Soap is a combination of animal fat or plant oil and caustic soda. When dissolved in water, it breaks dirt away from surfaces. Through the ages soap has been used to cleanse, to cure skin sores, to dye hair, and as a salve or skin ointment. But today we generally use soap as a cleanser or perfume.

The exact origins of soap are unknown, though Roman sources claim it dates back to at least 600 B.C. , when Phoenicians prepared it from goat's tallow and wood ash. Soap was also made by the Celts, ancient inhabitants of Britain. Soap was used widely throughout the Roman empire, primarily as a medicine. Mention of soap as a cleanser does not appear until the second century A.D. By the eighth century, soap was common in France, Italy, and Spain, but it was rarely used in the rest of Europe until as late as the 17th century.

Manufacture of soap began in England around the end of the 12th century. Soap-makers had to pay a heavy tax on all the soap they produced. The tax collector locked the lids on soap boiling pans every night to prevent illegal soap manufacture after hours. Because of the high tax, soap was a luxury item, and it did not come into common use in England until after the tax was repealed in 1853. In the 19th century, soap was affordable and popular throughout Europe.

Early soap manufacturers simply boiled a solution of wood ash and animal fat. A foam substance formed at the top of the pot. When cooled, it hardened into soap. Around 1790, French soapmaker Nicolas Leblanc developed a method of extracting caustic soda (sodium hydroxide) from common table salt (sodium chloride), replacing the wood ash element of soap. The French chemist Eugene-Michel Chevreul put the soap-forming process (called in English saponification) into concrete chemical terms in 1823. In saponification, the animal fat, which is chemically neutral, splits into fatty acids, which react with alkali carbonates to form soap, leaving glycerin as a byproduct. Soap was made with industrial processes by the end of the 19th century, though people in rural areas, such as the pioneers in the western United States, continued to make soap at home.

Raw Materials

Soap requires two major raw materials: fat and alkali. The alkali most commonly used today is sodium hydroxide. Potassium hydroxide can also be used. Potassium-based soap creates a more water-soluble product than sodium-based soap, and so it is called "soft soap." Soft soap, alone or in combination with sodium-based soap, is commonly used in shaving products.

Animal fat in the past was obtained directly from a slaughterhouse. Modern soapmakers use fat that has been processed into fatty acids. This eliminates many impurities, and it produces as a byproduct water instead of glycerin. Many vegetable fats, including olive oil, palm kernel oil, and coconut oil, are also used in soap making.

Additives are used to enhance the color, texture, and scent of soap. Fragrances and perfumes are added to the soap mixture to

The above illustrations show the kettle process of making soap.
The above illustrations show the kettle process of making soap.
cover the odor of dirt and to leave behind a fresh-smelling scent. Abrasives to enhance the texture of soap include talc, silica, and marble pumice (volcanic ash). Soap made without dye is a dull grey or brown color, but modern manufacturers color soap to make it more enticing to the consumer.

The Manufacturing

The kettle method of making soap is still used today by small soap manufacturing companies. This process takes from four to eleven days to complete, and the quality of each batch is inconsistent due to the variety of oils used. Around 1940, engineers and scientists developed a more efficient manufacturing process, called the continuous process. This procedure is employed by large soap manufacturing companies all around the world today. Exactly as the name states, in the continuous process soap is produced continuously, rather than one batch at a time. Technicians have more control of the production in the continuous process, and the steps are much quicker than in the kettle method—it takes only about six hours to complete a batch of soap.

The Kettle Process



Strong change


The Continuous Process



Cooling and finishing



Glycerin is a very useful byproduct of soap manufacture. It is used to make hand lotion, drugs, and nitroglycerin, the main component of explosives such as dynamite.

Where To Learn More


Cavitch, Susan M. The Natural Soap Book: Making Herbal and Vegetable-Based Soaps. Storey Communications, 1995.

Maine, Sandy. The Soap Book: Simple Herbal Recipes. Interweave Press, 1995.

Spitz, Luis, ed. Soap Technologies in the 1990s. American Oil Chemists Society, 1990.


About Soap. Procter & Gamble, 1990. (513) 983-1100.

Sheila Dow

Also read article about Soap from Wikipedia

User Contributions:

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Mar 20, 2008 @ 2:14 pm
I do not know much about making soap, which method you will be using or how much you will make, but I was able to find basic measurements that might help you.

12 oz or 340 grams 100% lye
605 grams ice cold or part frozen distilled water
2.48 kg lard or all vegetable shortening

Good luck, Lacey J.
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Dec 29, 2009 @ 12:00 am
Nice article.Kindly let me know how much quantities of raw material to take to make soap at home.
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May 30, 2010 @ 10:22 pm
good one but i think chemical reactions should be given to make it more like chemistry.
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Jun 22, 2011 @ 1:01 am
Nice information i want to know that soapstone powder is also used in soap manufacturing process
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Aug 19, 2011 @ 5:05 am
my soap get shrinking after some day of production using cold process please help me Can i use beeswax as incredient in my in my formulation?
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Mar 25, 2012 @ 9:21 pm
nice artile. BUT some info missing.indly let me know how much quantities of raw material to take to make soap at home.
haji m amin
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Aug 14, 2014 @ 10:10 am
I like to know how to laundry bar soap these days commercial way for the market
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Aug 20, 2014 @ 2:02 am
I saw that in a factory line soap they use soap noodles (chips), a kind of color ,a kind of fragrance and some chemical ingredients. What are those ingredients and how to know amount (measure)?Thx
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Apr 19, 2015 @ 2:02 am
1 The first step of the continuous process splits natural fat into fatty acids and glycerin. The equipment used is a vertical stainless steel column with the diameter of a barrel called a hydrolizer. It may be as tall as 80 feet (24 m). Pumps and meters attached to the column allow precise measurements and control of the process. Molten fat is pumped into one end of the column, while at the other end water at high temperature (266°F [130°C]) and pressure is introduced. This splits the fat into its two components. The fatty acid and glycerin are pumped out continuously as more fat and water enter. The fatty acids are then distilled for purification.
Sam Abbey
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Sep 18, 2017 @ 7:07 am
Please send to me the measurements in kg conversion. Also, can one mix soda ash, caustic soda and water with preferred fragrance to make a locally used soap? Thanks.
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Sep 18, 2017 @ 7:19 pm
Caustic soda, Soda ash, palm kernel oil, silicate, fragrance, this are the ingredients i use in making my own soap but after a while i find out that the soap shrinks, pls i need help on how to make it not to skrink anymore.

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