Introduction: Make "Lye-Free" Liquid Castile Soap From Your Kitchen

Picture of Make "Lye-Free" Liquid Castile Soap From Your Kitchen

This particular recipe is a base process to start making your own liquid castile soap from home.  It is repeated in several articles, books, and internet sites as being “lye-free” However, please keep in mind that all soap has had some form of lye in it at one point or another (if you can find a recipe that is completely “lye-free” during the WHOLE process we would like to know).  The goal here is to remove all the lye during saponification so you will not have any left in your final batch.  We want you to feel free to experiment with different oils however, to keep it “lye-free” use the measurements of the oil, water and KOH (potassium hydroxide) as stated below.

Step 1: Materials Needed

Picture of Materials Needed

*  47 oz organic olive oil (technicallycastile soapis only made from olive oil but, feel free to try something completely different)
*  32.9 distilled water
*  9.39 oz KOH (potassium hydroxide)(where we get ours)
*  (Later at dilution) 80 oz of distilled water

(all pots, spoons, bowls etc. make sure they are stainless steel and/or heat safe)

*  Slowcooker (one that you will only use for soap, do not use again for food)
*  Accurate scale
*  Stick blender, immersion blender
*  Large stainless steel pot
*  Spoons
*  Bowl(s)
*  Vinegar
*  Gloves
*  Goggles
*  Hat
*  Containers to store your soap
*  Notepad and pen

Make sure you can set aside enough time during the day to give attention to your project without any distractions (easier said than done), have all of your materials ready to go, and ingredients already measured in safe and covered containers.

Step 2: Remember the Movie Fight Club? Yea…they Were Using KOH

Picture of Remember the Movie Fight Club? Yea…they Were Using KOH

Intended for educational purposes only
Image source Fight Club. Director David Fincher. 20th Century Fox, 1999, film
(Click here if you do not see animation)

First Aid for KOH

If KOH is in contact with your skin, first treat the area by rinsing with vinegar and then water for 10-15 mins.  Contact with the eye can cause severe damage and even blindness so, it is great to keep an eyewash solution nearby in a squirt bottle (can be made of distilled water or a sterile saline solution)  Rinse infected eye out with the eyewash solution for at least 10 mins.  Have a phone nearby with the number to poison control center ready.

Find a local center near you

National Hotline 1-800-222-1222

Step 3: Waiting on Naptime...

Picture of Waiting on Naptime...

Keep children and pets away from your work area and make sure the room is well ventilated.

Step 4: "Suit Up"

Picture of "Suit Up"

You will be working with lye and an immersion blender so, we recommend that you wear long sleeves, a hat, gloves and goggles during the complete process.

Step 5: Warm Up

Picture of Warm Up

Okay, Let's Go!

Start with 47 oz of olive oil in your slowcooker with the setting on low.

Step 6:

Picture of

In a stainless steel pot, fill with the 32.9 oz of distilled water and place it on a heat safe surface. Get ready to pour the 9.39 oz lye into the water. Repeat: pour the lye into the water, DO NOT pour the water into the lye!

Step 7: Go Slow

Picture of Go Slow

Pour very slowly and be careful that you do not splash the mixture around or breathe in any of the vapors that begin to rise up.

Step 8: Lye Into the Oil

Picture of Lye Into the Oil

Slowly pour the lye/water mixture into the slowcooker and stir with your heat safe spoon.  It’s really cool watching the oil become cloudy when you add the lye.

Step 9: Stir Forever

Picture of Stir Forever

Use your immersion blender to stir, stir, and keep on stirring. This is where you put all the work into it. Don’t give up and be careful of splashing.

Step 10: Trace

Picture of Trace

In about an hour and a half you should have it at such a thick consistency that it seems to “trace” the path of your mixer.
Once your soap is at this point we need to let it sit and do its thing. Put a lid on it and in every 20 mins,  slowly stir it back up.

Step 11: Thickening

Picture of Thickening

Your mixture is going to get thick (kinda the point) so go ahead and put up the immersion blender and use your heat safe spoon from here on out.  Besides, using the blender at this point will only add more oxygen and cause the soap to fluff up.

Step 12: Keep on Going

Picture of Keep on Going

You want to get it to the point where it is translucent and thick and this may take a couple of hours of getting up and down to check on it. Be patient…

Step 13: Testing

Picture of Testing

To test your base to see if it is ready, pour 1 cup of hot water into a glass and stir in a small sample of your paste.

Step 14: Can You Read It?

Picture of Can You Read It?

If you can still see thru your glass then it is ready otherwise, chill out and let chemistry do its thing.

Step 15: Transfer

Picture of Transfer

After you have tested your paste, place it into your large stainless steel pot.

Step 16: Dilution

Picture of Dilution

We are going to add a total of 80 oz of hot/boiling water on top of the paste and GENTLY stir the water in (just a little bit).  Cover the pot and let it sit overnight to settle.  You want it to calm down and slowly dissolve into the water

Step 17: There You Go...

Picture of There You Go...

Congrats to you!!!
You should have woken up this morning with your own homemade liquid soap:)  If you want to make sure that the soap is fully cured and the lye is no longer active, wait 3-4 weeks before use.

Once again this is only a basic liquid castile soap and it is a great place to start.  From here you can experiment with scents, oils, dilution etc…

Open Source Soap Co.
OSSC is starting from the beginning to develop a liquid base soap that is versatile in your home, easy on your wallet and kind to our environment.  We are testing, documenting and sharing our process along the way because, we believe that everyone should have the right to know what is in their products and how they are made.

Basic "Lye Free" Liquid Castile Soap
-An all around great basic cleaner with only 3 ingredients used.  Great start for beginners.
This is a from scratch recipe that uses KOH potassium hydroxide lye and should not be attempted unless you will take it seriously and follow all the safety precautions.

Next project?

Foam Pump Mason Jar Soap Dispenser
Create your own foam pump mason jar soap dispenser from material that you may already have in your home.  Did you know that the foam soap that you buy at the store contains mostly water? And that it is actually the pump itself that creates the majority of the foam? Save yourself some money by diluting 6 parts water to 1 part of your favorite liquid soap


jessyratfink (author)2013-04-08

This is a fantastic tutorial - I did soapmaking for the first time recently and it was awesome. :D

Love all the gifs!

OSSC (author)jessyratfink2013-04-08

(blushing) Hey thanks so much, and it is greatly appreciated :) I have also found that soapmaking is a lot easier than what I first imagined yet, it still offers that right amount challenge to make it the best that you can. We will post more in the future, the plan is to publish as we go (dish soap, hand soap etc).
Good luck on your future endeavors with soap as well :)

SuzanneW17 (author)2016-03-30


I've found it always best to run your own lye calculations to avoid many of the complaints I see posted. When I ran lye calculations, I found the following:

Oils: 48 ounces

LYE KOH (Potassium Hydroxide): 259 grams (its always best to use grams to measure your lye)

Water (to mix with the LYE): 18.24 ounces (517.09 grams or 1.140 lbs)

Here is a soap calculator to use. Its not the only one, but the one I prefer:

I've not yet made this recipe, so I'm not sure how much water will be required to fully dilute the resulting soap paste, so I'll start with the noted 80 ounces and see if I require more or less.

My experience is mostly with Cold Process (CP) soap making, and have just started playing with liquid soap making. Its different, but still just as interesting and enjoyable as making bar soap.

CreativeGeek (author)SuzanneW172016-12-07

I went ahead and played with the calc a bit.

KalyneC (author)2016-02-05

You use KOH, so how come it is lye free? ;)

CreativeGeek (author)KalyneC2016-12-07

No lye in the end product after the reaction process.

Goddessa Brique (author)2016-08-18

thanks for this fantastic and amazing tutorial. i have bookmarked it for reference.

I tried my first liquid soap testerday but it didnt turn out great at all. First, i got kOH from a local market in Nigeria where it is referred to as Caustic potash. when i mied it in dilution water, it didnt sizzle or fume or get hot or anything at all. it was just like adding salt to water. the water didnt get clear too and had some impurities in it.

I went ahead and added it to my oil miture anyways and the disaster began. Nothing happened at all. It was just like i added water into oil and even after heating and stick blending it for a while, it didnt emulsify nor did it begin to thicken. my measurement was;

coconut oil 500ml

olive oil 500ml

castor oil 250ml

koh 9oz

water 27oz

even after leaving it over night, i had a bowl of oil seperate and sediments below whuch i drained out eventually. I dont know what to do, i followed a strict measurement and niw wim so skeptical about trying again for fear that id waste money again and get similar result at least until i can be sure about what i did wrong.

RCS1 (author)2015-11-23

I'm sorry, this does not use lye because, it is implied lye is bad, but you're using CAUSTIC SODA? How is that not as dangerous?

At least you can buy food grade lye...


SuzanneW17 (author)RCS12016-03-30

to make any soap you must have lye. Its chemically required for the Saponification.

Saponification is the chemical reaction between an alkali (lye) and a fat or oil to form soap. If you read the post you'll see she says "lye-free" is the status of the liquid soap after the entire process has completed. Left over lye would burn or irritate the skin.

SusanW79 (author)2016-02-07

I was so happy with this recipe until I awoke this morning to find a thick gelatinous mess. Some of the castile soap may be pourable, but most too thick to stir. I assume boiling water and adding it to the pot is the answer. I looked through the questions below, but I don't see where you answered that question asked there.

ArielM25 (author)2016-01-14

I made liquid soap with this recipe and it's true, reaching trace was a very very long process. It happened after over 2 hours stirring when I had almost lost hope. I had a different problem though. The hot boiling water added to the paste at the end, the 80 oz, were not enough to dissolve the whole paste. I had to add more water. It looked like the first water got absorbed by the paste. Did any of you experience the same issue?

thrutrees (author)2015-06-07

I just want to make sure I'm understanding Steps #9 & #10 correctly....Stand there and stir constantly for 1 1/2 hours holding a stick blender? I don't know a lot of people that have that kind of arm stamina so I just wanted to make sure.... Thanks for the tutorial.

LucieN2 (author)thrutrees2015-12-22

Well a stick blender stops working after 20 minutes because the engine gets too hot, so I was wondering about the same thing ? I make soap every month and I never have to stir more then 15 minutes.

jeevana03 (author)2015-11-08

Tried the recipe as given.But despite of continuous stirring for almost 2 hrs,it didn't reach trace.May i know if anybody faced similar problem or If it was a success to anyone,pls mention the workable steps

LucieN2 (author)jeevana032015-12-22

Your mix probably got too cold before saponification. Try to reheat it.

LucieN2 (author)2015-12-22

Thank you for the tutorial. I would like to mention it's much safer to use a soap calculator instead of just using someone else's calculations.

If I understand this well, you are using the hot process and you add the extra water after your soap got through the gel phase? I have to say I have never made a batch I had to stir for more then 15 minutes, so I'm quite surprised by time times mentioned and I'm unsure about the point of adding the extra water.

Bethahearn (author)2015-08-10

how many oz's does this receipe make?

JosefineB (author)2015-08-06

MeganM5 (author)2015-05-27

I am on my second batch of failed castile soap. My first batch separated into oil and crumbly, dry chunks before it reached trace. My second batch made it to trace, but when I left it to cook on low heat, it had also separated into oil and crumbly, play dough-like chunks when I came back to mix. Am I over mixing? Over heating? HELP

MeganM5 (author)2015-05-27

JohnnieB1 (author)2015-03-11

yes it is made with lye but the lye is spent out by converting the oil to soap and is no longer lye , if you use only enough to lye to convert the oil then its all gone-- lye free

sissysetser (author)2015-02-04

OK, I am either overlooking it or don't know math very well, but how many ounces does this particular recipe make in the final end?

sissysetser (author)2015-02-04

OK, I am either overlooking it or don't know math very well, but how many gallons does this particular recipe make in the final end?

ThomasP5 (author)2015-01-13

I found these directions from 1833 on how to make soap.

ThomasP5 (author)2015-01-13

I found these directions from 1833 on how to make soap.

ThomasP5 (author)2015-01-13

I found these directions from 1833 on how to make soap.

lsandy made it! (author)2015-01-12

Your Instructable Rocks! Batch #2, using Distilled Water, only took two days two cook, dilute and jar. DEFINITELY use Distilled Water! The soap remains clear, is very gentle, and works great. My 14-year old son succintly said, "That's really nice." That is high praise from a boy who grunts and mumblesthese days. I will sequester this batch for 3-4 weeks before I prepare and replace all the household soaps, shampoos, and cleaners. Batch #1 will be used as a laundry detergent and in household cleaning products. Thanks again.

lsandy made it! (author)2015-01-11

Thank you for this instructable. The best advice you gave was to be patient. I won't lie, but it took me four days to get finally have diluted soap ready to go into jars. I have been sequestering the soap for about two weeks as the liquid turned a little cloudy after a couple of days in the jars in a cool, dark place. Everything I have read since says the soap is still good. This was my first batch, and I used tap water. I have a second batch cooking as I type this, and I used distilled water instead of tap water, to see if it shortens the total production time and yields a clearer liquid soap. I will keep you posted. Thank you again. (author)2014-12-29

I can't wait to try this! I've been doing tons of research, and I like the instructions the best on this site. One question: is a neutralizer needed? I saw several recipes that added boric acid. Dr. Bronner's uses citric acid. Any thoughts?

I have to comment on the responses about the lye. I read through it carefully, so should everyone: The soap is "lye-free," meaning none remains after the process is complete!

Thank you! I can't wait to get started!

Whitehilldairy (author)2014-12-28

Has anyone made this with Goat Milk instead of water?

peter.caravella (author)2014-09-03

Just so you know...Potassium Hydroxide is basically this really isn't Lye-free soap. Not that there's anything wrong with using Lye or Potassium Hydroxide. Both are excellent components to cleaning agents.

It evaporates. That is how it becomes Lye-Free

stacee.magee.1 (author)2014-11-19

This is not LYE free, KOH is lye...

The KOH evaporates thus leaving it 'Lye-Free"

farmerdevon (author)2014-11-09

I sure hope you might still be answering questions. We made a batch of the liquid castile soap yesterday and everything looked perfect throughout all the steps (although getting to trace required more time and turning up the crockpot heat). That said after testing and then adding the last water addition and letting it rest overnight, only about 20% of the volume is beautiful perfect castile soap, while the rest "soap base" remains a relatively undissolved gelantious mass. I have tried heating and so far added about 6 cups of hot water, but the mixture is still far to thick and "unhomogenized". Please help me!!!

Try_Natural (author)2014-10-10

My recipe work up to step 11. how long it took to get to step 12? did you stir slow? mine after 14 hours was no chance translucent.

Try_Natural (author)2014-10-10

I made this..but failed. it cooked for 14 hours until smelled burned and no way of getting the test water is just mily :( i did all by the

peter.caravella (author)2014-09-03

I'm also not sure why in the world you'd use a slow cooker. I used to be an Extension agent for the University of WI and taught a very popular "Slow Cooker class." Every time your remove the lid from the slow cooker you set the "cooking" time back by another 20-30 minutes. I would think a faster, shorter process would be to low-boil the product in a pot on the stove, using a double-boiler or microwaving the product. Just a thought.

As a soapmaker, I can tell you this is NOT lye free. potassium Hydroxide or KOH is a lye derived from wood ash. also known as potash. Sodium Hydroxide NaOH is the Lye commonly used in hard soaps. Both are caustic and highly hazardous. KOH is what our ancestors made from leaching rain water through wood ash. the "lye soap" made from potash was a brown liquid goo. looking at old recipes it would say to "throw a handful of salt" into the pot if you wanted to pour hardened bricks. Salt is Sodium and what is not commercially made as NaOH.


off my soapbox now.

Please note that lye-free is in quotes in the title. Also, read the first paragraph for an explanation of what "lye-free" in quotes means for this instructable. ;)

keglarek (author)2014-05-24

Those made with saponin contain absolutely no lye

randomprojectguy (author)2014-01-21

potassium hydroxide is just as like sodium hydroxide aka lye

AudraC (author)2013-08-03

I'm assuming the olive oil and water are measured in fluid ounces. Is this correct? Is the lye measured in weight?

OSSC (author)AudraC2013-08-04

For small batches in the crockpot, you can use the same scale to measure the water, oil and the lye. Oil weighs more than water but, that would really only be an issue if you were making very large batches. Keep it simple with this recipe :)

sunshiine (author)2013-04-10

I have been wanting to try to make castile soap. This is such a great write up and your images are totally awesome! Thanks so much for sharing and do have a splendorous day!

OSSC (author)sunshiine2013-04-10

Thank you so much for all the wonderful encouragement and I am so glad that you enjoyed it. This tutorial is the first of many, and it's a great starting point for those who have never tried making soap before.
You have a splendorous day as well, sunshiine :)

About This Instructable




More by OSSC:Foam Pump Mason Jar Soap DispenserMake "Lye-Free" Liquid Castile Soap from your Kitchen
Add instructable to: