What is Lye?
Lye, or sodium hydroxide, is a very caustic chemical capable of causing serious damage. It can burn skin, cause blindness, and even cause death if ingested.
And yet, this dangerous chemical is one of the main components of all soaps, both homemade and store bought. Old timers will tell stories of how harsh lye soap is on the skin, but how well it cleans clothes.
Is Lye Dangerous?
It is true that extreme caution must be taken when using lye in soap making. Protective glasses should be worn, arms and legs should be kept covered, and gloves should be worn.
Most older soap making books and soap makers have recommended keeping vinegar on hand to neutralize any lye that may come in contact with your skin. This is no longer advisable. The vinegar will create more heat when it comes in contact with the lye. Instead, it is best to run the exposed area until cold water for 15 minutes.
Good ventilation is another consideration when working with lye.
So, why would a soap maker continue to use such a harsh product?
What is lye used for in soap?
Lye, when combined with fat, is used to create a chemical reaction called saponification. The end result is soap plus glycerin.
What is Lye Soap?
The other main ingredient of soap is fat – tallow, olive oil, or coconut oil, for example. When fat and lye are combined in proper proportions, a chemical reaction called saponification occurs. The end result is soap plus glycerin.
Glycerin is often removed from factory produced soaps which is why soap is often drying to the skin. When properly prepared and cured for several weeks, no lye remains in the final product.
So, yes, lye is a dangerous chemical, but soap make with lye is perfectly safe to use.
Is Lye Soap Harsh?
So why does “lye soap” have a reputation of being harsh? In days past, homemakers made soap using lye made from wood ash. Sophisticated scales for measuring were not available, and often too much lye was used.
When saponification occurred, some lye was left in the soap, making it harsh on the skin. It is vitally important to measure carefully so that the correct amount of lye is used.
To answer the question, yes, soap made with lye is completely safe and is not harsh when made properly, using every precaution.
Have you avoided “lye soap”, thinking that it was harsh or unsafe?
Where to buy lye for soap making. (Purchasing through this affiliate link helps to pay my blogging expenses, and doesn’t cost you a penny more.)
Recommended Reading:
Simple Natural Soapmaking by Jan Berry
Thank you for visiting Learning And Yearning. May "the LORD bless you and keep you; the LORD make his face shine upon you and be gracious to you; the LORD turn his face toward you and give you peace." Num 6:24-26
Kara Yeckley says
Yes, until you set me straight 🙂
Susan says
🙂
Sonya says
I just made coconut soap for the first time and I am a little anxious about using it! I have very sensitive skin
Dianne Fincham says
If you use 100% coconut oil you need to do a higher superfat, 25% – 30% or the soap will be very drying, and harsh on your skin.
Joseph says
What are higher superfats? I really did not understand this. Do you have a formula?
Estee Bowman says
When you make soap and you use a superfat of zero percent — that means all the oil is used up by the lye during saponification. If you soap at 5% superfat it means that 95% of the oil is used up by the lye in the saponification process and 5% of the oil is left floating around in the bar. If you soap at 90% – then 90% of the oil is used up during saponification and 10% of the oil is left floating around in the bar. So superfat is really the amount of oil that was not used up by the lye in the saponification process and is left floating around in the bar of soap you made. That is why some soap recipes have you add the “good oil” or bonus oil after you reach trace. For example you might use 95grams of Sunflower oil and 5 grams of castor oil (bonus oil) if you soap at 95% — what you do in this case is ===> soap with the Sunflower oil (95 grams) with enough lye to use up all the sunflower (0% superfat)– after it has reacted (saponification – light trace) add the castor (bonus) oil.(meaning all 5% of the oil floating around in your bar will be castor). However, I have found that adding oils as bonus oils may be misleading because it seems to me that the lye can “disassociate” with the sunflower and scoop up the castor — at least I noticed this when I added vinegar late in the process once, and it seemed the process reversed itself and then went forward again. I personally am not a big fan of bonus oils or high levels of superfat — I like my soap to clean me and not leave oil on me — if I want some oil I can apply it after my bath. One note, and today I made this mistake, I lathered my face with my homemade soap (that I use regularly) and left it on (did not rinse it immediately) while I addressed something else (knocked over stuff) … so I rinsed after a few minutes — and my face has a yellow cast (light burn – or reaction to the soap). That is to say, if you are worried about a soap being too strong, dilute it (lather in you hands with water) and rinse quickly — full concentration and leaving it on a long time will increase the probability that you will react to your soap — for me this is a better approach then relying on superfat to make the soap milder. Additionally, some oils do make milder soaps — 100% sunflower oil soap is MUCH MUCH milder than 100% coconut oil soap (which would probably be good only for laundry after flaking and dissolving then adding to the wash — because 100% coconut, especially fractionated coconut oil is SUPER SUPER strong). My experience is : coconut oil (regular or fractionated), aloe and babassu are super strong and should never be used at more than 15% of the oil by weight — unless you are making detergent (which will be flaked and used dissolved/diluted).
Susan Vinskofski says
Thank you for sharing your expertise!
carrie says
Thanks!! I have been avoiding making my own soap for this very reason. I am so grateful you shared your knowledge!
Susan says
Let me know how it works out for you, if you do decide to go ahead and make your own soap, Carrie.
Krista says
So is this why no pretzels list it as an ingredient and that’s illegal if I’m not mistaken? I accidentally typed uklegal lol.
But pretzels(crunchy and soft) all have a distinct taste to them. Is it malt that I’m tasting? I was thinking it was lye this whole time and then read about how harmful it is.
Lori Davis says
I have made my own soap. I was nervous the first time, but now that I have learned to make it properly, I love making soap!
Susan says
It’s a good feeling, isn’t it?
Sue says
If I wanted to have a very basic soap ingredient sent to Kenya Africa what could I do that is very simple. Idk what can be bought there but my friend says soap there may cause cancer so they are discouraged from using it in the private areas much. I would love for her to make simple and maybe sell a few or share them. I just want to help them. Ty
Susan Vinskofski says
Hi Sue, There are soaps made with just lye and olive oil, or you might consider sending a melt and pore soap base. I’m curious now about the soap they have to use and what is in it.
Kresha @ Nourishing Joy says
I’ve been making soap for years but never thought someone would think it’s dangerous. What a great post! It’s always good to see the other side of the coin. 🙂
Thanks so much for sharing this in this week’s Thank Goodness It’s Monday carnival. I’ve pinned it on our “Thank Goodness It’s Monday” Pinterest page, too. 🙂
Blessings!
Kresha from NourishingJoy.com
Susan says
Thanks for hosting the carnival, Kreesha!!
Anissa says
I still really want to learn how to do it from scratch! If I need to buy the lye, I might as well buy the soap and save myself the hassle. I will continue looking, as I believe this is a good skill to have tucked away ‘just in case’.
Susan says
You’ll have to let me know what you come up with. I think being exact with measurements will be the biggest challenge.
Caelee says
For a short while I had my own soap making business, it was a small business and I stopped because I got caught up in my studies and I didn’t make it a priority. Now I won’t use store bought soap, I still have leftover stock that I use today (3yrs later). When you read the labels of store bought soap and see the chemicals that go into it, you may also change your mind about the cost and time that goes into it. One of the great things about it was that I always had soap on hand that I could use for gifts for birthdays and christmas. Handmade gifts are great to receive!
April says
I make my own cold process soap with lye and this is such a misconception among the public. What makes it worse is some homemade soapmakers add lye as an ingredient in their soap. Like you say in your article there should be no lye left in your finished soap product. What you have are saponified oils and lye doesn’t remain any longer. Great article!
Susan says
Thanks, April!! All soap is made with lye, of course. The other bars on the market are detergents, as far as I know.
Heather@Mommypotamus says
Great post! I often get asked if it’s possible to skip the lye when making soap because of the perceived harshness of the end result. Love this historical look at how it got that reputation!
Susan says
There is no such thing as soap without lye, as you know, of course!! Thanks for visiting, Heather. I appreciate you and your blog!
Katie says
I’ve made soap many many times and never used any lye and all the soap came out great. Many natural soap companies don’t use lye. You don’t have to have it to make good soap.
Susan Vinskofski says
Could you explain how that’s made, Katie?
Meriem says
Hi
So what do you use instead? Thank you
Susan Vinskofski says
Soap isn’t soap, by definition, without lye. And as my article explains, it needs to be used with caution, but is perfectly safe in the bar of cured soap.
Esther says
Hi.what do you use instead of lye?is it a bar soap?
Heather Brumbaugh says
Glysirin
Deana Jones says
Know how you get glycerin? With lye. There is no such thing as lye free soap. Period.
Deb says
Learned about soapmkaing from the time I was a toddler. We butchered at my grandparents’ and made luye and tallow over a fire in a HUGE cast pot. we ate the lard and used tallow for soapmking. We did use Red Devil lye from the store and just tallow. Made for great soap for wringer washers. We all had them then. Used store bought for our bodies, I’m 51, but did clean grease from clothes well. We quit that when I was 10 or so. For the past 14 years I have been making my own body soaps and shampoo bars with olive oil and other oils. No access to the fat like when we butchered. I now make it using my stand mixer with a crdboard piece over the top around the mixers as my hand won’t stir that long. Works great and I know all the ingredients, and how to pronounce them. LOL Never use gloves or safety glasses. I agree the old fashioned way of making wood ashes makes lye very harsh or we have no way to measure it for strength. Wouldn’t have it any other way making lye soap myself from commercial lye. I add herbs and EO to most of them also. Love the smell of cinnamon soap.
Susan says
Although I didn’t grow up with all of this, I did wash clothes in a wringer washer for many years in my early marriage – including cloth diapers. We bought a house from a woman who made soap and there were boxes of it left in the house. I used that soap to wash clothes for years. Your soap making experience certainly exceeds mine; I just make plain soap!
Kathy @ Mind Body and Sole says
I’ve been making my own soap for the past year or so and LOVE it! I share the recipes on my site, here: http://mindbodyandsoleonline.com/links/making-cold-process-soap/ and here: http://mindbodyandsoleonline.com/links/soap-lotion-recipes/. Now that I know how easy it is and how much better than the store-bought stuff, I wouldn’t have it any other way. 🙂
Thanks for sharing on Wildcrafting Wednesday! 🙂
Susan says
Thanks for hosting, Kathy.
Jenn says
Hi Kathy, ??????? Thanks for sharing your website’s. ? I’m about to go check them out, because I would like to start making my own soap ?. I have a couple questions. You might even have the answers on your sites, but since I haven’t been on them yet, I’d figure I’d ask here, and maybe get even more suggestions and tips from people on here? ?
1st question: Do you make different scent soaps??? If so, what do you use for the scents?
2: Does yours and/or your family’s skin dry out often? My skin seems to dry out with a lot of ?bar soaps, but not the body wash. The only bar soaps that don’t dry my skin out so far is, Dove & Irish spring & Coast…I don’t like changing up the brands of soap I use, because just that alone can dry out your skin, just like changing up on your laundry soap ??, fabric softeners, etc.. As of last couple years, I’ll only use Dove body wash ?LOVE,?LOVE the foam, it’s a MUST TRY??
3: Do you make your own lotion?, laundry?? bar, etc..? Thanks?
Oh, If anyone that read this, if you have any suggestions ?(<~~suggestion box ?)or tips for me to make my own soaps?, shampoo, conditioner, laundry soaps?, lotion, etc.. please, ?? I would love to hear? them? ?
Thanks again
Jenn says
Awww, Don’t mind all the ???? Marks they put in on my comment. :'( They were all different emojis… Didn’t know I couldn’t add them, which is dumb, because we all know emojis are cool and funny and could make someone’s day. 😉
Elise says
I have, unfortunately, made some rather harsh soap myself until I learned to measure the lye very, very carefully. These days, I also always superfat my soap. Couldn’t ask for a better bar!
Susan says
So, is that adding extra fat to the recipe?
Claire says
What about lye used to cook pretzels? Is that unsafe, because it makes them taste really good, and I’d be sad if it did.
Susan says
Well, you’ve definitely stumped me on this one!
BethADen says
It is safe for eating the finished product but still very dangerous to work with. My daughter worked for a soft pretzel company for a few years and has many burns from the lye.
Kimi W says
Re: the pretzel question.
The lye is only used as a bath in which to dip the finished pretzel (or bagel), before salting the tops and baking.
It is the lye bath that makes the brown crust with just the right amt of crunch.
For those who choose to avoid it, you can search how to bake the baking soda and use that instead. It will replicate this action, and is a good substitute but the best crust really does come from the caustic lye dip.
Susan Vinskofski says
Thanks for the helpful info, Kimi!
Melanie says
Lye is sodium hydroxide. It is a very concentrated salt that is caustic only because of the extreme concentration. It is safe for pretzel making. It is probably very hot though. Aren’t bagels made the same way? I would think it’s safe to consume the final product but the process is probably dangerous and can burn the skin. Anything that has a high or low pH is bad for the skin. Hot liquids too. Boiling water, which has a very safe neutral pH level will burn the skin if spilled on it. The amount of lye left on a pretzel is probably similar in content to a bath in salt water. Hope that makes sense. It’s basic chemistry at work.
annlaura says
Nice post! My family has been making lye soap since I was almost 2yo. It’s very gentle when made with the right ratios. I use it as my face soap, and used it on my babies. A tip that is probably common – lye is a strong base, so keep apple cider vinegar out to counteract the lye if it comes in contact with your skin. Also, regarding the pretzels, there is food grade lye which is commonly used in baking as well as other food preparation.
Susan says
Yes, I always keep vinegar on hand as well. Thanks for letting us know about food grade lye!
Janet Westrup says
My grandmother used to make soap and cure olives with lye. If proper care is taken while making both there is no problem. Its important to keep children and pets away from soapmaking area also.
Since there is a slight bacon scent to the soap when using lard my dog decided to take a bite. From that time on I decided not to use tallow or lard for soap making. I purchased palm, olive and coconut oils which actually made a nicer soap. I added essential oils for the scent. The soap lasts a longtime and lathers even in ocean water. Great for camping.
Strong lye soap like the pioneers made is great to do laundry with. It will bleach the stains out of anything.
Mrs. J.
Susan says
Oh, that’s interesting that your dog was attracted to the smell! So, I guess that soap with extra lye does have its purpose.
Melanie says
If lard is properly rendered it should have no odor. At least, according to what I have read. I just made my first batch of soap using a variety of oils and store-bought lard. The lard had absolutely no odor.
Ruth says
My dad won’t use my soap because he’s worried about the lye – he actually told me not to let the kids use it because it would burn them! Meanwhile, we’ve been using it exclusively for months, with no side effects (except softer hands and shinier hair!)
Susan says
Oh, my, that’s a shame. But I’m glad you are getting great results!
Lori @ Our Heritage of Health says
Great explanation of the saponification process! Even though making soap with lye requires some precautions, I’d much rather use old-fashioned lye soap than modern soap that’s full of synthetic fragrances, dyes, etc.
Thanks for linking up to Old-Fashioned Friday!
Cindee says
Great post ! A nice lady approached me st a craft store looking at stuff in soap section. We chatted about Lye, I am a soap maker and she had a hard time understanding that you have to use Lye to make soap. By the end of conversation she got it. Thanks for post
Danielle @ Analytical Mom says
It does have a reputation of being extra harsh! Thanks for setting the record straight. 🙂
Christi says
Dumb question, but where do you get lye?
Susan says
Not a dumb question at all. I generally get mine here: http://amzn.to/12POCGP
fitness tracker says
I got what you mean, many thanks for posting. Woh I’m glad to find this website.
Here is my weblog – fitness tracker
oldschoolyoungster says
My mother makes lye soap at a historical state park using a recipe that’s over 200 years old. Its a pioneer settlement and the recipe dates back to even then (1770s) She lets it mellow for a week or two after its hardened and cut into bars. Its great for laundry, lice, fleas, eczema, psoriasis, acne, dandruff, poison ivy and family, its hypoallergenic and safe for dogs, cats, puppies, kittens, farm animals and even babies. We live on it, its a life saver!
Thanks for posting this article, too many people have misconceptions about this wonder soap!!!
Gina Marie says
Would love to know her recipe!
cassie says
Can we get contact info or a website to buy her soap?..
Lidia says
This is an extraordinary site. Am so glad I found it. I just recently bought this soap at Aco, yes, Aco hardware store. I have noticed my skin been soft, not dry at all. Told my husband about it. My grandson is 7 months old and suffers from eczema, and it is really bad, can my daughter use the lye soap on his body? I love the idea that there are no chemicals in the soap. I grew up in another country and soap made with lard was used, my hair and skin were always better
Susan says
Hi Lidia, I’m glad you found us, too. I’m not sure what soap you found at the hardware store. If it just says “lye soap” I would be afraid that it would be a bit harsh, although you haven’t found that to be true on your own skin. It’s just that I would think that a hardware store would carry soap used for cutting mechanic’s grease, etc. Homemade soap with lye in it would be fine for the baby as long as the soap is superfatted. That means using a recipe that doesn’t have quite enough lye for all of the fat in the recipe. A recipe with lard or tallow would be absolutely wonderful for him. I’m not a nutritionist, but it’s my understanding that eczema can be diet related, although chemicals and perfumes in things like laundry detergent could factor in as well.
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Ruthie Bay says
I found yr site on lye soap when I was wondering how much lye soap was worth. I have a lye soap dad told me , was home made by our great , great grandmother, and you was right, dad told me they would make it using ashes as one of the ingrdients. this soap has a date on it, 1873. my thought is ,if she home made it why would it have a date on it, unless they bought it back then and kept it down threw thefamily
Susan Vinskofski says
Sounds like you have a little sentimental treasure on your hands, Ruthie.
Brittany H says
As a soapmaker, I can tell you first hand that respect for the lye is the number one priority while soap making. Even seasoned veterans need to be cautious while making soap and never forget the dangers of it. While making test batches for new products, it is easy to disregard or minimize just a few ounces of lye water thinking such a small amount can’t do damage compared to the large 50 ounce lye water batches I normally do. Not!
I worked without goggles on one time recently. In all my years, I never had the liquid from a batch splash as I always keep the stick blender submerged. Well, I got lazy, didn’t put on my goggles and the batch splashed me just millimeters away from my eye ball on the delicate tissue below my eye. I rinsed it quickly with water, but even one drop, even for one second left a burn under my eyes for days.
Be careful soapers, but don’t be too afraid that you never try it. It can be most amazing! Great blog.
Susan Vinskofski says
Thanks for the extra warnings!
Anni says
Very interesting. I didn’t know that the soap they used to make was harsh because the proportions were off – I thought it was simply the lye itself!
tessisue says
May I copy & print this to hang in my candle and soap shop?
Susan Vinskofski says
Yes, thank you for asking!
Feathered Friend says
Is it safe to use home made soaps on…delicate areas? Should I change the soap recipe at all to use it all over?
Susan Vinskofski says
The soap will be safe for all areas, Feathered Friend.
Connie says
Thank you so much! I am so happy to have come upon your blog. I am a Grandmother of 14 beautiful children and our entire family is getting away from chemicals in our food, out cleaning products, and our personal care products. I have been wanting to make my own homemade soap for a long time. Since going though “the change”, my skin is so dry. I stumbled on a great recipe for a homemade “lotion” and have been using it. It’s works great, but after I shower, my skin is just so very dry and I came to the conclusion it was the soap. I will be getting my list together for making my own homemade soaps. Love this blog! 🙂 Wish I would have had blogs and personal computers when I was a lot younger. LOL Never to late to start!! 🙂
Susan Vinskofski says
Thank you so much for your kind words, Connie. They really encourage me. I’m so glad you not only discovered my blog, but took the time to comment!
Rebekah says
I have poison ivy and someone told me lye soap would help, true or not?
Susan Vinskofski says
I’m sorry not to be able to help, Rebekah, I really don’t know. I do know that tea tree oil helps me with poison ivy and a friend uses crushed plantain leaves. Feel better soon.
Diandra Edwards says
i have tried mixing a soap but it didn’t came out good or right ,instead it separated why?????????plus it also didn’t get hard it have much more coconut oil. what can i do to make this a success i need it for a presentation for the next 2 hours.
Susan Vinskofski says
It’s possible that you did not bring the soap all the way to trace. In that case, put it all back in the pot and keep mixing.
Renee says
Lye is NOT safe for pets who may accidentally ingest small pieces of the soap! I had to take my dog to vet for poison control as he ate a small piece of lye soap that had chipped apart. Lye burns their mouth, esophagus, etc… Also, some natural oils are toxic to pets. Eucalpytus is very toxic to cats. PLEASE BE AWARE of how these items affect our dear pets!
tom says
Eucalyptus is toxic to dogs as well. And i agree, don’t let pets near any bit of these soaps. Some ingredients may attract them as they think it is food item. Good warning
Kristina says
I have been learning about soap making for a while now, but I haven’t yet attempted to make my 1st batch of Soap yet (due to financial reasons currently). I never knew that there were so many people who were so concerned about the Lye, until I started doing all the research I’ve done into soap making.
I’ve seen people say, “I would never use a harsh chemical in my soap like lye, that you have to wear gloves and goggles, and have to be in a ventilated area to make it!” I guess she doesn’t use soap at all, since all soap is made from lye? Lol!
But this article was very well written that explains the saponification process very well! You did a good job! 🙂
Susan Vinskofski says
Thank you, Kristina!
Jennifer Metzler says
I’ve been making homemade soaps for years now. I’ve always thought they were safe to use in outdoor showers that drained to gardens or intentional vegetation, but now I can’t seem to find the research that backs that up. Can you tell me if water from baths will harm vegetation? Thanks!
Susan Vinskofski says
If the soap was made properly and cured, it should not contain any lye.
Larry says
I understand the health benefits of making homemade soap by omitting the chemicals from factory made soap. However, my question is one of cost. Is it actually cheaper to make homemade soap, factoring in the cost of ingredients and the time for curing?
Susan Vinskofski says
Hi Larry! To me, the curing time means nothing since there is no work on my part during that time. The answer depends on the quality soap you are purchasing. To make your own is much less expensive than to buy similar quality soap, but more expensive than brands I prefer not to use. It’s really a matter of ‘you get what you pay for’.
JustSomeOldDude says
For goodness sakes, It’s soap people. ya don’t eat the stuff, or leave it on your skin. It does what soap is suppose to do, clean and kill, that’s it’s Job.
Sometimes i feel like we’re living is a world of SO much information, that people have lost all common sense and have to ask the correct way to scratch their head or tie their shoe strings as adults.
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Kavita says
Any soap, literally any soap cannot be made without lye & other chemicals. these clog skin pores & harsh to the skin. Clogged skin pores cannot breathe & appear larger. These are major causes for forced acne, blemishes, making skin look uneven, old, wrinkled, etc.,
In india We have a body cleanser “ubtan”
Made with different natural, chemical free products which
Exfoliates – dead skin is gently removed & skin is clear
Moisturizes – the ingredients like velli vidhay, vetiver, sandalwood & more makes the skin soft & supple.
Heals acne, dark spots lightens, reduces crow feet, blemishes go away gradually
Bonus – We got rid of soaps from our life. It’s been more than a year we used those.
Major Side effects: Compliments. Photos
Aga says
“(…) And yet, this dangerous chemical is one of the main components of homemade soaps. (…)” This is WRONG. Lye is used in any kind of soap, homemade and store bought, Melt&Pour soap base is made with lye. You won’t find disclosure about lye on store bough soap though, they are using terms like “sodium tallowate” which mean “saponified lye + tallow”, they don’t want let people know they are using lye or animal products in soap. Please fix your statement because this is first information you can find on google search and this is not truth.
Susan Vinskofski says
Yes, sure.
Samantha says
So much to know about sodium hydroxide Soap, love this Info. . Thanks for sharing about this .
Susan Vinskofski says
My pleasure!
MARIE TILLMAN says
I think lye animal dip is the best to wash animals with. I also put it on any bug bites that may happen. I do not make it but I was glad to find 1 place I can still buy it. It does smell like a rotten egg but it wears off quick after the animals get out.