Soap is a salt of a fatty acid. It is used for cleaning and lubrication of products. It is a vital ingredient in every household widely used for washing, bathing and other types of housekeeping. It is used in industries as thickener, a component of lubricants and as a catalyst. Chemical formulation of soap reacts with the dirt, grime and oils to take them away from the surface of fabric with running water.

Soap making is a curious activity. Many hobbyists take it as a profession and come forward with new innovative ideas and better techniques of making it. Soap is made by mixing of fats and oils with a base. Different methods are available using which the hobbyists can make soaps.

How is soap made?

Saponification is the activity of making soaps. It comes from the root word “sapo” which literally means “turning into soap”. It is an exothermic chemical reaction in which salt of fatty acids and oils react with lye. It takes about 24 to48 hours. The process can be sped up or slowed by controlling the heat. Saponification can be done using the hot process and cold process, melt and pour process and rebatching process methods. After saponification, a soap needs curing time of four to six weeks i.e. it is left to air dry for this time. It allows excess water to evaporate out of the soap. Then, soaps are stored in different packages keeping in view the fragrance each soap carries.

Both hot process and cold process soap making has three common steps: preparation of lye solution, preparation of oil and mixing both till emulsion takes place.

Hot process method

Most soap making factories use this process. It is simple and easy; so, it’s widely used in small scale factories all over the world. In this process glycerol remains in the product and saponification carries on for many days even after the soap is poured into moulds. The reaction happens in the kettle at high temperature.

Cold Process method

Handmade soaps are generally made using the cold process method. It uses the technique of ‘superfatting’. In this process excess of fat is used and the glycerol that stays in acts as a soap softer and moisturising agent. Glycerine is added to make the soap softer. Superfatted soap is more skin-friendly. The only con is that it leaves the skin a little greasy. For added fragrance, essential oils are added to the soap. For increasing the exfoliation property of soap, sand and pumice are also added. Compounds like triclocarban can be added to give anti-bacterial properties to the soap.

Additives

In hot process, fragrances and essential oils are added to the soap after it is heated.

Fragrances and essential oils are added to the soap in cold process before moulding begins.

Time required

In hot process, the soap is heater using double-boiler technique on low heat 140-176 degrees Fahrenheit. Heat is turned off when soap reaches its gel phase in 1-2 hours. Then, additives like colorants and essential oils are added. The soap is poured into moulds. It is un-moulded after cooling down and left to air dry for a week or two. It is a comparably short process.

In cold process, the soup takes 24-48 hours to set in after it is poured into moulds. As the moulds are insulated, so they act as a heater to make the process speedy. Then soap is un-moulded and left to cure for about 2 weeks before final packaging. This process takes longer than the hot process.

Transparency

Hot process is used to make transparent or liquid soap as the soap passes through its gel phase when it is on heat. This gives amore ‘rustic’ appearance to the soap because of its less smooth texture.

Cold process can’t make fully transparent soap. It is used to make cream soaps and whipped soap that floats on water! It allows the maker to customize every ingredient to suit his/her personal preferences. As the cold process soap is opaque, so glitter does not really work in it. Still, maker can add glitter on top. So, it allows more creativity.

Additives

Hot process uses less additives as the soap-maker has to add them after taking off the soap from heat. But, attention is to be paid that the soap’s temperature does not exceed the flash point of certain additives like essential oils, or they will evaporate.

Cold process uses more additives, but there their essence gets away easily than the soap made with hot process.

Which process to choose?

Hot process and cold process-both have their pros and cons. Cold process takes less time and effort for saponification but takes ages to cure. Sideways, hot process takes time, effort and technical knowledge; but is ready to use once un-molded. One thing is sure, both processes provide equal quench for thirst for curiosity and creativity and give immense satisfaction to the maker.