Castile Soap 12

According to the dictionary, Castile is a former kingdom comprising most of current day Spain. There is a special soap variety that originated in the Castile region called … (any guesses) Castile soap. This soap only uses olive oil and sodium hydroxide. This soap was originally made because there was a greater supply of olive oil rather than tallow.

The most commonly used method to make castile soap started with burning plants in the salsola genus (like saltwort or tumbleweeds) and then combining the ashes with water to create the alkaline solution that would convert fats to soap. Olive oil was added to the pot and was boiled. The soap was then forced to float to the surface of the pot by adding a brine to the pot. As the soap was floating, the soap was easily skimmed off and left excess unwanted materials like lye, coloring and other impurities to settle to the bottom of the pot. This created a white colored, hard bar of olive oil soap.

Whoa! Wait just one minute! White soap? I thought last time I looked an all olive oil soap was a dirty green in appearance. The coloring of the soap can depend on the the olive oil you use. Did you know the color of olive oil can vary due to the content of chlorophyll and other similar materials. The color of the olive oil depends on factors such as the fruit ripeness, the olive variety, the soil and climate conditions, as well as the extraction and processing procedures.

Today, I’ll be sharing my experiences with making Castile soap. Not just my good experience, but my not so great experience too!

My first attempt at making Castile soap was about 8 weeks ago during mid-August. I heated my olive oil to about body temperature. (It was probably around 95deg; Fahrenheit.) My lye was about 120° Fahrenheit. I mixed the soap for about 3 or 4 minutes and then decided it was done. I left the batch of soap in the mold overnight. When I came back, I was expecting to have a hard log of soap that was ready to cut. To my surprise, that was not what I encountered. My soap was very soft and cold.

When I asked our Technical Support Team what had happened, I received the explanation along with some chuckles. According to their response, my soap stalled during the saponification process. It did not help that I had only made a one pound batch which does not have enough thermal mass alone to prevent the stalling of the soap. Combining this new information with my low soaping temperatures, I now knew that I hadn’t made my soap well. I asked what I would have to do with my soap. I was told to hide it somewhere and then promptly forget about it for 6 to 8 weeks. I did so by placing the soap (in the mold) in the cupboard above my blog kitchen sink. I programmed an alarm into my phone to check it during the first week of October.

Fast forward to October 4th. I removed the Castile soap from the cupboard and I was very excited to see that it had hardened enough for me to cut the soap easily. I cut the soap log and set it out on a sheet of cardboard to have some more airflow to allow the remaining water to evaporate. By October 6th, the soap was hard enough that I could package it for shipping samples. I promptly packaged the soap for samples and then moved on to analyze my successful batch of Castile soap.

Collect needed items:

Olive Oil
Sodium Hydroxide
Soap Spoon
Rubbermaid Drawer Organizer #2915
Immersion Blender
Time spent:
Weighing time: 3 minutes
Adding lye to water: 15 seconds, followed by 60 seconds of stirring
Heating of Olive Oil time: 90 seconds
Pouring lye solution into the Olive Oil: 10 seconds
Using immersion blender to mix soap solution: 10 minutes (Using blender every other minute)
Pour into mold: 30 seconds
Allow soap to rest: 24 hours
Recipe in ounces:
32 ounces Olive Oil

4.12 ounces Sodium Hydroxide
12 fl oz water

Finished soap after bagging for samples.

Olive oil after being weighed.

Adding the lye solution to the olive oil.

Blending the raw soap to reach trace.

Continuing to mix the raw soap.

Pouring the raw soap into the mold.

I was determined to make sure my second batch of Castile soap succeeded. This time, I increased the temperature of the Olive Oil to about 130° Fahrenheit and my lye solution was about the same temperature. I used my immersion blender and mixed until everything appeared to be mixed completely. Once I reached this state, I let the raw soap sit for a moment and spent 1-2 minutes cleaning the kitchen, packaging samples or formatting other recipes. I did this several times until the temperature of the raw soap increased and seemed to be holding at a steady temperature. At this time, I poured the raw soap into a wooden mold lined with a plastic bag. I thought that the wood mold was going to be my best friend for its insulating properties. I used a different style of the Guerrilla Mold from Dirk’s post. Allow to sit until soap is firm.

The next morning I was able to cut my soap into bars. Stack to allow good air circulation. Allow to cure for several days before using. Longer curing will result in a harder bar.

Lots of various information has led me to think that Castile soap is like good wine or cheese. Most of the time it needs aging before it is a fantastic product. I have been told that Castile soaps can be slimy and snot-like in their first year, but the texture and lather improves after a year of dry storage. A year? I don’t know about you, but anticipating soap sales a year in advance seems impossible. I think a 100% Olive Oil soap is nice, but Coconut or Palm Kernel are great additions to making a good soap better.

Remember, if your Castile soap is soft after 24 hours, you will have to leave it in the mold and wait 6 to 8 weeks! This thought alone is enough for me to increase my soap temperatures and use a wood mold. Then again, sometimes I want to poke things when I’m supposed to leave them alone!

The Castile soap samples have been sent to the Shipping Department to send out in orders. I really want to hear your comments about this or any of the other recent soaps. I hope that anyone wanting a sample soap will request one and if we have any samples we will send them to you.

This has been a very interesting process and I think I’ll probably try it again. I hope this was as educational for you as it has been for me. This is one soap that I wonder if a Hot Process Castile soap would be any easier. Have you tried this before? I’d love to hear what you have to say!

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Castile Soap, 5.0 out of 5 based on 1 rating

About Andee

Director of Happiness. I'm a thirty-something soap snob. I've grown up with handmade soaps, and I love them! I really like making lotions, soaps, and perfumes. I adore mixing scents to come up with something new. My favorite scent is either Wicked or Cotton Candy. I tend to hoard fragrances, I even have an Earl Grey Tea from the MMS catalog. I won't tell you how old it is, but it sure is good!

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12 thoughts on “Castile Soap

  • SilverFirsFarm

    I ley my castile cure 6 months… its one of my best sellers and my customers expect it! Its not hard to anticipate.. I just make one batch every month, date it, and set it to cure. That way, every month there is a new batch of castile ready for my customers! It truly does improve with time… the longer the better. I have a few prized bars of a three year old batch, just as wonderful in color as the day it was cut- but hard as a brick and such creamy, tiny bubbled lather.. its heaven!
    Castile’s not for everyone.. some of my most successful bars are comprised of mostly olive oil though. Time and time again customers come back for it because it is the only bar I’ve made that they all say has worked for them, when nothing else does.

    PS I’ve never had to increase my soap temps or anything… i keep my lye at room temp and oil at room temp too.. I so use a wooden mold though. My castile gels in about 4 hours.. and if I dont cut within 24 hours it can be too hard. I do a water discount… maybe thats the difference? Interesting!

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  • diana

    I haven’t made castile bar soap before. I was however successful making a batch of liquid castile soap three months ago and it is very different to work with than any other liquid soap I’ve made. It’s excellent on sensitive skin, whether that be from hard water or just plain needing some tender loving care. It doesn’t suds up much, but you can add something to it to increase the bubbles, or make peace with the nature of the soap and enjoy it for it’s wonderful properties. Having tried several different dog shampoos, I now bath my seven month puppy in liquid castile soap and refuse to use anything else on him. His skin doesn’t flake or get itchy even a month or two later, and his fur is so incredibly soft and clean, it’s just wonderful.

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  • bluebutterflz

    I am excited to try this recipe. How simple! Plus I live in a very organic all natural town so this will definitely prove successful! I had a question, I’m thinking of making two versions of this one “true castile” and another with maybe some coconut oil and maybe palm(Give it more suds). Any suggestions on how much to add to still make it a mostly castile bar?

    Oh and I would be VERY interested in learning how to make this hot process! Just imagine how much time could be cut if it was done this way!

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    • Andee Post author

      Most soaps labeled Castile in the Castilla area are 75% olive and 25% tallow or coconut. Tallow being traditional. I think this with coconut oil with be fantastic.

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  • bluebutterflz

    Hi, I just had to update that I made this soap using this recipe and it was a HUGE success! It’s already a nearly white and surprisingly hard bar! Not to mention soooo quick to make! Tomorrow I hope to try this with a bit of coconut oil for extra suds! Thanks again!

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  • meadows

    I wish I could get my castile soap to be ready to cut in 24 hrs. I have made a few batches and all were soft for a month or more. The last batch I made I did a water discount using the same lye and water amount. 4 days and still too soft to cut. LOL!! But I love the castile soap.

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  • Jaya

    I make castile every year… one large batch, because I age mine for three years before use.
    As my Hubby called it..’leap-frogging through time’…can you tell we are nerds?

    I use it as my facial/medical (wound cleaning) soap, and ‘When Allergies Attack’ – it’s lovely. I make other soaps all the time, but Castile is special.

    My last batch, done last week, is still soft. This hasn’t happened before, but I believe it’s to do with where your olives are grown, the particular batch etc etc. I tested by making a bastille with some other hard oils today, and it’s still soft after 10 hours. So I’m gonna say it IS the olive oil batch. The weather has been strange here in Australia lately and it’s this year’s crop, cold pressed extra virgin, like I always get. And I water discount heavily.

    That’s the way it goes! Just have to wait a couple of weeks/months before unmoulding.

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    • Tina

      Olive is slow to firm. This is why we generally increase the starting temperatures when making 100% olive oil soaps. I suspect you will need to do that. I would not wait 3years for this batch, it is more likely to turn rancid.

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      • Jaya

        Hi Tina!

        I think it’s gonna be fine… it suddenly went rock hard, and unmoulded beautifully… for some reason it just took that much longer. I was speaking to a castile soaper in Greece, and she said that she’s had random batches that do this. She thinks it’s the olives as well.

        Anyway, it’ll get the sniff/wash test every month, like I always do. Every batch, I designate one bar that gets small pieces chipped off every month, and tested. The bastille test batch is getting much harder, much quicker than the castile, just softer than usual at this time remove from batching…

        All part of the fun!

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  • Jaya

    Before you ask, yes I DID wait three years to use my first batch! It’s like my superpower, or something.

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