How to Make Lye from Ashes

Last year I had the opportunity to visit Cove Fort, a historical site in Utah, where there was a big pioneer event going on. Among the many fun things I was excited to see was this ash hopper, a tool that was used in pioneer times and back through history to make the lye needed for soap. Considering my profession, you may understand why I was drawn to this particular piece of history.

What is lye?

It is a strong alkali also known as sodium hydroxide. This is the chemical that is mixed with oils and water to create soap. We need both lye and oil or else soap just wouldn’t happen. These days we have a synthetic version of lye that’s easy to use accurately to create beautiful bars of soap. This is thanks to Nicolas Leblanc, a French man who created a method back in 1789 for making this synthetic lye. 

Before this creation, the standard was to make your own lye by gathering ashes from the fireplace. Since they used fires to cook their food and to stay warm there were plenty of ashes ready to be used without cost.

Once these ashes were gathered up they were poured into a wooden ash hopper like the one in the picture. They would then pour water over the ashes and let it sit. This process allows the water to soak up the alkali properties of the ashes.

At some point when they thought the water and ashes had soaked long enough they would take out the stopper located at the bottom of the hopper and let the water, which now contained lye, drain out into a bucket.

Here’s the thing. When I make soap I carefully weigh out all the ingredients, including the lye. The problem with the lye made in an ash hopper is that you aren’t sure of the strength of the lye. This meant that it was harder to make soap with consistent results.

But there were tricks to help.

If you put an egg in your lye water and it floats you know your lye water is strong enough and ready to make soap. If the egg sinks, then you better add more ashes to the hopper and go another round with the soaking process. Each time the ashes are soaked in the water the solution gets stronger. 

When the solution is ready it is combined with oil to make soap. Often these oils were fats from whatever animals they had slaughtered to be used for food. They would gather up the fat and render it, which means to cook it until the fats separate into layers. The impurities rise to the top and are removed.The fat that remains can be used in soapmaking.  Rendered fat from beef is called tallow and from sheep is called lard. 

It’s quite a process they went through to make soap as they then cooked and stirred their soap over a fire to create a product that helped them keep clean. 

Of course, these days I am grateful we don’t have to go to all that trouble. Aren’t you glad?