Thread: glycerin added to shaving lather

When a fatty acid is saponified using either either sodium or potassium hydroxide, the result is the salt of the fatty acid (soap) plus glycerol, also called glycerin or glycerine. For soaps produced in an industrial setting, the glycerol might be removed and sold as a separate product. In other instances the glycerol is left mixed with the soap.

Thus, for soaps produced in small batches from fats like tallow, palm oil, etc. and sodium and potassium hydroxide, , the glycerol (glycerin) is likely to be left in the soap. In such a case, it might not be necessary to add glycerin.

However, if you find that the shaving soap has been produced by combining cosmetic grade salts of fatty acid like sodium palmitate, potassium stearate, etc. it is possible that the glycerol has been removed. In that case you may find that the addition of glycerin will improve your lather. You might just be adding back the glycerol that was removed during the purification process.