This page will show you how to make lye soap in an iron pot over an open fire. It has a lot of pictures to help you get the picture of the process. If you do a search on the internet of soap making, you’ll see references to laboratory scales, exact temperatures and other discouraging terms. Let me begin by saying that your grandmother probably made soap just fine without these and you can, too!
There is a legend that soap was discovered by the Romans on Mount Sapo. The legend goes that on the top of the mountain was an altar where animal sacrifices were taking place. Below was a stream where the Roman women did their laundry. They noticed some white flakes in the stream and found that the laundry got cleaner when the flakes were rubbed in.
Someone soon discovered that the rainwater came down and mixed with the ashes which produce lye. The lye broke down the animal fat and soap was being made. I don’t know if it’s true, but you’ll find references to soap in the Bible and note that the Lord uses ashes in Old Testament sacrifices for cleansing. (Numbers 19:9)
The ingredients in this recipe are:
- 2 gallons of non-tap water
- 10 ounces of lye by volume and
- 5 lbs of tallow (fat from beef)
If you use any other kind of fat except lard, you’ll have to change the amount of lye and vary the temperature. (see my notes regarding lard at the bottom of this page).
All soap is made with these 3 ingredients, even commercial soap. It is the basis of all soap. Some people see us at shows and say, “I’d never use that lye soap!”. They don’t realize that all soap is lye soap!
Below is a step by step diagram of how to make it.
First, render the fat out by cutting it into cubes about 1″ square. Trim off any part that looks like meat or isn’t white.
Cutting the Fat into cubes
It looks like potatoes cooking
When the fat is cooked down and you’ve gotten all the grease out of it, it’s time to strain out the solids. Make sure that you don’t burn the fat as the soap will not be as good. I use cheese cloth in a funnel shaped strainer. The picture shows it coming out as a beautiful amber color.
If you are beginning your batch with lard or tallow that is already rendered (i.e. you bought lard at the store in a tub) begin your soap at this stage.
Now, measure out 5 lbs of the liquid fat I have a stainless pitcher that just happened to hold half that amount so I just use 2 of them. Bathroom scales are sufficient for your measurement. Put the fat in the iron pot and make sure that you have pure, clean liquid.
Next, add the water slowly into the fat. By adding it, you’ll cool it down and it will start to solidify. You always hear that oil and water don’t mix, but you’re about to make it happen!
The mix will start to turn into a greasy cream. Start your fire under the pot. I use small splits of pine. With these you can bring the heat up quickly if you want to and also you can control the heat better.
You’ll want to make sure that the mix looks blended. You don’t want to add the lye into it until it is. Let me stop and say that during this step, you’ll want to use some caution. First of all, Lye is an alkali and will burn your skin or eyes severely. Secondly, from this stage on, do not use any utensils that are aluminum as the lye will act like an acid to it. The below picture is what you’re looking for. It will look consistent and not show any separation of the oil.
Now measure out 10 ounces of lye. This is Red Devil Lye that is found in the grocery store along with drain openers. Yes, that’s what your Granny used, too! She may have used lye made from the ashes of hardwood fire, but it’s the same chemical. Powdered lye has been around since the 1700’s and is easier to get consistent soap from. You may have heard folks talk about lye soap that burns the skin, but if you accurately measure the same amount, you’ll get the same soap. Here, I use a glass jar that has the ounces labeled on it. Fill it to the 10 ounce mark and Sprinkle slowly and stir so that it all dissolves. I use a wooden paddle to mix.
You’ll notice that the saponification is already taking place! Look closely and note that soap bubbles are forming on the top of your liquid.
Now bring the fire up under the pot. You’ll want to cook the soap mixture from 30 minutes to an hour. Stir occasionally and keep it from boiling over. A slow boil is perfect.
Now, in the final stages it’s all a matter of sight. When you’ve cooked it a while it will look like very thick, creamy chicken soup. You will want to have your molds ready as the mix has to be poured up as soon as it comes together. We use old baking pans with Saran wrap in them to prevent sticking.
Note that soap is already forming on the edge!
Ok, here is the most important picture on the page! Notice that I’ve dipped my wooden paddle into the mix and it sheets off of it. You can click on the picture to enlarge. But don’t be fooled! Before it gets to this stage, it will look like it’s going to sheet but will still have a little clear drop if you wait a minute. Don’t pour if you see any clear liquid hanging with your icicles! It should look like hot wax that’s hardening off of the paddle. When you have sheeting like this, pull the fire away with a shovel and pour it up!
A soapmaker’s happiest moment!
Now you can pour it into molds. Once again, make sure that you don’t use aluminum. The soap will take at least a couple of days to harden enough to cut into bars. Even then it will be softer than the final product. It is usable as soon as it’s hard enough. It will probably take a week or so to really get hard.
See my P.S. at the bottom regarding cure time.
A lot of people ask me what the cure time is on my soap. This soap has no real cure time. What they are referring to is when the lye content or Ph is down low enough to handle with your bare hands. Cold processed soap (soap done without a fire) has to be set up for several weeks before the lye is at a reasonable amount and it won’t burn your skin. This recipe allows the lye to break down and dissolve during the cooking. In fact, when I demonstrate this at shows, I clean my pot out bare handed as soon as the temperature is cool enough on the pot. It is an extremely mild soap and has never burned me chemically.
If you mix a base (Lye) and an acid together you get a neutral. Chemically, soap is a neutral and 7 would be perfect. But don’t worry if it’s not a 7. Just look at these!
- Camay 9.5
- Dial 9.5
- Dove 7.0
- Irish Spring 9.5
- Ivory 9.5
- Lever 2000 9.0
- Palmolive 10.0
- Zest 10.0
If you are using a cast iron pot as I do, make sure that you don’t put cold water in a hot pot. Wait to clean up until it’s cooled down. Cold water will crack the cast iron and ruin the pot. But once it’s cool, put water in it and simply wash it out. There will only be soap in it so it comes very clean! Don’t forget to wipe it dry and grease it down to prevent rusting.
This soap does not make a lot of suds as other soaps do. If you want suds, you can experiment with coconut oils. Also, a lot of folks have asked about adding herbs and things. If you want to put these in, add them in after the mix sheets and you’re about to pour. I leave my soap as basic and simple as possible. I get a lot of requests from deer hunters and people with allergies. The hunters like it because it doesn’t leave a smell on you and a lot of people have told me that their skin cleared up after using it. One final word-this recipe will also work using lard instead of tallow. It does take longer to cook, though. Normally, with lard you will have to cook it 3-5 hours. When it’s ready it looks more like clear hot-glue. Just look for the consistency to be the same (no separation).The soap is whiter and softer than the tallow soap but it does make more suds. Have fun making your soap! Don’t forget….
Granny did it, so can you!
P.S. (Paul says) there is NO CURE time on this soap as far as being safe to use. It does take a couple of days to harden enough to use and will continue hardening for a few weeks after that. This soap is safe to use right out of the pot. Cold processed soap (made without cooking) takes several weeks before it’s safe to handle.