Usually, cleansers with an alkaline pH are not as well tolerated as cleansers with a neutral or acid pH. pH 7.0 is neutral (a 0.5 shift in any direction is still considered neutral). A pH higher than 7.5 is alkaline. A pH lower than 6.5 is acid. The pH of the skin is 5.5. This acid pH helps protect the skin, and is called "acid mantle". Cleansers with a neutral or acid pH do not disrupt this acid mantle like alkaline cleansers do.
Cleanser Types is a simple ebook designed to give you information on how to maintain your face skin clean.
