# Recycling project - used cooking oil saponification



## marcoslick (Feb 19, 2012)

Hello everybody,
as I am new in this forum, my name is Marco, newbie soapmaker.

I am involved in a recycling campaign and as I made just my first two batches of soap so far, an idea came in my mind, making soap from used cooking oil...
I am not an expert and for sure somebody tried this before me,
does anybody have more info about making soap from used cooking oil, the oil from deep fryers to be more precise?
the fact that it has been kept at high temperatures for long time and the interaction with food in cooking process may have changed the structure of the oil, saponification is still possible?

This is for a recycling campaign I am trying to improve in the area where I live, I hope everybody can share some info to help us helping the environment.


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## Fragola (Feb 19, 2012)

It will be a lower quality soap (but still soap). That cooking oil is still 99% oil. 

Somebody was telling me a long time ago they used only cooking oil/fat, but that was for making laundry soap. Have you considered what would you use the soap for ?

Your first issue will be determining the saponification value, since cooking oil may be a mixture of oils with different saponification numbers. 

Also, there's a method of purifying the oil, using salt and/or baking soda, which I use sometimes myself for old, expired oils. It does not work miracles, but some improvement does happen.


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## marcoslick (Feb 19, 2012)

The soap could be used for skin, but just if I make sure that is not harmful for the good health of the body, otherwise I can still make it for laundry...

The saponification value is a hard point..
..assuming to use only cooking oils that specify kind and percentage on the lable, the problem is to determine if the cooking process changes the saponification values...does anybody know about any research or scientific datas about that?

Fragola could you tell me more about this method for purifying the oils?
And what do you mean with expired oil? does an oil expires?


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## green soap (Feb 19, 2012)

I made my first soaps using recycled oil, and re-purposed oil.  This is how I got into soap making.

Now a days I use only new oils in my bar soaps, but I still have a soap I made a year ago with 80% recycled oil and it is good.  My soap formula has improved so it is not as nice as the soaps I make now, but it is not spoiled or rancid.  I did not even scented it, which now I feel it was a brave thing to to, recycled unscented soap!

I knew I was dealing with 100% soy oil, so the saponification value was not a mystery.  I filtered it twice, before and after I deodorized it.  I deodorized it by bringing it to frying temperatures and frying a few plain skinned potato slices.  Others recommend frying a few ginger slices.  Let it cool, filter again.  If you have a shop, you can heat the oil under vacuum and run steam to carry the odor particles away.  Most of us don't have these facilities in our garages.

I am using my own used recycled oil to make soap for our own laundry, liquid hand soap and dishes now.  

One recommendation I have is to use a minimum of 25% hard oil, and that would be either palm kernel oil or coconut oil, or a mix of both.  Do not use crisco.  The reason is that most cooking oils will result in a soft bar that does not lather a lot and is very mld but not very cleansing compared to other soaps.  It will still get you clean though.  So the percentage of recycled oil will be 75% max.  Still very much worth doing.

Here is a soap made with more than 50% used cooking falafel oil.  I have tried to contact them with questions but they have not answered.  If ou get any answers from them, please share!

http://apokalypslabotek.se/the-soap/


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## Fragola (Feb 19, 2012)

No, the saponification value doesn't change during cooking, problem is they sometimes mix oils with different SAP numbers for cooking. In that case, maybe it would be easier to start with liquid soap.

Yes, expired, as in old, rancid.

I've read about 2 methods of purification:

1. One involves mixing the oil with a 10% hot water/salt solution and separating the oil from the solution. The separation is a little tricky, in fact I got some water in the oil, which slightly increased the superfat, but not a big deal. 

2. Second was suggested by another forum user, adding some commercial cleaning powder. Found the link:
http://www.soapmakingforum.com/forum/vi ... 33408262f9

I ended up customizing the first method for a dry run (which means adding salt/baking soda powder).

Thinking about this again, I'm getting some new ideas: magnesium silicate is talcum, but maybe other powders can be used, like clay or activated charcoal.


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## carebear (Feb 19, 2012)

you may be able to temporarily deodorize it, you cannot make old oil fresh by any means, so if you make soap with used oil you risk rancid soap much earlier than would happen if you use fresh oils.

if you know exactly what oils and in what proportion then you can calculate the SAP.  

if you are collecting from restaurants, be aware that the oil may have nasty contaminants in it, such as degreaser used to clean with.  i don't recommend it.


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## Guest (Feb 19, 2012)

Used cooking oil isn't really a problem for the environment. It isn't toxic and poses no problems if it is landfilled. The bulk of the used cooking oil from restaurants is now recycled into biodiesel.

Used motor oil, on the other hand, is a problem, since so many DIY's don't dispose of it properly. You should try making soap from that.


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## Fragola (Feb 19, 2012)

Used cooking oil is a problem for the environement, as long as you're making soap from pristine fresh oils 

You can't make soap from motor oil, that one doesn't saponify.


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## ChrissyB (Feb 19, 2012)

Sorry but I have just go to say...


YUCK

 :shock:


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## Guest (Feb 19, 2012)

Fragola said:
			
		

> You can't make soap from motor oil, that one doesn't saponify.



But have you tried ? I mean really tried? I mean, do you love this planet, or what? :wink:


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