Thread: Very Hard Water Soaps/Creams

Originally Posted by rolodave

First I heard of that.

The citric acid in lemon juice serves as a chelating agent to combine with the calcium and magnesium ions in the hard water. Although the ions are still present, they are less available to react with the fatty acids of the soap.
Some shaving soaps contain citric acid to help with hard water tolerance.

Citric acid is often used in powered form when canning fruits and some vegetables to act as a preservative. You can purchase it in the canning section of stores. However, in this instance, the citric acid is not obtain from natural sources such as lemons and lime, but it derived as a byproduct of black mold consuming sugar. If you see citric acid listed as an ingredient in products (including foods), it will have been derived in this manner.