Make "Lye-Free" Liquid Castile Soap from your Kitchen

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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.

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Step 1: Materials Needed

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*  47 oz organic olive oil (technically castile soap is 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.
This is a fantastic tutorial - I did soapmaking for the first time recently and it was awesome. :D

Love all the gifs!
OSSC (author)  jessyratfink1 year ago
(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 :)
JohnnieB118 days ago

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

sissysetser1 month ago

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?

sissysetser1 month ago

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?

ThomasP52 months ago

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

ThomasP52 months ago

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

ThomasP52 months ago

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

lsandy made it!2 months ago

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!2 months ago

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.


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!

Has anyone made this with Goat Milk instead of water?

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

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

The KOH evaporates thus leaving it 'Lye-Free"

farmerdevon4 months ago

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_Natural5 months ago

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_Natural5 months ago

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

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. ;)

keglarek10 months ago
Those made with saponin contain absolutely no lye
potassium hydroxide is just as like sodium hydroxide aka lye
AudraC1 year ago
I'm assuming the olive oil and water are measured in fluid ounces. Is this correct? Is the lye measured in weight?
OSSC (author)  AudraC1 year ago
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 :)
sunshiine1 year ago
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)  sunshiine1 year ago
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 :)