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More than once, a person browsing my table at a market has said something to the effect of "handmade soaps are so neat, but they don't really lather that well, right?" Which has surprised me and also led me to believe that this might be a common misconception if more than one person believes it.
The thing is, no two soap recipes are identical and some ingredients suppress lather while other ingredients encourage it. So I wanted to share a little bit about soap ingredients, what they do and how it's possible to create a wonderful lather in a handmade soap.
Let's start with ingredients that help improve lather.
Oils and butters all add different properties to a bar of soap. Some of them have a higher cleansing value (meaning they can strip the skin), others have a higher skin conditioning value (meaning they add moisture to the skin). Some add to the hardness or softness of the bar, and others contribute to lather.
Using the right additives can significantly increase the lather of soap. Anything with a high sugar content will help with this. I've used all of the following to boost the lather in my soaps.
To learn more about soap additives and lather, there was a really great lather experiment hosted by Kenna of Modern Soapmaking.
If you have encountered a handmade soap with poor lather, there are a few things that can cause this.
Single Oil or Single Fat Soaps
Some people like to make castile soap, which is made with 100% olive oil. While it's very gentle on sensitive skin, it tends to be a slimy bar with very little lather. And it has to cure for a full year before using, so by this time many fragrances will have faded away.
100% lard soaps make a hard bar that is creamy and conditioning when used; but again, very little lather. Most other oils, fats and butters can't be used in this way. The final bar just comes out gross.
Superfat is a term used in soapmaking that means a lye deficit. You use less lye than is needed to fully saponify the oils (saponify means turn into soap). Soap makers pad their recipes with a minimum of 5% superfat to ensure they don't accidentally create a harsh bar. I use 6-7%, others use 8% or more. Using a superfat allows some of the oils to remain behind on the skin for moisture. But the higher the superfat, the lower the lather.
Too Much Butter
While shea, cocoa and other butters are amazing ingredients for the skin, these ingredients are also known to kill lather.
If there is a lot of magnesium, calcium and/or iron in your water, these metallic ions interact with the soap molecules and reduce lather. The only way to get around this is to either soften your water or use a product with a harsher synthetic surfactant instead (like body wash - ugh, plastic waste).
As you can see, there are a lot of variables that contribute to lather quality in soap. So if the only handmade soap you have ever used had poor lather, please consider trying one from a different maker!