Soap With Used Cooking Oil





Introduction: Soap With Used Cooking Oil

Easy and cheap way of making soap.
Avoid the obstruction of kitchen pipes and the polution made by the used cooking oil!

Step 1: Materials

You will need this materials to make a good home made soap.

Step 2: Soap Recipe and Fabrication

First I will give you the base recipe for one liter of used cooking oil.

1 liter of used cooking oil
200 grammes of caustic soda (NaOH)
400 milliliters of warm water
40 milliliters of softener for clothes

1. mesure the cooking oil and put on a recipient after filtering impurities out
2. mesure the water
3. weight the caustic soda
4. dissolve the caustic soda with the water (use mask, glasses and protection gloves because the mixture will boil and release toxic gases)
5. join the mixture with the oil
6. stir 15 minutes with a wooden spoon, until the prepared becomes consistent and put the softener for clothes to give the soap softness and fragrance

Step 3: Final Preparations

Put the soap in diferent recipient and let it dry two days. You will see when you can take it out of the containers when we turns white.

Let it curate two weeks, the soap will turn much more soften.



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Does this soap ever come "trace" stage? I've tried 3 batch's and it never seems to be right. I've measured everything very carefully and it just doesn't come out right.

2 replies

Did you use pure NaOH? A lot of houshold products contains much sodium carbonate and that won't work...

Yes is was pure NaOH. I make a fair amount of lye and pine tar soap. Never a problem with those. This just does not work out for me.

Hate to say it, but doesn't laundry softener contain ground up glass? Or am I getting it mixed up with laundry detergent? Either way, I would hate to be eating or washing with glass!!!!

2 replies

Laundry soap and detergent do not contain glass. That would be illegal and be a massive recall.

doxielover4ever, kindly please let me know where you heard that laundry softener or detergent contains ground up glass? That is the biggest load of nonsense.

The ONLY use for ground up glass in any cleaning product would be in a metal polish, and even then silica is used, not glass as such.

The only thing used in SOME laundry detergents is Sodium Metasilicate Pentahydrate, otherwise known as Liquid Glass or Waterglass.

So no, it doesn't contain ground up glass, and I'm in the chemical manufacturing industry.

My soap is curing , I tried a bit but it was very burning ,is that because the soap didnt stand for 2 weeks , and das it loose is that sting later?

2 replies

Soap needs to cure for 4-6 weeks. Some up to 8 depending on water content and how muxh soft oils used.

Hi Susanna. Maybe a bit late of a reply, but perhaps others like to know too. If the soap burns that means the pH is too high still. Either you have added too much caustic soda, or the reaction between the caustic soda and the oil isnt finished yet. I think it is probably the latter, as I normally take a month to cure my soap, so 2 weeks might be a bit short.

Many thanks for the recipe--my first experience with soap making. A number of things went wrong during the procedure and the mixture solidified into a very hot orange, flaking, putty that had to be pressed into the mold rather than poured, possibly due to too much caustic soda . In any case had fun and vow the next batch will be better.

Can't understand half these instructions. The English is not correct.

I just tried making my first batch ... Let's see how it turns out ...

Just one possible problem -- when I poured my batch to set in the mold, it still seemed alittle something between watery and oily in some places (especially corners) ... Is this to be expected and will it dry away ??? If it isn't the desired result, should I have used alittle more lye or alittle less water and oil ???

Sure would appreciate input !!!

Very nice video and great recipe i use it myself, just make adjustments for adding some Borax for extra suds or any frangrances and colors.

Any kind of soap that you have made or make using Lye needs to cured for at least 6 weeks or it will burn your skin. 6 to 8 weeks is best. Lye soap is still the best soap to use for general cleaning hands or body, but i wouldnt use it on your hair its a bit harsh to the hair.

Hi there!

I just made the soap form the oils ,Well I love it ,made 2 batch one with lavender and one with lemongrass fragrance ,still warm ,so I cant use it just jet ,but I be making one lot every day ,I got at least 10 litters of fresh oil . thank you for posting

Would the soap be better suited to use on the body if there were no fabric softener?

For filtering waste grease: if your grease is not fully liquid warm it just until it is. We don't need any grease burns here! Pour the grease through a seive lined with a filter of some sort. Coffee filters, paper towels and scraps of fabric work. I saw a demonstration of old fashioned soap making using unfiltered soap. The daughter said they would find bits of crispy pork fat in their bath soap.

Thankyou for the recipe for used cooking oil.

One caution: lye (caustic soda) should never be put in hot water. Use very cold water instead of warm. It will still get very hot as the water and lye react.


I have been using WVO for years in my car and have recently tried making soap with it. It worked out great. I just used the cold process with a basic recipe with a bout 25% coconut oil (76 deg). I tested and started using it within three days and it has great cleaning power and is not harsh. Can't wait to see what it is like after some curing time. It had no "used cooking oil smell" after it was processed.
I have a question I can't find an answer for by other internet searches:
Since I collect oil from several restaurants the oil is not consistent. How would I do a titration on it to find out how much lye to use All the soap calculators assume you know the type of oil you are using.

Thanks Gang



...NOW...if someone could just do an Instructable on "How to make a Soap Mold/Press" ..we'd be in Heaven !!!!!!!

To recycle the cooking/frying oils into household cleaning soaps is the long exist process in Asian countries for many generations. This is an ecological method of reducing environment pollution and was published by United Nation Civil Society of Brazilian Foundation of America.


Since the oil has been break down due to the extended high temperature cycles, the trace of cold process soapmaking starts immediate after the oil combines with lye water. You can use the lemongrass or lavender infused water in this process to eliminate the light oily smell. The soap will be ready after 3 weeks of curing. The PH should be at 8 or less. It is safe for your skin.

We have produced the eco-friendly soap with the oils that we collected from neighbourhood restaurants for charity fund raising. The cleaning power is extremely strong. On top of that, this soap is enriched with natural glycerin that was produced by the natural saponification process. It helps your skin to retain moisture after you use it. Your skin won't feel dry or cracked.

Due to the nature of the oil, this soap is not recommended to use on your body or on your pet. You can use it to clean your dishes, oven, stoves, laundry, floors and any other household cleaning. You also can make liquid soap with it by thread the soap then add one part of hot lavender infused water and 2 part of hot water. Stir gently, let stand 30 minutes then stir again. Let stand overnight then gently stir again. It can replace your hand liquid soap, kitchen dish detergent and laundry detergent.