If the idea of making soap from oil seems far to you, let’s examine the formula of the soap. Soap; Chemically, it is formed as a result of the interaction of fatty acids with a basic substance. The resulting substance clings to oil-based dirt with the oil-containing part and water with the base-containing part, removing the dirt from the surface. Soaps are often named for the ingredient that is the source of these fatty acids, and this ingredient can range from coconut oil to olive oil. Since the waste oil you use while frying is actually one of the oils such as sunflower, cotton or olive oil, there is no reason not to use these waste oils in soap making.
The formation process of soap
The process known as saponification begins when any animal or vegetable fatty acid interacts with NaOH, a basic substance known as caustic. When this reaction is completed, the used oil and base lose their chemical properties and form the substance we call soap and gain new chemical properties.
- 1 liter of waste oil
- 1 liter are
- 160 grams of caustic
- protective clothing
- A glass or plastic container and mixing tool
- Fragrant essential oils of your choice
1- Before starting the classical saponification stages, filter the food pieces that may have been mixed with the oil during frying by passing the oil through a fine cheesecloth.
2- Be sure to wear protective gloves, goggles and a mask, apron.
3- Put a liter of water in the container you will use.
4- Add caustic to the water and mix it slowly. With the reaction occurring at this stage, the temperature of the mixture can reach 80 degrees and the resulting gas is a dangerous, poisonous gas to breathe. If possible, do this outside in front of a window or ventilation, if not outside, and try not to breathe.
5- Leave the mixture to cool until it approaches room temperature. If you want to add it, you can add essential oils at this stage.
6- Slowly pour the waste oil into the mixture that comes to the appropriate temperature and mix. Stir with a spoon for about half an hour, being careful not to cut it in the same direction.
7- When the mixture reaches the consistency of a thick paste, pour it into suitable containers to take shape and let it dry for 30 days.
- Make sure that the materials you use are not metals, as they may react chemically.
- Avoid contact with food, as the container and mixing tools you use may contain caustic residues.
- Do not use before 30 days in order to complete the saponification reaction and not have an irritating effect.
- If you do the process indoors, make sure to ventilate the area afterwards.
- You can prepare a mold for soap by cutting one side of an empty milk or juice can, and after a few days after pouring the soap, you can cut it into pieces with a knife.
- The oil and caustic ratio is different for each oil type. This is called the saponification coefficient of the oil. You can do a more professional job by using this coefficient according to the type of oil you use.
Zoë Lenkiewicz. “How to make soap using waste oil”. Şuradan alındı: https://wasteaid.org/how-to-make-soap-using-waste-oil/ (31.04.2020).