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What is Lye Soap?

Is there lye in your soap?

This is a question I get asked a lot. The short answer is yes, but since it's never that simple, let's discuss the long answer.

What I'm going to tell you, if you don't know what lye soap is already, might shock you.

All soap is lye soap. Yes. All. If it's actually soap.

But what about the liquid body wash I use? Does that have lye in it? How would I find it in the ingredients list?

We tend to call anything that cleans soap, but that doesn't actually mean that it is soap. Confused yet. Well, let me try to clear it up.

Let's start with the actual definition of soap.

Soap: A substance used with water for washing and cleaning, made of a compound of natural oils or fats with sodium hydroxide or another strong alkali, and typically having perfume and coloring added.

The actual make up of soap is, in fact, a mixture of oils or fats and lye (aka sodium hydroxide or potassium hydroxide).

The process of mixing these ingredients (oils/fats and lye) is saponification.


You can not have soap with out this conversion happening. If this process has not happened, you have something else entirely.

Let me explain another way by showing you what is in the "soaps" we often find at our local stores.


We all know there are a TON of soap bars to choose from at the store. What is in them is a whole other post so I will try to keep that short, even though it's going to be very hard. :) Sodium hydroxide or potassium hydroxide (lye). This is what we are looking for.

I am also going to try not to give too many brand names because this is not about bashing or praising companies and what they do/put in their bars. This is simply to inform what soap really is or isn't.

This bar below is something that I had at home.

There are a lot of big words in here and honestly, I have no idea what all of them are.

One thing to keep in mind is that sometimes companies get around saying that there is lye in something by putting an oil and sodium hydroxide together and calling it by it's new chemical makeup.

Example: Sodium Tallowate (the first thing listed) is actually lye and animal fat. You can google it. It's true. Why do they do this? My theory: people are scared of lye. This is often why people ask me if there is lye in my soaps. Why are people scared of it? I will explain that later.

So yes. This bar is soap. Lye and oils were mixed together for this bar.

Liquid Body Wash

Before we go too deep into liquid body wash, I have to point out that potassium hydroxide is often used to make liquid soaps and sodium hydroxide is usually for hard bar soap. So what we are looking for in these liquid washes is potassium hydroxide.

So is body wash soap? The answer is some are and some are not.

Let's look at the picture, below, on the left first. There's a lot of sodium-something on this label. If you remember sodium tallowate was, in fact, lye and animal fat. So does that mean that sodium lauryl sulfate is also lye and something else? The answer is no.

To save some confusion we will concentrate on the word sulfate.

Sulfate : Sulfates act as surfactants or agents that reduce the surface tension of liquids such as oil and water, allowing them to spread more easily.

Sulfates are a much debated topic. Some say they are dangerous, some say they are natural. I honestly have no idea what I think about them, but I know one thing, they are not lye. And that is where I will end that discussion for now. You know, to stay on topic.

So no the left picture is not soap. It is made up of a lot of different things, but lye and oils were not mixed to make soap in this case, so it is not the true definition of soap.

The picture on the right is a liquid wash that is usually well known with people that shop for the most natural and transparent label ingredients. As you can see they use ingredients that I can pronounce. :) And as you will also see there is potassium hydroxide. Clearly this is considered soap. It is made in a different way from a soap bar, but it is still lye and oils coming together to form soap.

Liquid Hand Wash

Keeping in mind that potassium hydroxide is what is often used in liquid soap, that too will apply for hand wash. Here is a picture of a hand wash ingredient label.

So again, we have a sulfate as one of the first ingredients and no signs of potassium hydroxide to mix with an oil or fat. This is not soap. Yes it says hand SOAP, but it does not fit the definition of saponification.

So this is what soap is and is not. It gets confusing when something that is made mostly of detergents (ie: sulfates) is called soap.

So yes the old lye soap that so many grandma's made "back in the day" is the true soap. Lye Soap

Fear Of Lye Soap?

When someone asks me if my soap is lye soap, it tends to be asked with a bit of fear. It seems, the assumption is that all lye soap is harsh!

This is absolutely NOT true!

I think somewhere, along the way, in the marketing of these new found ways of making new, better, and even cheaper body washes (I'm talking about the detergents here) the people trying to sell these *ahem detergents, may have misled a few people that lye soap is bad.

I hold no grudges. It's all about selling a product. I get that. However, I would love to erase the stigma behind lye.

First of all, and I hope we have established this if you made it this far, lye soap is actually soap. :)

Second, if made correctly, a bar of lye soap can be the most gentle soap you can find. Don't get me wrong, soap can also be made in a way that is very harsh on the skin. Some people like their soap to be lye heavy, meaning the recipe is made to have things a bit off balance so the lye comes through, but this is not how I make my soap.

If you go back to the liquid body wash picture on the right you will see it says "none remains after saponifying oils into soap and glycerin". They are talking about the lye. This confirms my theory that people are scared of lye. And yes, if the recipe is done right, there is not lye present any longer because its mixed and becomes something else. Sort of like making a cake. Once you mix the eggs and flour (and all the other ingredients) you don't serve people eggs and flour anymore, you serve them a cake.

A nice creamy bar of soap, made from lye, from a well formulated recipe is not a scary, or harsh thing. It's all in the balance and is actually quite the opposite of harsh.

If you are interested in learning more about the process of soap and what it is, and how it's made, I do give classes. I schedule 2 a month for anyone who wants to sign up. You can find the next scheduled class on the events page.

Thanks so much to my customers, that keep me going, with this soap adventure. You are greatly appreciated!


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