Do I need to add a preservative to my soap?

If you are making your soap properly (that is, without a ridiculously high superfat percentage, and ensuring you’re measuring & calculating correctly)—no.

Soap has a high pH because it is made from lye, which has a very high pH. This high pH wards off bacterial growth. The high pH of the soap will not wear off over time.

If you superfat your soap much about 7%, you may encounter rancidity (the excess oils in your soap will oxidize) or DOS (deadly orange spots). The best way to avoid this is by not superfatting your soap above 7%.

Something else that can interfere with the shelf life of your soap is adding acid to lower the pH (I’ve read about people doing this for shampoo). We’ve never tried it ourselves, but logically speaking, lowering the pH of the soap means its pH may no longer be high enough to ward off bacterial growth.

← Older Post Newer Post →


  • Ideally 5% super fat is perfect.this does not include the essential oils . Another thing to rember is to add EO after emulsification.
    Very high superfat is required in coconut oil Castile soap as coconut oil is dehydrating.

    Joya on

Leave a comment

FAQ - In addition to reading through these FAQs, you can also learn more about preservatives by reviewing the information on this page.