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The History of Soap

How soap works

Soaps are useful for cleaning because soap molecules attach readily to both nonpolar molecules (such as grease or oil) and polar molecules (such as water). Although grease will normally adhere to skin or clothing, the soap molecules can attach to it as a "handle" and make it easier to rinse away. Applied to a soiled surface, soapy water effectively holds particles in suspension so the whole of it can be rinsed off with clean water.

(fatty end) :CH3-(CH2)n - COONa: (water soluble end)

The hydrocarbon ("fatty") portion dissolves dirt and oils, while the ionic end makes it soluble in water. Therefore, it allows water to remove normally-insoluble matter by emulsification.


The most popular soapmaking process today is the cold process method, where fats such as olive oil react with lye. Soapmakers sometimes use the melt and pour process, where a premade soap base is melted and poured in individual molds. While some people think that this is not really soap-making, the Hand Crafted Soap Makers Guild does recognize this as a legitimate form of soap making or soap crafting. Some soapers also practice other processes, such as the historical hot process, and make special soaps such as clear soap (glycerin soap), which must be made through the melt and pour process.

Handmade soap differs from industrial soap in that, usually, an excess of fat is sometimes used to consume the alkali (superfatting), and in that the glycerin is not removed leaving a naturally moisturising soap and not pure detergent. Superfatted soap, soap which contains excess fat, is more skin-friendly than industrial soap; though, if not properly formulated, it can leave users with a "greasy" feel to their skin. Often, emollients such as jojoba oil or shea butter are added 'at trace' (the point at which the saponification process is sufficiently advanced that the soap has begun to thicken), after most of the oils have saponified, so that they remain unreacted in the finished soap. Superfatting can also be accomplished through a process called superfat discount, where, instead of putting in extra fats, the soap maker puts in less lye.


Reacting fat with sodium hydroxide will produce a hard soap

Reacting fat with potassium hydroxide will produce a soap that is either soft or liquid. Historically, the alkali used was potassium hydroxide made from the deliberate burning of vegetation such as bracken, or from wood ashes.


Soap is derived from either vegetable or animal fats. Sodium tallowate, a common ingredient in many soaps, is in fat derived from rendered beef fat. Soap can also be made of vegetable oils, such as palm oil, and the product is typically softer. If soap is made from pure olive oil it may be called Castile soap or Marseille soap. Castile is also sometimes applied to soaps with a mix of oils, but a high percentage of olive oil.

An array of oils and butters are used in the process such as olive, coconut, palm, cocoa butter, hemp oil and shea butter to provide different qualities. For example, olive oil provides mildness in soap; coconut oil provides lots of lather; while coconut and palm oils provide hardness. Most common, though, is a combination of coconut, palm, and olive oils.


In both cold-process and hot-process soapmaking, heat may be required for saponification.

Cold-process soapmaking takes place at a temperature sufficiently above room temperature to ensure the liquification of the fat being used, and requires that the lye and fat be kept warm after mixing to ensure that the soap is completely saponified.

Unlike cold-processed soap, hot-processed soap can be used right away because lye and fat saponify more quickly at the higher temperatures used in hot-process soapmaking.

Hot-process was used when the purity of lye was unreliable, and can use natural lye solutions such as potash. The main benefit of hot processing is that the exact concentration of the lye solution does not need to be known to perform the process with adequate success.

Cold-process requires exact measurement of lye to fat using saponification charts to ensure that the finished product is mild and skin-friendly. Saponification charts can also be used in hot-process soapmaking, but are not as necessary as in cold-process.

Hot Process

In the hot-process method, lye and fat are boiled together at 80–100 °C until saponification occurs, which the soapmaker can determine by taste (the bright, distinctive taste of lye disappears once all the lye is saponified) or by eye (the experienced eye can tell when gel stage and full saponification have occurred).

After saponification has occurred, the soap is sometimes precipitated from the solution by adding salt, and the excess liquid drained off.

The hot, soft soap is then spooned into a mold.

Cold Process

A cold-process soapmaker first looks up the saponification value of the fats being used on a saponification chart, which is then used to calculate the appropriate amount of lye. Excess unreacted lye in the soap will result in a very high pH and can burn or irritate skin. Not enough lye, and the soap is greasy. Most soap makers formulate their recipes with a 4-10% discount of lye so that all of the lye is reacted and that excess fat is left for skin conditioning benefits.

The lye is dissolved in water. Then oils are heated, or melted if they are solid at room temperature. Once both substances have cooled to approximately 100-110° F, and are no more than 10° F apart, they may be combined. This lye-fat mixture is stirred until "trace" (modern-day amateur soapmakers often use a stick blender to speed this process). There are varying levels of trace. Depending on how your additives will affect trace, they may be added at light trace, medium trace or heavy trace. After much stirring, the mixture turns to the consistency of a thin pudding.

Essential oils, fragrance oils, botanicals, herbs, oatmeal or other additives are added at light trace, just as the mixture starts to thicken.

The batch is then poured into molds, kept warm with towels or blankets, and left to continue saponification for 18 to 48 hours. Milk soaps are the exception. They do not require insulation. Insulation may cause the milk to burn. During this time, it is normal for the soap to go through a "gel phase" where the opaque soap will turn somewhat transparent for several hours before turning opaque again. The soap will continue to give off heat for many hours after trace.

After the insulation period the soap is firm enough to be removed from the mold and cut into bars. At this time, it is safe to use the soap since saponification is complete. However, cold-process soaps are typically cured and hardened on a drying rack for 2-6 weeks (depending on initial water content) before use. If using caustic soda it is recommended that the soap is left to cure for at least 4 weeks.

Purification and finishing

The common process of purifying soap involves removal of sodium chloride, sodium hydroxide, and glycerol. These components are removed by boiling the crude soap curds in water and re-precipitating the soap with salt.

Most of the water is then removed from the soap. This was traditionally done on a chill roll which produced the soap flakes commonly used in the 1940s and 1950s. This process was superseded by spray dryers and then by vacuum dryers.

The dry soap (approximately 6-12% moisture) is then compacted into small pellets. These pellets are now ready for soap finishing, the process of converting raw soap pellets into a salable product, usually bars.

Soap pellets are combined with fragrances and other materials and blended to homogeneity in an amalgamator (mixer). The mass is then discharged from the mixer into a refiner which, by means of an auger, forces the soap through a fine wire screen. From the refiner the soap passes over a roller mill (French milling or hard milling) in a manner similar to calendering paper or plastic or to making chocolate liquor. The soap is then passed through one or more additional refiners to further plasticize the soap mass. Immediately before extrusion it passes through a vacuum chamber to remove any entrapped air. It is then extruded into a long log or blank, cut to convenient lengths, passed through a metal detector and then stamped into shape in refrigerated tools. The pressed bars are packaged in many ways.

Sand or pumice may be added to produce a scouring soap. This process is most common in creating soaps used for human hygiene. The scouring agents serve to remove dead skin cells from the surface being cleaned. This process is called exfoliation. Many newer materials are used for exfoliating soaps which are effective but do not have the sharp edges and poor size distribution of pumice.

Early history

The earliest known use of a natural soap-like substance was the powder of the Reeta (Sapindus) nut, which was used by Indians since antiquity. Hindus in India were obliged to bathe at least once a day, every morning, in accordance with Ayurveda. Evidence of manufactured soap use are Babylonian clay cylinders dating from 2800 BC containing a soap-like substance. A formula for soap consisting of water, alkali and cassia oil was written on a Babylonian clay tablet around 2200 BC.

The Ebers papyrus (Egypt, 1550 BC) indicates that ancient Egyptians bathed regularly and combined animal and vegetable oils with alkaline salts to create a soap-like substance. Egyptian documents mention that a soap-like substance was used in the preparation of wool for weaving.

Roman History

It had been reported that a factory producing soap-like substances was found in the ruins of Pompeii (79 AD). However, this has proven to be a misinterpretation of the survival of some soapy mineral substance,[citation needed] probably soapstone at the Fullonica where it was used for dressing recently cleansed textiles. Unfortunately this error has been repeated widely and can be found in otherwise reputable texts on soap history. The ancient Romans were generally ignorant of soap's detergent properties, and made use of the strigil to scrape dirt and sweat from the body. The word "soap" (Latin sapo) appears first in a European language in Pliny the Elder's Historia Naturalis, which discusses the manufacture of soap from tallow and ashes, but the only use he mentions for it is as a pomade for hair; he mentions rather disapprovingly that among the Gauls and Germans men are likelier to use it than women.

A story encountered in some places claims that soap takes its name from a supposed "Mount Sapo" where ancient Romans sacrificed animals. Rain would send a mix of animal tallow and wood ash down the mountain and into the clay soil on the banks of the Tiber. Eventually, women noticed that it was easier to clean clothes with this "soap". The location of Mount Sapo is unknown, as is the source of the "ancient Roman legend" to which this tale is typically credited. In fact, the Latin word sapo simply means "soap"; it was borrowed from a Celtic or Germanic language, and is cognate with Latin sebum, "tallow", which appears in Pliny the Elder's account. Roman animal sacrifices usually burned only the bones and inedible entrails of the sacrificed animals; edible meat and fat from the sacrifices were taken by the humans rather than the gods. Animal sacrifices in the ancient world would not have included enough fat to make much soap. The legend about Mount Sapo is probably apocryphal.

Muslim history

True soaps made from vegetable oils (such as olive oil), aromatic oils (such as thyme oil) and Lye (al-Soda al-Kawia) were first produced by Muslim chemists in the medieval Islamic world. The formula for soap used since then hasn't changed. From the beginning of the 7th century, soap was produced in Nablus (West Bank, Palestine), Kufa (Iraq) and Basra (Iraq). Soaps, as we know them today, are descendants of historical Arabian Soaps. Arabian Soap was perfumed and colored, some of the soaps were liquid and others were hard. They also had special soap for shaving. It was sold for 3 Dirhams (0.3 Dinars) a piece in 981 AD. The Persian chemist Al-Razi wrote a manuscript on recipes for true soap. A recently discovered manuscript from the 13th century details more recipes for soap making; e.g. take some sesame oil, a sprinkle of potash, alkali and some lime, mix them all together and boil. When cooked, they are poured into molds and left to set, leaving hard soap.

In semi-modern times soap was made by mixing animal fats with lye. Because of the caustic lye, this was a dangerous procedure (perhaps more dangerous than any present-day home activities) which could result in serious chemical burns or even blindness. Before commercially-produced lye (sodium hydroxide) was commonplace, potash, potassium hydroxide, was produced at home for soap making from the ashes of a hardwood fire.

Modern History

Castile soap was later produced in Europe from the 16th century.

In modern times, the use of soap has become universal in industrialized nations due to a better understanding of the role of hygiene in reducing the population size of pathogenic microorganisms. Manufactured bar soaps first became available in the late nineteenth century, and advertising campaigns in Europe and the United States helped to increase popular awareness of the relationship between cleanliness and health.

Rarely, conditions allow for corpses to naturally turn in to a soap-like substance, such as the Soap Lady on exhibit in the Mutter Museum.

Commercial soap production

Until the Industrial Revolution soap-making was done on a small scale and the product was rough. Andrew Pears started making a high-quality, transparent soap in 1789 in London. With his grandson, Francis Pears, they opened a factory in Isleworth in 1862. William Gossage produced low-price good quality soap from the 1850s. Robert Spear Hudson began manufacturing a soap powder in 1837, initially by grinding the soap with a mortar and pestle. William Hesketh Lever and his brother James bought a small soap works in Warrington in 1885 and founded what is still one of the largest soap businesses, now called Unilever. These soap businesses were among the first to employ large scale advertising campaigns.

Source: Wikipedia

Soap use in therapy

Previously, soap was regarded as an “exterior healer,” but in time, it began to be used for body hygiene. Up to today, soap is used as a disinfectant against contagious diseases. The Egyptians, who cared a lot about their personal hygiene, used to bathe with a soap-like material that was made from animal and vegetable oils mixed with alkali salt. In this way, they achieved personal hygiene and they also healed their wounds. Galenos Klaudios, an ancient Greek doctor who lived in the 2nd century A.D., claimed that soap was effective against skin diseases and recommended soap to his patients. Moses, who was a leader in hygiene, cared as much about hygiene criteria as religious rules, and asked for the Israeli people to keep their garments clean as a symbol of their religious purification. Moses was aware that filth had reached harmful limits and had started to threaten his people. For him, a lack of hygiene was “deadly”, it meant disease. In those times, leprosy and filth were regarded as synonyms. Today, various soaps are used in therapy: Almond oil soap: It is made from almond oil and sodium hydroxide, and is used as a liquid oil in various drugs. Tallow soap is made from animal oils and sodium hydroxide; its solution with alcohol is a gel that forms the main element of opedeldoc balsam. Yellow soap; potash soap or soft soap, is sometimes used in treating scabies. Coconut oil soap with potash is dissolved in water appropriately and sterilized to produce surgical soap. (it is used to sterilize hands and gloves before surgery). Solid soaps with various drug additives (sulphur, ihtiyol, tar, and various antiseptics) make up the surgical soap group and are used in dermatosis.

Soap and The Ottomans

Turks used substances in water like soda, polo mallet, smilax, bouncing bet, süt kökü, agrimony, kılaya kavuğu, quassia, evergreen cyclamen and horse chestnut instead of soap until approximately the 11th century. Documents show that soap as it is today was first made by Arabs in ancient times. Soap production was a developed industry among Islamic countries in the Middle Ages. During the Ottoman Empire, soap craftsmen attended trade fairs in organized ceremonies. We see from archive evidence that soap manufacturing and consumption was highly prevalent with the Ottomans.

The Ottoman Empire was very substantial in terms of soap production. Tripoli soap, flower soap, musk soap, Hünkari soap, white and black pasha soap, variegated soap, black soap, scented soap, Kandiye soap, Cretan soap, soft soap, stain soap and fez soap... These are just a few of the types of soaps produced within the empire... With the Ottomans, the first regulations regarding soap are seen in the statute books of Fatih Sultan Mehmet, Beyazıt the 2nd, Yavuz Sultan Selim and Kanuni Sultan Süleyman’s periods. Legal regulations can be found on the topic of Foça soapery during Fatih’s period, and in the Tripoli Sanjak code during Yavuz’s period. In the subsequent periods, the abundance of documents and regulations regarding soap production, quality, price, control, trade and soap craftsmen is remarkable. Soap is basically produced from the reaction of sodium salts with fatty acids obtained from substances like olive oil, olive-pomace oil, sunflower oil, peanut oil, palm oil, and suet. Soap production consists of four stages: washing, firing, liquidizing and saponification. During kneading, perfumes are added to achieve scented soaps.

In the Ottoman Empire, soap was manufactured in private production facilities called ‘soaperies’ with conventional methods. The raw material of soap was olive oil and suet. The soaps which had economic value and which were preferred were those produced from olive oil. In the Ottoman Empire, soap production was mostly done in East Anatolia and the Islands, Damascus, Aleppo and Namlus, where olive oil was plentiful. In that period, soap was mostly produced in Mytilene and Crete Islands, Ayvalık, Edremit, Kemer Edremit, İzmir, Kızılcatuzla, Yunda Island and Urla. Most of the soap produced in these centers was spared under the name of ‘Dersaadet allocation’ in order to meet the needs of the palace, the army and Istanbul’s people. The highest quality and most preferred soaps of the Ottoman Empire were produced on Crete Island, and especially in Kandiye. Kandiye soaps were well-known for being clean and fired well. Due to these properties, Cretan soaps were copied; soaps from Mytilene and Edremit were stamped as ‘Cretan Soap’ and this led to the rise of complaints from Cretan soap producers. Mainly from Hanya, Kandiye, and Resmo, the olive oil obtained from Crete was mostly used in soap production. In the early 18th century, the number of soaperies was only a few in Crete, but this increased more than ten times in the middle of the century and reached 45. Tripoli, in Lebanon, was also a city where olive oil was plentiful and soap production was accordingly higher. Especially in Nablus, Jerusalem, Rakka and Damascus, the soap industry was highly developed and these cities exported soap. Here, the history of soap went all the way back to the middle of the 14th century. The soap needs of Anatolia and Egypt were mainly supplied from these regions. Twelve soaperies were established in Halep, which was famous for its soap and had exported soap. Besides meeting the local demand, soaps produced in Halep and its surroundings were also exported outside of Syria by European trade companies and large traders. ‘Musk soap' produced in Edirne and Jerusalem was among the valuable gifts given to the Ottoman palace, sultans and high government officials.

Fruit Soaps

When we consider the recent entrance of perfumed soaps into our lives, the fact that the use of fruit soaps in our country dates back to three hundred years ago brings a historical significance to soaps. What looked like plastic fruits at first glance could only be distinguished by the eyes of those who were familiar, and these fruit soaps were used both for hygiene and as ornaments throughout history. Fruit soaps were the most important trade item in the 19th century and they were produced in the shapes of apples, pears, grapes, peaches, cherries, bananas, melons, strawberries, apricots and lemons, and each had their own original scent. When we consider that oil from plants and herbs is absorbed directly into the body through the nose, lungs and skin, we see that these soaps go beyond being just ornaments, and act as a natural remedy. We can also say that fruit essence soaps formed the basis of today’s lemon, peach and apple scented soaps and shampoos. Fruit soaps used previously for cleaning purposes and are used only for decoration today are produced by melting common green soaps. After adding a few drops of rose oil, the liquidized soap is allowed to cool. The next stage is kneading the soap dough. The dough is given the shape of the fruit which gave the soap its scent. Finally, it is painted in the fruit's colors and is ready. Not all of the soaps produced were sold commercially, most of them were sent to Topkapı Palace in İstanbul as per the sultan’s wish. The nice smelling fruit soaps were also very valuable ornaments. Especially princesses and women of the harem placed these soaps in their rooms. Care was also taken to include fruit soaps among the presents that were sent by sultans for foreign heads of states.

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