Testers looked at how well the soaps lathered in limited amounts of water; how easily they rinsed off; and how clean and dry the skin was after washing. Four testers—with varying skin and hair types—used each soap in fresh water and salt water. The body wipe test products were used according to manufacturer directions. Testers also shampooed their hair with the soaps marketed as multi-purpose products (hair and body) in fresh and salt water.
In addition to the products’ performance, we tested each soap’s pH level using a common pH test kit. The pH value is a measurement of a substance’s acidity and alkalinity. The pH scale ranges from 0 to 14, with pH neutral at 7. On the acidic side: Lemon juice is 2, and vinegar is 3. Distilled water is a neutral 7. Moving into the alkaline or base area, baking soda measures just above 8 and ammonia is a 12. Lye would be around 14.
Most soaps and shampoos have a pH level of 7 to 10. The stronger and harsher the soap, the higher the pH level. Human skin and hair has an average pH level of 5, so even a pH neutral 7 product may feel like it dries out the skin.
We first tested each product undiluted and then re-tested them mixed with equal amounts of tap water, which had a measured pH of 6. The results are listed in the accompanying Value Guide. The entire field showed pH values of 5 or 6, with the exception of Campsuds Concentrated (7) and both Dr. Bronner’s Castile Soaps (8), which are highly concentrated.
Testers also noted price per ounce, packaging (with a preference for soaps available in 8 ounces or more), and subjective data such as smell and texture.