Only soap made in the traditional way, comprised of alkali salts of fatty acids (in more basic terms, oils that have been saponified with an alkali) is considered a “true” soap. True soap can be found today, made by large manufacturers to small artisan crafters alike.
True bar soaps contain surfactants that reduce surface tension between oil and water. Surfactants certainly do the best job of capturing dirt and washing it away.
It was previously thought that true soaps left the skin’s pH unbalanced since soap is slightly alkaline with an average pH of eight to nine. Human skin is naturally slightly acidic, with a pH of around four and a half to five and a half. Most research done today shows that, even after cleansing with soap, the skin reverts back to its normal pH very quickly. So having a pH balanced bar isn’t really as important as what was previously believed.
Although there are many true soaps that are all-natural, many soaps on the market today contain synthetic hardeners, fragrances, or colorants. This isn’t good or bad, just something of which to be aware. if you’re looking specifically for an all-natural bar, read the ingredients.