Soap was used for centuries before manufacturers invented shower gel. Because it was retro - and a bit too harsh - it was then forgotten. And now it's making a comeback thanks to the Solid Cosmetics & Zero Waste trends. Is this a reason to go all out for soap?
A bit of history
The first chemical reaction invented by man
The Egyptians already washed with a form of soap composed of animal fat and vegetable oils mixed with trôna, a mineral similar to soda. In Gaul, we find traces of a mixture of goat tallow, lard and cooking oils, mixed with ashes. These are what are called "soft soaps", without cooking.
It was in Aleppo (in present-day Syria) that craftsmen invented, a millennium BC, the first hard soap and its manufacturing principle, saponification, which is the oldest chemical reaction invented by man. The principle is described in the most famous treatise on Arabic medicine of the Middle Ages, the Kitab al-Mansouri fi al-Tib: a mixture of olive oil, vegetable soda, laurel ash and water that boils in copper cauldrons. The blocks of soap are then dried for 12 months in the sun. This recipe, which is said to have reached Europe during the Crusades, is the ancestor of all hard soaps.
Aleppo, Castile and Marseille


Two other soaps owe their reputation to the exchanges and upheavals of the Middle Ages: Castile soap and Marseille soap. While the former is made cold and contains only olive oil, the so-called Marseille soap is made hot, with excess soda then rinsed off. Because, contrary to popular belief, the Middle Ages were a period conducive to hygiene and body care. The Edict of Colbert in 1688 regulated the manufacture of Marseille soap: based on pure olive oil from Provence, salt and soda directly transported from Camargue, but the use of tallow (animal fat) was strictly prohibited.
With the first colonies, and the scarcity of olive oil, soap factories turned to other oils, notably palm and coconut, which produced a white or beige Marseille soap that could be used to wash delicate fabrics. In 1906, the term "Extra pure 72% oils" was defined in contrast to soaps that were beginning to be industrialized and which could contain up to 50% water. Because, from the 19th century, soap production became excessively industrialized and made it an ordinary product. Made with low-end oils, from which the glycerin was separated to sell to other industries, it contained more and more water so that it dried out the skin. Until the shortage of fatty substances at the end of the Second World War and the rise of chemistry led to the appearance of synthetic surfactants, the origin of syndets and shower gels. These products, which are less expensive to produce, are enjoying great success. Ironically, these synthetic surfactants are softened with glycerin sold by the soap industry!
Why does soap wash?
Composed of natural ingredients - vegetable oils (olive oil, palm oil, coconut oil , etc.) to which a mineral base is added (soda for a hard soap, potash for a soft or liquid soap) and possibly additions such as honey, milk, essential oils - soap has the power to fix fats in the rinsing water and therefore to wash! This is also why we say that it is a detergent. Its pH is basic: between 9 and 10 when that of the skin is at 5.5.
Soap, ecological and economical

Solid soap is more economical
Much more economical than shower gel, it lasts a long time and costs less.
Liquid soaps and shower gels are mostly water (80%). Since water is conducive to the growth of bacteria, formulators must add preservatives so that they expire less quickly, especially in humid and warm environments such as a bathroom.
Solid soaps , due to their reduced water content (soaps are not waterless as we often read) but above all due to their composition , do not need preservatives.
Moreover, a good soap made according to the rules of the art – which does not crack or melt – lasts for months when a medium-sized shower gel (500ml) rarely lasts more than a few weeks. To say, however, that a soap is cheaper is a bit of an exaggeration. Because, as we will see, a really good quality soap is now an almost luxury item. While the soap sold in supermarkets is certainly cheap, for the most part, of poor quality.
Long live zero waste!
This is largely what has determined the return to grace of the bar of soap: it is (almost) zero waste . A bottle of shower gel – even in recycled and recyclable plastic – consumes tons of plastic, thousands of liters of water, tons of CO2 to be transported, and produces waste that we do not really know if the recycling channels treat correctly (particularly shower gel tubes that are difficult to recycle). Whereas a bar of soap requires much fewer resources for its production, its transport and only requires the recycling of its paper or cardboard packaging, when it is not sold by the cut. Because, if it is produced correctly, it is completely biodegradable.
He is nomadic
The icing on the cake is that the bar of soap, provided it is dried well and placed in a net or metal box, can be easily transported in a toiletry bag when travelling, without worrying about weight or millilitres on a plane.
Soap in the ideal and other soaps….
As we have seen, since Aleppo soap or its descendant from Marseille, times have changed. Industrial or semi-industrial manufacturing methods have profoundly changed the properties of soap. The one you buy for €2 in a supermarket has nothing to do with the one you pay more than €10 for from one of the last real soap makers who masters manufacturing from A to Z.
Industrial soap making causes soap to lose its qualities

Manufacturers have long adopted the "hot" or "cauldron" method of soap making. While this is the method used for Marseille soap, they have transformed it in such a way as to drastically reduce the time taken, and therefore the properties of the soap. Thus, the drying time of the soap goes from one month to one day! This process also has a strong environmental impact in terms of water and energy consumption (it is heated between 100 and 120°C). In addition, the heat requires choosing more resistant ingredients but whose initial production is not ecological , such as palm oil. Finally, the soap is rinsed with salt water to eliminate excess soda, also eliminating the glycerin which is beneficial to the skin.
These industrial soaps are then generally reduced to shavings, the bondillons. However, today, nearly 80% of the bondillons are produced in China or Malaysia and even the soaps stamped "Marseille soaps" are produced mainly in Turkey or China.
These balls are then sent to "semi-artisanal soap factories" that do not actually make their soap but are manufacturers who will only color, mold, perfume, stamp the bars obtained in an extruder and sometimes add a little oil. The proof: a soap that melts quickly or cracks over time is not a good soap. If it softens very quickly, it is because it contains too much water and has not dried long enough during its manufacture. Its "heart" has not had time to harden.
You can still find good soaps made hot, especially in artisanal soaps from Marseille or Aleppo, made with quality raw materials, taking your time, and adding glycerin or oil (hence their name superfatted) during manufacture. You have to pay attention to the place of manufacture and do not hesitate to ask questions to the reseller.
Cold saponification is preferred but rare
As its name suggests, cold saponification is done without cooking. But this method cannot be industrialized, because it requires excellent quality raw materials and a long time, since it takes more than a month to produce a soap. The oils and soda are mixed and emulsified before being put into a mold. Saponification creates an exothermic reaction at 60/65 ° C, which preserves the properties of the oils. Then comes the "cure", that is to say the resting period of the soap which lasts 4 to 5 weeks, during which the soap dries and stabilizes, because saponification continues until one of the reagents (soda or oils) is used up and glycerin is naturally produced during this process. This process is not very water and energy intensive, but the soaps are biodegradable and combine detergent and moisturizing properties since they keep about 10% glycerin as well as the unsaponifiables (as their name suggests, the ingredients that do not become soap): vitamins, terpenes, squalenes, phytosterols, etc. with nourishing, softening, protective, antioxidant effects. The problem: you can't find this type of soap in supermarkets because they are produced by small entities and are sold for more than €5 each.
Is soap really good for your skin?
Who has never left a dermatologist's office and been prescribed to wash with a good Marseille soap? And what can be said in response to this prescription from a skin specialist, who may have forgotten that soap is, by definition, alkaline or basic, and therefore not in line with the pH of the skin ? The proof: when washing with a basic soap (in both senses of the term), you come out of the shower with skin that creaks, that does not slide when you run your hand over it, and becomes rough if you do not assiduously cover yourself with moisturizer.
This is why soap is said to "strip": it damages the hydrolipidic film that protects the skin and the skin dries out as a result. Only soaps that have retained their glycerin can avoid this problem.
But here again, be careful with perfume and essential oils which, even if they are rinsed, can cause reactions on certain very sensitive skins. As for damaged or atopic skins, whose skin barrier is altered, they must be particularly attentive to the composition of the soap they use.
So, should we go back to soap? Yes, but only good old soap, made as it was in the past, according to the rules of the art, with a long manufacturing and drying time, and quality oils, pure and virgin. And not industrial soap, full of water and emptied of its glycerin.
The problem lies in the difficulty of distinguishing a good old soap from an industrial soap, because even the soaps called " Made In France " are, in reality, only made in France! Otherwise, opt for the superfatted bars in the pharmacy.