This tip, besides being very practical, also helps us to conserve the environment since cooking oil (olive oil, sunflower oil, etc.) is harmful, and with this kind of ideas, we can give it a more ecological use. What we need for the soap preparation is:

- Vegetable oil (olive oil, for example)
- Caustic soda (we must be careful with caustic soda, as it is corrosive and should not come into contact with skin)
- Gloves to protect hands
- Protective goggles
- Hot water
- A stainless steel container
- A wooden or plastic stick (which we will use to stir the mixture)
- A precision thermometer (it is important that when mixing the oil with the mixture of water and caustic soda, they are at the same temperature)
- Mold

NOTE: The proportions of the mixture that will be useful for making the soap are: 3 liters of oil, 3 liters of water, and half a kilo of caustic soda. Safety Precautions You should take care when using caustic soda as it is highly corrosive and can release toxic gases, so we recommend: - Protect your clothing with an apron. - Use a mask to avoid inhaling toxic gases. - Use goggles to protect your eyes from splashes. - Wear gloves to prevent contact of the soda with the skin (it can cause burns). - If using a blender, keep it submerged. - The pots or containers in which the soap is prepared should be stainless steel (never aluminum, iron, or other materials). Preparation First, you must dissolve the caustic soda in the water, it is very important that it is in this order; otherwise, the chemical reaction it produces can cause serious burns to the skin. Add it slowly and very carefully. This reaction will cause the mixture to heat up to 80°C, wait for it to cool down. What we need to do is pour the oil into the container and then the caustic soda mixture. The mixtures should be approximately at the same temperature (there should be no more than a 5-degree difference). You can heat the oil until it reaches 40°C, which is the ideal temperature. We stir the mixture with the stick, always in the same direction at a moderate speed, until the mixture thickens, and we transfer it to the mold. Let it cool, and that's it. Our soap is ready to use.