You will need:
- 1 litre of oil used for frying
- 1 litre of water (rainwater works best)
- 160g of 90% caustic soda (buy at a pharmacy)
- 20-40ml of essential oil (optional)
- Goggles, if in an enclosed place
- Utensils to stir the mixture
- Container to mix ingredients
Before you begin, you have to put on gloves because caustic soda can cause skin damage and if you are in an enclosed space, it is recommended that you wear goggles so that the vapours do not irritate your eyes.
Steps to make soap
1. Put the water into a large plastic or stainless steel container.
2. Add the caustic soda and stir until it dissolves in the water. Be very careful because the temperature will increase to around 80ºC and generate vapours which should not be inhaled as they are toxic.
3. Leave to stand and cool to about 35°C. If you want to add some essential oils, do so now.
4. Slowly pour the cooking oil onto the water and soda and stir the mixture constantly always in the same direction (so they do not cut), for about 30 to 40 minutes, until the mixture begins to thicken during the saponification process.
5. When the mixture has a paste-like texture, pour it into the moulds.
6. Leave the soap to dry for about 30 days.
You can find caustic soda in pharmacies. You must keep it out of reach of children, as it is a dangerous product.
It is recommended that you make the soap in an open or very well-ventilated area, wear long-sleeved shirt and long trousers to protect yourself from possible splashes or even where a plastic apron.
If you want to cut the soap into bars, you can do it with a knife the day after making the mixture, when it has acquired some consistency.
It is very important that you do not use soap during the 30 days of its development, as it may contain trace amounts of soda and irritate the skin.
Use extreme precaution when handling caustic soda.