Cleaning used cooking oil for soap making

Mari33anne · Sep 18, 2013

Hi all,

I have the opportunity to get for free used cooking oil from the university and hospital kitchens locally and would like to recycle this oil into soap bars.

Anyone knows how to clean this oil ? I get it into barrels ( abt 100 Lbs per barrel), the oil is already sifted through a sifter and all solid residus removed. I would like to "neutralize" the oil then use it for soap making.

Some people talked about removing the glycerine some others suggested to "hide" the cooking smell etc... wonder what would work best to make this oil "useable" for soaping.

Any suggestion taken thankfully.
Cheers
Marianne

judymoody · Sep 18, 2013

Given that the oil has been subjected to sustained high temperatures, it is likely to oxidize more quickly in soap. I would be hesitant to use it unless you are going to use the soap within a short timeframe.

OliveOil2 · Sep 18, 2013

I have never done this, however here is an interesting article from one of my favorite soap making sites:

http://www.japudo.com.br/en/2013/08/16/used-cooking-oil-soap-why-not-be-a-first-class-soap/

Do you know what type the oil is? It may be a blended oil, but in any case hope the above article is helpful.

sistrum · Sep 18, 2013

What Judy said.

Mari33anne · Sep 18, 2013

Thank you Judy, thank you Olive.

Judy "Given that the oil has been subjected to sustained high temperatures, it is likely to oxidize more quickly in soap."

While perusing this forum I sumbled over this " http://www.soapmakingforum.com/showthread.php?t=9163 " and Donniej seems to be hitting the nail on its head, he really is into this thing and I now just hope if he would show up or shime in this discussion or anyone knowing how to get in touch with him.

OliveOil2, thank you for the interesting link, indeed it shows that used cooking oil can be processed and turned into oil.

Cheers,
Marianne

judymoody · Sep 18, 2013

I enjoyed reading that post about reclaimed oil. However, it doesn't say anything about shelf life. As cooking oil is usually soy or canola to begin with (both prone to oxidation under the best of circumstances), I'd still be leery. While I applaud the desire to recycle raw materials, I am also concerned about possible waste of additional materials (lye, fragrance, color) if the soap goes bad before it can be used.

By all means try a small batch and see what happens. The cost to you would be low.

Donnie J hasn't been on the forum for quite some time. You could try sending a PM.

neeners · Sep 18, 2013

there's a company on the island who turns the used cooking oil into bio-diesel, and then hast glycerine leftover at the end. he makes soap with that. not sure what kind of oil he uses (the bf got some bars, but he doesn't know to ask such questions....)

green soap · Sep 18, 2013

The recycled oils I have used were used to deep fry only once, so they were fairly 'fresh'. Issues of oil break down and early rancidity are real, so you have to look at how 'used' is the oil.

While I had no issues due to the oil having been used, I have DOS (rancidity) problems with soy oil. All or most of the 'vegetable oil' used to deep fry are soy oil (in US). Because of soy's high linoleic and linolenic fatty acid content, it is prone to rancidity, short shelf life. To counter that, one can use ROE (rosemary oleo resin). ROE works to some extent, but it becomes one more thing to buy.

If the oils are pretty fresh it can work, but you will have the uncertainty of your soap shelf life. If the oils look dark and have a strong smell, probably best to leave for the biodiesel people.

If someone knows of a method to completely deodorize it I would love to know. Also, somehow removing the oil molecules that have broken down? and without much trouble. Right.

Robert · Sep 19, 2013

Mari33anne said:
Judy "Given that the oil has been subjected to sustained high temperatures, it is likely to oxidize more quickly in soap."

While perusing this forum I sumbled over this " http://www.soapmakingforum.com/showthread.php?t=9163 " and Donniej seems to be hitting the nail on its head, he really is into this thing and I now just hope if he would show up or shime in this discussion or anyone knowing how to get in touch with him.

Darn, such a disappointing ending. Lots of businesses founder on the shoals of partnership, I know from friends. I'd bump the thread, but that doesn't seem much use.

Robert · Sep 19, 2013

neeners said:
there's a company on the island who turns the used cooking oil into bio-diesel, and then hast glycerine leftover at the end. he makes soap with that. not sure what kind of oil he uses (the bf got some bars, but he doesn't know to ask such questions....)

A small amount of soap is also produced as a byproduct of biodiesel (from wet workup/wash of the product), but probably too dilute and lye heavy to be worthwhile recovering.

Robert · Sep 19, 2013

green soap said:
The recycled oils I have used were used to deep fry only once, so they were fairly 'fresh'. Issues of oil break down and early rancidity are real, so you have to look at how 'used' is the oil.

While I had no issues due to the oil having been used, I have DOS (rancidity) problems with soy oil. All or most of the 'vegetable oil' used to deep fry are soy oil (in US). Because of soy's high linoleic and linolenic fatty acid content, it is prone to rancidity, short shelf life. To counter that, one can use ROE (rosemary oleo resin). ROE works to some extent, but it becomes one more thing to buy.

If the oils are pretty fresh it can work, but you will have the uncertainty of your soap shelf life. If the oils look dark and have a strong smell, probably best to leave for the biodiesel people.

If someone knows of a method to completely deodorize it I would love to know. Also, somehow removing the oil molecules that have broken down? and without much trouble. Right.

Maybe activated charcoal. Just a shot.

As to rancid oils, an oxid'n process should exist to convert O-crosslinked oils into hydroxy-oils similar to what's mentioned in the zinc soap deodorant patent I linked to in a recent post. Or find out what breaks down linoleum or varnish!

eyeroll · Sep 22, 2013

Marianne, what was the outcome of this? I've been following this thread and love the idea of recycling oil; I'm curious what you decided to do.

Amy

Sent from my iPhone using Soap Making

Relle · Sep 22, 2013

Marianne, the last time Donnie was in here was January 2012, so probably won't see this.

chemo38 · Jul 10, 2014

The Easy Way.

Forget trying to clean your used cooking oil. Just go on Craigslist and give it to a biodiesel "homebrewer." All homebrewers produce a brown glycerine as a byproduct of making biodiesel. Most don't know what to do with it. Your used frying oil is a commodity to them. Their glycerine is a commodity to you. You can make an excellent liquid or bar soap out of it. I have done it several times. Google "biodiesel glycerine" for reviews. Finally, trade your used oil for brown glycerine. You won't be disappointed.:wave:

Cleaning used cooking oil for soap making

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