Dishwashing Soap made from Used Cooking Oil - Japan - ARI
by the Asian Rural Institute
page developed by Marie Kessler, ARI Volunteer
submitted August 2023
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It is the soap that we use to wash dishes at ARI!
Can we make soap from used cooking oil? YES!
Everyone who has been to ARI has spent time soaping up the plates, cups, and silverware to make them squeaky clean! We all know how important this is for our health and hygiene. I actually like washing the dishes, making sure they are sterile and safe for our community. I also love dishwashing time, talking and SINGING with my fellow dishwashers. But did you know that we make our own dishwashing soap? All we need is water, oil, and caustic soda!
Why do we make soap in ARI?
Making our own soap, allows us to turn a waste into a resource. Instead of throwing away our old cooking oil we can make soap! This is good for the environment and we can save money. Furthermore we can teach others how to make their own soap! This is one more way we can live sustainably at ARI!
ARI Oil
ARI cooking oil is soybean oil. We use it to make Samosas, Nigerian Eggrolls, Tempura and many other delicious things in the kitchen. When the oil gets old after many uses, we can use it to make soap! For making soap, any kind of cooking oil can be used.
How we make soap at ARI
Three phases:
Phase 1 - Preparation
Phase 2 - Process of making the soap
Phase 3 - Resting the soap
Phase 1 - Preparation
What materials do we need?
Caustic Soda - the chemical that combines the water and oil
Water - we use our own ARI water
Used cooking oil - it must be an oil used for cooking food; any old kitchen oil is okay
Mold (container for the soap) - these can be any type of container, like a tofu or yogurt box, or a styrofoam box
Strainer - to strain the oil before mixing it with the other ingredients
Thermometer - to check the temperature of the oil
A long wooden stick - to stir the ingredients
Large container - a large container for mixing the ingredients; it should be stainless steal, glass, pottery or enamel.
DO NOT use Aluminum or Iron! The caustic soda will fuse with the container. It is very DANGEROUS and will damage anything in the area!
Protective clothing - rubber gloves, goggles (to cover your eyes), mask
Caustic soda is a strong and dangerous chemical. You must wear rubber gloves. Goggles (eye protection) and a mask are recommended.
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Caustic soda and rubber gloves - you must wear gloves when handling caustic soda
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Large containers for mixing the ingredients, and long sticks for stirring
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Measuring cup, strainer and thermometer
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Molds (containers for the soap) that we use at ARI. These have a wide top, so it is easy to use the soap inside.
Setting up the working space
During the soap making process make sure no children are around!
Work in an area with good air ventilation and no strong wind.
Get all the ingredients and materials ready to use on the spot!
Phase 2 - The process of making soap
1 - Strain the waste oil with the strainer to remove in particles
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Straining the oil
2 - measure out the needed amounts of water, oil, and caustic soda.
Ratio used at ARI: Caustic Soda (one can) 450g / water 1 liter / oil 2.8 liters
3 - Warm up the oil to about 40℃. In ARI we use the gas stove in the kitchen.
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Warming up the oil; controlling the temperature with a thermometer
Safety note: Wear gloves and a mask when handling caustic soda. Never touch caustic soda with bare hands! If your skin gets exposed to the caustic soda, rinse immediately under running water!
4 - Add the caustic soda to the water. Stir it well with the long wooden stick.
Safety note: Never put the water onto the caustic soda! You cannot control the reaction or amount.
Safety note: During the mixing process fumes will come out. They might hurt your eyes or lungs. Use a mask to cover your face to avoid any bad fumes.
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Mixing caustic soda with water, wearing rubber gloves
5 - When the caustic soda is completely dissolved in the water and the liquid becomes transparent, pour the warm oil into it.
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Pouring the warm oil into the caustic soda and water mixture
6 - Stir the mixture for 30-40 minutes. When the mixture becomes whitish and gains texture (viscosity), you can stop stirring.
7 - The last step is to pour the mixture into the molds (containers).
If you do not have any molds, you can pour the mixture into a baking tray and cut it after the resting time.
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Pouring the mixture into the molds (containers)
Phase 3 - Resting the soap
The soap must be rested for at least 1 month. It will become hard in about one week. But you need to wait three more weeks before it is ready to be used. The soap is harmful and irritating to your skin if you use it before one month has passed.
Do not use it sooner than the one month!
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ARI "rests" the soap in styrofoam boxes. The date, type of oil, and group members who made it are written on the boxes.
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Finished soap
That is all there is to it!
Try making your own soap with used cooking oil and share your results with us (gradout@ari-edu.org).
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