If you’ve ever gone down the handmade soap rabbit hole, you may have come across the term “superfat.”
It sounds very scientific.
Thankfully, it’s actually pretty simple.
First, how does soap become soap?
Traditional soap starts with fats or oils and lye.
When they’re combined in the right amounts, they go through a chemical reaction called saponification. The fats or oils react with the lye to form soap and glycerin.
But a soapmaker doesn’t necessarily want to use enough lye to react with every last bit of oil in the recipe.
That’s where superfat comes in.
So, what is superfat?
Simply put, superfat is the amount of oil or fat left unsaponified in a finished bar of soap.
Soapmakers commonly create a superfat, also called a lye discount, by using a little less lye than would be required to completely saponify all of the oils in the recipe.
For example, a recipe formulated with a 5% superfat is designed so there is more oil available than the calculated amount of lye can fully saponify.
It’s intentional, and it’s one of the many decisions that goes into formulating a good bar of soap.
Why does it matter?
Because making soap is about balance.
The oils and fats, water, lye, and superfat all play a role in the finished bar.
But more superfat doesn’t automatically mean better soap. The right amount depends on what you want the soap to do.
Different soap. Different job.
This is why we don’t formulate every Del Toro Ranch soap exactly the same way.
A bar you use in the shower has a different job than a soap designed to tackle dirty hands, grease, and grime.
Our Shop Bar, for example, is intentionally made with a lower superfat than our everyday body bars because we want it to be a hardworking clean up bar.
Different purpose. Different formulation.
That’s one of the things we love about making soap from scratch. We can formulate each bar for what we actually want it to do.
The quick takeaway
Superfat is simply the portion of fats or oils intentionally left unsaponified in a bar of soap.
It’s one small part of the recipe, but it’s another example of why knowing a little about how something is made can help you better understand what you’re buying.
Go ahead. Read the label.
Sources & Further Reading
American Cleaning Institute
Glossary of Cleaning Product Terminology
Bramble Berry
Superfat (Lye Discount)
