Soap making is an activity that we can all do in a relatively simple way. We can also control the ingredients we put in the soap and add essential oils or other products that can help our hydration and cleanliness.
Index
WHAT IS SOAP. CHEMICAL FORMULA
The soap is a product used for personal hygiene and for washing certain objects. It is available in tablet, powder, cream or liquid form.
Soaps base their cleaning action on fats with water thanks to the structure of their molecules. Soap has a liposoluble part (dissolves in fats) and a water-soluble part (dissolves in water). This causes the fat-soluble end to carry away fats and the water-soluble end to be carried away by the water.
The reaction by which soap is formed is saponification. It is a sodium or potassium salt from the chemical reaction between an alkali (such as sodium or potassium hydroxide) and a lipid (or fat). The fat used can be of vegetable origin (such as olive oil) or animal origin (such as lard). Soap is soluble in water.
The chemical formula resulting from the saponification reaction is therefore: grease + caustic soda → soap + glycerine.
EXPERIMENTS - HOW TO MAKE SOAP
The traditional method of soap making is through the use of a fat and an alkali. Recently, glycerine bar preparations have also been sold, which are ready-made soaps to which you can add colourings and flavourings.
To make soap with fat and alkali such as sodium hydroxide or caustic soda, when choosing the fat and quantities you have to take into account the saponification index. It is very well explained here: Calculate the quantity of oil and soda.
PRECAUTIONS WHEN MAKING SOAP
If you are going to make soap in the traditional way (with caustic soda or caustic potash and oil) it is very important to be aware of the danger of the elements you are working with.
Caustic soda is highly corrosive, with a pH close to 14 (basic pH and the rightmost on the scale). Sometimes people do not realise that a basic pH (such as caustic soda) is just as corrosive and dangerous as an acidic pH. There have been many accidents where caustic soda has been splashed into the eyes and can cause blindness. It is very important to carry out the process carefully, wearing gloves and goggles. Also, when soda reacts with an acid it causes a very exothermic reaction.
If you have heard that soda is a great plunger (in fact in supermarkets it is sold as a plunger) it is precisely because of its high reactivity and corrosiveness.
Once you have made the soap, it is also important to calculate the amounts of soda and oil. Here is a way to calculate them: Calculate amount of soda and oil. If you add too much soda, it will not react and you will be left with a soap with a very high pH. High pH is corrosive to the skin. Here you can see some pH test strips.