Every so often I get asked some variation of "the lye question" from customers or prospective customers: Do your soaps contain lye? (yes... and also no) Can you make me a soap without lye? (Nope) Is lye soap bad for your skin? (it depends...)
Do your soaps contain lye?
First lets talk about the several different ways that lye can appear on an ingredient label. I simply use the term "lye", since it is simple and clear and most folks understand what it is. Another name for lye is "sodium hydroxide" (chemical formula NaOH) which is probably a bit more precise since lye can also refer to the potassium hydroxide used to make liquid soaps. However, there are many who wouldn't recognize what that is (just look up all the jokes surrounding "dihydrogen monoxide" if you need a laugh) and would just lump it into the category of "chemicals to avoid" without giving it any more thought.
Probably my least favorite term is "wood ash extract" as this just seems like an attempt to skirt around people's discomfort with chemicals in general by giving it a greener more natural sounding name. Wood ash extract is, after all, just lye by a different name.
So all that is why yes, my soaps do contain lye but how can the answer also be no? That's when we get into chemistry. Like baking a cake, making soap involves chemical reactions. You can't "unmake" a bar of soap, anymore than you can "unbake" a cake. Once the chemical reactions have occurred, there's no going back to the original ingredients.
Here though, the analogy does fall apart a bit. If cake batter has eggs in it, the baked cake still contains eggs, just in different form. Soap batter, on the other hand, has lye in it but properly finished soap containsno lye.
How does that happen? Well, soap batter at it's most basic is a mix of sodium hydroxide (lye), fats and oils, and water. Once these ingredients are mixed together, they undergo chemical changes, that is the bonds between the molecules are broken and recombined. In a soap intended for use on skin, all of the sodium hydroxide molecules are broken up and reconnected to the fat molecules (with the help of the water). Another way to look at it is that sodium hydroxide, a base, is neutralized by the fatty acids in soap making oils.
Let's take my Simple Tallow Soap as an example. To make this soap, I combine just three ingredients: tallow, sodium hydroxide and water. Those ingredients undergo a chemical reaction when mixed together in the soap making pot, which results in a single compound: sodium tallowate, which a chemist would classify as a salt of a fatty acid.
None of the sodium hydroxide we started with remains, since it has all been broken up and combined with the tallow and water molecules to form something completely new! If you look at the ingredients on soap from large commercial operations, you will see ingredients like sodium palmate, sodium cocoate, sodium lardate, sodium tallowate, etc., this is simply what it looks like when you list what comes out of the process rather than what goes in.
So, do our soaps contain lye? No, the finished product does not contain any lye but lye is used in the soap making process.
Can you make soap without lye?
This answer is much simpler, no! You cannot make soap without lye, though there are products the are called "soap" but aren't, that don't use lye.
Lye (either sodium hydroxide or potassium hydroxide) is required to create soap. The method I use is called cold process (CP) and is a way to make soap from scratch. There is also something called "melt and pour soap" which uses a base that has already gone through the saponification process at the manufacturer (the lye and fats have already reacted) and has some added ingredients to allow it to melt smoothly.
Many liquid bath and body products (and most laundry "soaps") are actually detergents and have a completely different chemical process than soap. It does still get you clean but the ingredient list is a lot longer and the manufacturing process more complicated.
Is lye soap bad for your skin?
Almost all of my soaps are formulated for use on skin and thus are completely safe. The one exception is Household Tallow Soap. This soap is NOT formulated to get living things clean but rather, dishes, surfaces and laundry stains. This means that the soap recipe is calculated to leave no extra fat for moisturizing (all my other soaps have a certain percentage of extra fat to prevent drying out your skin). If you were to use this soap on your skin it would be very drying and potentially irritating, so it's not recommended.
If you've stuck with this to the end, thank you!I really enjoy the nitty-gritty science behind this essential item of everyday life and I'm happy to have the opportunity to try and share my understanding.
FAQs
What is sodium hydroxide? Sodium hydroxide is a chemical compound that holds or maintains the pH of skincare products, also known as lye. In soap, it's combined with animal fat or vegetable oil in a process called saponification. Essentially, soap is a mixture of base oils, a diluted lye solution, and herbal additives.
Is soap with lye bad for you? ›
Lye in Soap: All Real Soap Starts with Lye, and It's Perfectly Safe. With many consumers turning to organic and natural products because of health worries or concerns over environmental impact, it can be difficult to parse through the hype and understand what products are effective and safe.
What is the purpose of lye in soap? ›
Lye is the base medium that is required for the chemical reaction to convert fats in tallow, oil, or butter into soap. Without lye, the oils and fats will remain just oils and fats, which cannot lather or function like soaps.
Is soap without lye effective? ›
NO, chemically-speaking, soap itself cannot be made without lye. Soap is made by blending oils (like olive oil or coconut oil), a liquid (water, goat's milk, etc.), and an alkali (lye). Lye is needed to convert oils into soap.
Is soap made with lye anymore? ›
As negative as some perceptions of lye can be, all soap is made with lye – whether it's bar or liquid – and soap made well can be great for your skin.
Does Dawn soap have lye? ›
Is there lye in Dawn dish soap? Yes - it's listed on the packaging as 'Sodium Hydroxide' - otherwise known as lye. However, it isn't used for saponification. It is used as a pH adjuster.
Is Dove soap made with lye? ›
How It's Made: Sodium Palmitate is made my mixing Palmitic Acid with Lye (a solution containing water and an alkali). Summary: This Dove soap ingredient cleanses your skin, but may dry it out.
What is a substitute for lye? ›
In this method, you're replacing lye with baking soda, both of which are alkalies. However, lye is much stronger than baking soda. Heating up baking soda in the oven turns it from sodium bicarbonate into sodium carbonate, making it a slightly stronger alkali that'll better replace the lye.
What is Dove soap made of? ›
Dove is a “syndet” or synthetic detergent. Ingredients. Sodium Lauroyl Isethionate, Stearic Acid, Lauric Acid, Sodium Oleate, Water, Sodium Isethionate, Sodium Stearate, Cocamidopropyl Betaine, Fragrance, Sodium Laurate, Tetrasodium Etidronate, Tetrasodium EDTA, Sodium Chloride, Kaolin or Titanium Dioxide.
Does Ivory soap have lye in it? ›
Perfect example of this is good old Ivory Soap. Yep, they use lye and even tallow. They disguise the use of lye by listing the saponified ingredients ("out of the pot"). Once the oils and fats get saponified they no longer remain in their original form.
It is a vegetable soap (aka Castile soap) made from an oil and lye solution, specially formulated to be sudsy and gentle, while killing germs. The lather has the function of collecting excess dirt, puncturing germs and then removing them during the rinsing process.
Is all bar soap made with lye? ›
You cannot make soap without lye, though there are products the are called "soap" but aren't, that don't use lye. Lye (either sodium hydroxide or potassium hydroxide) is required to create soap. The method I use is called cold process (CP) and is a way to make soap from scratch.
Where does lye come from naturally? ›
A lye is an alkali metal hydroxide. Traditionally it was obtained by using rainwater to leach wood ashes, which are strongly alkaline and highly soluble in water, of their potassium hydroxide (KOH), producing lye water, a caustic basic solution.
What did they use for soap before lye? ›
Early Settlers
People in the 18th and 19th centuries made their own soap. They'd save tallow from butchering and grease from cooking for the fat. They'd reserve wood ashes to make potash, the alkali.
What is another name for lye soap? ›
Lye can go by two different names: sodium hydroxide (solid soap) or potassium hydroxide (liquid soap). Lye could also be hiding under a number of other names like sodium palmate (sodium hydroxide and palm oil), sodium cocoate (sodium hydroxide and coconut oil), and the list goes on for all different oils.
Is lye bad for your skin in soap? ›
Lye is a caustic substance that can certainly damage your skin if you're exposed to it. It can cause a number of problems, such as burns, blindness, and even death when consumed. But, and this is a big but, soap that is created with lye (which is all real soap) will do absolutely no harm to your skin.
Is lye toxic to skin? ›
Sodium hydroxide does not produce systemic toxicity, but is very CORROSIVE and can cause severe burns in all tissues that it comes in contact with. Sodium hydroxide poses a particular threat to the eyes, since it can hydrolyze protein, leading to severe eye damage.
Why did people use lye soap? ›
The main motivation for many people to choose lye soap is because of the natural ingredients, so they can avoid toxic chemicals that may be added to some modern beauty and body care products. Lye soap doesn't have any additives or dangerous ingredients.
Is Ivory soap made with lye? ›
Perfect example of this is good old Ivory Soap. Yep, they use lye and even tallow. They disguise the use of lye by listing the saponified ingredients ("out of the pot"). Once the oils and fats get saponified they no longer remain in their original form.
Why does lye soap have to cure? ›
Many consumers [and even some soap makers, especially newer] may not understand the importance of curing soaps. The curing process is what improves the quality and longevity of your soap so it doesn't turn to mush in the shower and lasts longer than a week.
