Some people hear that lye is used in handmade soap and are nervous about the safety of the product. Rest assured, there is no active lye in the end product. When a soaper creates a recipe, they calculate the amount of lye (sodium hydroxide) needed to complete the chemical reaction for the oils they use. The chemical process taking place during soap making is called sopanification. After sopanifying, the oils and the lye solution are no longer the same as they were before the process. The resulting salt is safe to the touch. That is why you will sometimes see ingredients on handmade soap listed as salts (sodium cocoate), the combination of sodium hydroxide and coconut oil.
Other ingredients may be listed as well. According to FDA guidelines, anything that is not a botanical must be listed in a very specific fashion. For example, one of the colorants I use has to be listed as this:
Aqua/Eau/Water, D&C Green No. 8 (CI 59040), FD&C Yellow No. 6 (CI 15985), Phenoxyethanol (and) Benzoic Acid (and) Dehydroacetic Acid
As a soaper that likes things to be as natural as possible, this makes me cringe. But, don't worry. Even the soaps that include synthetic fragrance oils and colorants are about 95% natural. These ingredients make up a very small percentage of the total.
Lastly, and in my opinion most importantly, is the presence of glycerin. During saponification, glycerin is produced. Glycerin is a humectant, which means it attracts moisture. It is was makes handmade soap so nice and skin softening. In commercially produced soap, the glycerin is extracted to be used for other profitable products such as lotions. The rest of the commercial cleansing products are detergents. They use chemicals to produce suds. These chemicals can cause drying and irritation of the skin.
To sum up, look at the ingredients list. You want to see botanical oils and lye (or sodium hydroxide). Be smart about looking at the chemical names. Some things that sound synthetic really are not. Remember, sodium cocoate is just saponified coconut oil. Also, colorants often have very technical sounding ingredient lists. Even though synthetic colorants or fragrances are sometimes used, it is such a small portion of the overall ingredients that it doesn't detract from the benefits of using real soap.