For centuries soap has been made by using what is called the "cold process" method.
This is the simplest way to make soap and involves blending the oil with lye until "tracing" occurs.
At this stage any additives such as scents and nutrient oils are added and the mix is poured into moulds.
The soap is removed from the moulds when hard enough to do so and left to cure in a dark, cool and dry area.
The time taken for mixing and curing varies with the type of oil used, with olive oil being one of the more difficult, taking up to eight weeks to cure.
The advantages of making soap using this method are:
- the glycerin that forms is retained in the soap bar making it moisturising and long lasting;
- no heat is used so the nutrients of the oil are not destroyed;
- no special machinery is required.
The disadvantages are:
- the process is slow;
- labour intensive.