Period Hot Process Soapmaking

An overview of the process used in the middle ages to make soap, and how you can recreate it today.

Ah, soapmaking... a tradition passed down and refined throughout the generations, until you can now go to the store and buy soap in a thousand shapes, sizes, colors, and scents. But have you ever wondered how it all began, and how the whole thing works? Soap making dates back thousands of years, to the days when it was discovered that animal fat and ashes could produce a substance useful for removing dirt and oil. Over the centuries, the process of making soap was refined to the point of hot process soap making, which is what will be discussed here.

This is called "hot process" soap making because heat is added to the mixture to speed up the process of saponification, or the process by which soap is made on a chemical level. Heat is produced by any form of soap making; this way, by adding heat to the mixture, the process is faster and much more under your control.

To make soap in the "period" way, or the way that it was made in the middle ages, you'll need a few items. First of all, you're going to need a large kettle or cauldron. It should be filled with animal fat and cooking of some sort, as the fat and grease supply you with the oil needed for saponification. In period times, this fat would be supplied by the animals that were hunted or slaughtered; if you hunt, you can get the fat that way, or you can inquire with a butcher or meat market to find out what they do with the fat that is removed from their meat.

Once you've got the animal fat in the kettle, you'll need to add and equal amount of water as well as get a fire going underneath it. The fat will begin to melt slightly, and will eventually start to boil. Once boiling, let the fat continue to cook down, or render, for several hours; the rendering process removes impurities from the fat and separates the solids from the liquid oil.

While the fat is rendering, it's time for you to get the potash (aka lye) you need to make soap. Unlike today, when you can buy lye at most department stores, people in the middle ages had to extract their own from wood ashes. To do this, they would have a barrel cut down and placed into a groove that they had cut into a large stone slab. The slab would have a small lip carved into it so as to allow liquid lye to pour off as a finished product. (You can cheat a little bit on this one, and make a concrete cast in the shape that you need. I won't tell.)

Fill the bottom of the barrel with straw and small sticks, and the rest with wood ash (which will be readily available after each soapmaking project, as you're keeping a fire going pretty much the entire time.) Place a clay jar or other vessel under the lip on the stone, and slowly begin to carefully pour water over the ashes. A brown liquid will eventually begin to come out of the bottom of the barrel and pour into your vessel... this is your lye. Going back to your fat mixture, make sure that it is still boiling well (it should have been boiling for a little while by now.) Put out the fire and add a portion of water to the kettle that is equal to the first. Let the mixture settle and cool overnight; the sweet, rendered fat will float and harden on top, and the impurities will sink to the bottom.

Once the fat has hardened and cooled, remove it from the first kettle and place it in a second one. Add lye at a ratio of around 2 1/4 oz. of lye per pound of fat. Place the kettle over a fire and let it melt and boil; soap has formed when the mixture becomes frothy. (Please note that this may take as long as 7 or 8 hours, depending upon the amount being made and the strength of the lye.) Now all that's left for you to do is remove the soap from heat and pour it into wooden molds. Allow it to solidify, and remove the molds; cut into bars.

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