How we make our soap
First we have to render the beef fat (the tallow). This is just melting and straining the fat several times until all the impurities have separated out from it and been removed. This is time consuming and messy, but it's not complicated.
Next, in one pot we melt the clean, rendered tallow. In another, we combine caustic soda and water. This forms a caustic liquid called lye, which at this stage of the process needs to be handled very cautiously.
We carefully combine the fat and the lye and blend with a hand-held stick blender until they emulsify, which means the are no longer separating from one another as oil and water usually do. Then we pour the soap batter into molds and leave it to set.
Finally, the soap needs to cure. A chemical reaction occurs during the curing time, in which the fat and lye become something else entirely – soap. The process is called saponification, and it’s what neutralizes the caustic properties and makes the soap safe and beneficial to use on our skin.
Once the soap is fully cured (which takes from 4 to 6 weeks), the original fat and caustic have been completely altered by the magic of chemistry and what’s left is just soap. They're now a different substance and there's no way to turn them back into fat and caustic.
How we make our soap extra skin-friendly
As well as the long cure time to allow the soap to fully saponify, there’s another strategy for making sure the finished soap is super-skin friendly.
If the raw ingredients at the beginning are in balance, the fully saponified soap will have no traces of any of them remaining at the end of curing. But if the ingredients are not balanced in relationship to one another, whichever was in excess at the beginning will also remain in the final soap.
So, we start with a little “too much” fat. It’s a soap making technique called “superfatting,” and it ensures that the final soap has traces of fat remaining in it. (In our case it’s around 6% extra fat.)
So we get certain insurance that there is no caustic left, as well as the moisturizing and nourishing benefits of tallow for our skin.