# Recycled kitchen oil for liquid soap



## Silvia Stieger (Nov 1, 2018)

Dear forum members, my question is if I can make Liquid Castile Soap with used kitchen oil (mainly sunflower oil, KOH as reaction agent)?

Any experiences that differ from classic Castile soap making?
Important dos & donts ?

Thank you in advance for sharing knowledge


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## jcandleattic (Nov 1, 2018)

Castile by some definitions means using 100% olive oil, so there's that difference. 
But also, you would run the risk of the oil going rancid, having foreign particles, and "ickies" in it from the prior use, and most likely not having the best smelling end product. 

However I've never used recycled oils before so the end product scent is just a guess.


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## shunt2011 (Nov 1, 2018)

As stated above, Castile is 100% Olive oil. You will likely need to clean your oil before attempting to make soap.


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## DeeAnna (Nov 1, 2018)

Yes you can make liquid soap from recycled cooking oil. You may want to wash the used fat with water to remove some of the residues and chemicals that cause unappealing odor and color. Here are some ways of doing that:

https://www.soapqueen.com/bath-and-body-tutorials/tips-and-tricks/render-lard-home/
https://www.soapmakingforum.com/threads/rancid-old-olive-oil-on-soaps.61303/

Would this be "castile" soap? In the sense that soap makers use the word, the answer is no, because the classic original castile is 100% olive oil soap. But in the broader commercial sense of "castile" to mean any vegetable oil soap, then yes.

There's not a great deal of difference between any veggie oil soap and a 100% olive oil soap as far as making it, regardless of whether you use NaOH or KOH.


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## Silvia Stieger (Nov 2, 2018)

Thank you for your answers, I will try out!

Another recycling question:
Any experiences replacing KOH with Ash (wood Ash or banana peels & leaves Ash). I live in the tropics so it's an option with the banana residue material.


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## BattleGnome (Nov 2, 2018)

I think the problem with using ash is getting the fires hot enough for the appropriate chemical reactions. I’ve never tried it but it might be something to check into before you start


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## DeeAnna (Nov 3, 2018)

Wood ash lye would be mostly potassium carbonate, not potassium hydroxide, and a carbonate lye is harder to use to make soap. You can react the wood ash lye with slaked lime to convert it to the hydroxide. You'll  want to test the concentration of either type of lye before use.


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## earlene (Nov 11, 2018)

Perhaps some members in your part of the world have used ash in soap making.  I haven't read of many in the US here on SMF who actually do, probably because access to the more reliable chemical versions are so readily available.  I do believe there is at least one member here who knows how to and may make true African Black soap using ash, so maybe you will get an answer should she see your question.


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## Silvia Stieger (Nov 14, 2018)

yes black soap, I heard about it. but its produced in Westafrica.

anyway, I realised that making ash lie is more easy to replace caustic soda to do hard soaps.
but to replace KOH it seems quite a mission and I want to do liquid soaps.
unfortunately I only found out this after burning many banana leaves ... 
beginner mistake I guess.
Anyway, after quite a mission of a search I got nicely packed KOH here at the kenyan cost.


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## shunt2011 (Nov 14, 2018)

Wood ash lye is KOH not NAOH.  Both are considered caustic soda.   So you are not correct in your statement.  Ash lye will make soft soap with NAOH.  Better suited for Liquid soap.


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## DeeAnna (Nov 14, 2018)

Wood ash lye is a solution of water and mostly potassium carbonate (K2CO3). An ancient name for potassium carbonate is _potash_.
Wood ash lye reacted with slaked lime turns into potassium _hydroxide_ (KOH) with the common name of _caustic potash_.

Sodium carbonate (Na2CO3) has the common names of "_soda_" and washing soda.
Sodium hydroxide (NaOH) has the common name of _caustic soda_. 

See how the term "caustic" is applied to the hydroxide alkali, but it's not in the name for the carbonate alkali?

You don't hear the names potash, caustic potash, soda, and caustic soda too much in North America, unless you're working in the industry. The common names are more often used in other countries from what I gather from posts here on SMF, but as you can see it's very easy to get the common names confused. Better to use the chemical name to avoid misunderstandings.


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## Silvia Stieger (Nov 15, 2018)

thank you for that input.
You mentioned the slaked lime method before. And I really tried to find a workable method but no success.
I ended up finding some more complicated distillation methods 
And some information I found on the net are just wrong (and I unfortunately don't have a book on that, don't tell me to buy one on Amazon)
I also went for example thought some posts of this forum but no success:
*Re: Making Soap From Wood Ash Lye*
« Reply #1 on: January 28, 2013, 02:59:20 PM »
http://en.wikipedia.org/wiki/Soap_making#Soapmaking
http://www.alcasoft.com/soapfact/history.html
http://www.cavemanchemistry.com/projects.html
http://www.cavemanchemistry.com/cavebook/chsoap.html
http://www.ehow.com/how_5700913_make-potassium-hydroxide.html

I just want to say that I tried...
So, do you have any practical input how to turn banana leave ash to KOH? With quantities and how to do it.
As I said, I meanwhile found commercial KOH to buy. But I am wondering how to do it by now.


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## Sk8rTips (Nov 15, 2018)

Curious if you had any updates / attempted the used kitchen oil? It's something I hadn't thought of but since reading your post the other week it feels wasteful to throw it away. Hmmm


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## Silvia Stieger (Nov 18, 2018)

yes, I am on it and will post when I have an outcome. i know it works for soap bars.
yes, would be great to recycle the oil rather than throwing it.


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