Saturday, November 26, 2011

What Does Superfatting Soap Mean?

Soapmaking is a science. The "creation" of soap is a chemical reaction between oil and lye, known as saponification. Every oil (or butter) requires a specific amount of lye to "turn it into" soap. The soap term for this is saponification value. Soap calculators can be found on many soap making sites on the internet and will figure your lye amount for a specific recipe, at whatever superfat percentage you desire. Using the exact amount of lye you need to make the exact amount of soap with nothing left over (no extra oils) is called a 0% superfat or a 0% lye discount. Most soapmakers like to make soap that has "extra" oil or butter left over after the chemical process of soap making is completed because it makes the soap more moisturizing. This amount of "extra" oil is a purely personal choice. The average amount is about 5%. Superfatting too much can result in a softer bar of soap, less lather and a risk of premature rancidity.
If you want to make a few bars of soap that are exceptionally moisturizing for the Winter season, and plan to use them within a few months, it is perfectly acceptable to superfat as much as 15-20%. Keep in mind that you have to allow a cure time of 4-6 weeks after making the soap before you can use it, so, if you need extra moisturizing soap for Winter, get busy!!
Butters are commonly used as superfatting agents. I personally use Shea butter. I only superfat at 5% year round because I like tons of lather and a nice hard bar of soap. If extra moisturizing is more important to you and you can live with the decrease in lather and a softer bar of soap, superfatting is the way to go.
Happy soaping!!!!


  1. Thank you so much for sharing this information!!! I'm new to soap making and you explained superfatting so clearly that even I could understand it! Thanks again!

    1. Yes Agreed, super new haven't even started and still doing a lot of research!

  2. Thank you for the explanation, I too am new at soap making and am learning this as a college project. Some of the terminology is confusing and you explain it very well.

  3. great explanation, You have helped me a ton!!

  4. So question: If superfatting with shea and/or cocoa butter, would you add that BEFORE adding the lye or AFTER? I suppose I'd like an answer to that question regardless of ingredients. Do you superfat during the saponification or add it after? Some labels read "with added shea and cocoa butter", making me think these come in after the saponification. Thank you for the post. It does clearly explain what the term means.