of-soap
- Dr. Bronner's: Reports a pH of 8.7-9.9 for their Pure-Castile Liquid Soap. https://www.lisabronner.com/skin-health-ph-and-dr-bronners-soap/
- Study on Bathing Soaps and Shampoos: Confirms the general pH range of soaps. https://pmc.ncbi.nlm.nih.gov/articles/PMC4171909/
