Of what this soap is made?

   When describing how the ash soap is made Mrs. Rosa said: “First I put the ash there in the bucket. After I, I pound it down with a socket. Therein after that I have pound it very well down, then I put the water. Therein, after I drip the dicuada and after that that I put here into the pan. Put the dicuada there and put the tallow. The tallow or the fat and go, and go mixing. Therein after… then that depurates the soap”.

   On her description, this lady mentioned the use of ash, a bucket, a socket, water, the “dicuada”, a pan and the tallow or fat. She first puts the ashes into the bucket, which contains holes on its base and is lined with a cloth, and pound them down, compact with a socket. After they are “very well down”, well compressed, she puts hot water to obtain the “dicuada”, the solution that comes trickling from the bucket: “Therein after I drip the dicuada”. Although Mrs. Rosa did not mentioned, the women use hot water in this procedure.

Mrs. Maria Celeste putting hot water over the ashes

Mrs. Maria Celeste putting water over the ashes

   As seen, the ashes are not directly used in the soap making:

Rosa: No, if you put the ash it doesn´t generate nothing no. It turns to a thing there, almost nothing.

Aparecida: It doesn´t generate. It can´t pick up the ash. Without the ash. It is from ash and cannot let the ash pick it up.

Anesia: It´s from ash because it´s made of dicuada, right?

   If the ash is used as such it “doesn´t generate nothing”, it does not produce the soap: “It turns to a thing there, almost nothing”. The ashes cannot be  used directly in the mixture: “It is from ash and cannot let the ash pick it up”. They call it black soap, ball soap, a bread of soap, ash soap, dicuada’s soap. “It´s from ash” but “because it´s made of dicuada”: an ash lye.

   To obtain the dicuada Mrs. Rosa uses a bucket, but traditionally it is done with a round hamper made with bamboo strips of varying sizes (of 50 to 100 liters or larger) lined internally with banana tree leaves before placing the ashes. The leaves act as a filter, retain the insoluble part of the ashes but let the solution pass through. They call this device by “barrilero”, which can also be lined with a cloth bag rather than leaves, with the same effect. How did they get to this device? How did they find its application in the soap making? How did they discover the possibility of using banana leaves to retain the insoluble and unnecessary part of the ashes?


Superior view of the barrilero

   However, the procedure to pound down the ashes is reinforced:

Rosa: You have to put in a bucket or in a little hamper and pound it down. And pound it down with a socket to be very well pounded, otherwise it doesn´t get out no. If we put the ash there only and put the water that gets out weeeak.

Aparecida: It does. You have to pound it down. You have to stick it well into the can in order to give strongness to the dicuada. The stronger is the dicuada faster makes the soap.

   The ashes are compacted into the barrilero using a socket or even the hands: “to be very well pounded”. Otherwise, if not well compacted, if not “stick it well into the can”, make it “very well pounded”, if “put the ash there only and put the water” the dicuada “doesn´t get out no”: it “gets out weeeak”, it becomes diluted, low concentrated. In Aparecida´s words this is “to give strongness to the dicuada”, to increase the concentration of the ash lye. This is so because “the stronger”, the highest concentration of dicuada, “faster makes the soap”, quicker will be the saponification reaction rate.

   Thereby, the experience of these women relates the speed of the soap´s making with the “strongness” of the dicuada, which itself will depend on the  high compression of the ashes into the barrilero. Doing this they put greater amount of ashes and the result is that water will cross them slowly.  A larger barrilero may takes an entire day to produce the dicuada or even more than a day.

   The ashes used in the soap´s making usually come from stoves and furnaces fed with wood. This one undergoes combustion in these locations and the final product is the remaining ash. Its composition depends on the type of wood used. Generally, ashes have inorganic compounds from plants and powdered coal produced by combustion. Mrs. Maria Celeste mentioned that certain plants produce more suitable ashes for the soap´s making, such as the wood of “Assa Peixe” – Vernonia polyanthes Less, the bean´s straw – Phaseolus vulgaris, and the coffee´s straw – Coffea arabica. How does she know it?

   The chemical composition of the ash lye from the “Assa Peixe” showed the presence of ions such as potassium, calcium, iron(III), aluminum, carbonate, phosphate, silicate and carbonate levels equal to 40% of the total mass as potassium carbonate, also known as “potash”. It is the substance involved in the reactions that produce the soap and can be observed as white fine grains in the ashes. Its high content attests Maria Celeste´s knowledge about this plant, but how did she acquire this knowledge?

   Thus, they say that they will “drip the dicuada”, to extract the potassium carbonate from ashes by its dissolution in hot water.  The color of the dicuada usually is brown-reddish, which indicates the presence of iron(III) ions, but the women do not know it, what they know is that the concentration of dicuada, its “strongness”, has no relationship with this color neither its intensity. As a matter of fact, the potassium carbonate is a white substance and its aqueous solution is colorless, but the solution acquires another color as iron compounds are dissolved by water in the process.

   Another aspect of these women´s knowledge that is consistent with the chemistry knowledge is that they know that there is a proportional relationship between the amounts of dicuada and animal fat in the soap making. When the dicuada solution is very concentrated in potassium carbonate its quantity may be superior to the required. On the other hand, if it is very diluted it may be necessary to prepare another barrilero to obtain more dicuada. In the first case, the remaining portion can be used again but in a different way:

Aparecida: And this dicuada here if we put it into the pot and let it dry turns a salt.

Rosa: It turns salt. That´s right, I usually put it in a little caldron.

Aparecida: All right. We want to avail we put it to dry. And you can put that salt in other soap. When you´re going to make it, pick that salt and passes to other soap.

Rosa: You have to put it on fire, right?

Aparecida: You have to pass it to the pan and put it to dry. Therein it turns a salt.

Rosa: It gets white the salt, right?

Aparecida: Therein the salt can be stored. When you´re going to make other soap you can take that salt and put on the soap.

   The reutilization of dicuada after its drying on fire (“put it in the pot and let it dry”) occurs in the form of a “salt”. With the boiling of water of the solution, it remains a “salt”, the residue containing the dissolved compounds from the ashes that re-crystallized “in the pot”, the “little caldron” or in the “pan”. They say that “turns a salt”, crystallizes a residue. The fact that “it gets white the salt” and “you can take that salt and put on the soap” shows the presence of the potassium carbonate in the evaporation residue, which is also a salt for the chemists, an inorganic white color salt, which “can be stored” and used to prepare another soap.

   Did they discover that accidentally? Did they observe this salt production by chance in the natural drying of the dicuada and after that experiment to use it? How did they make the relationship between this salt and its use in the soap´s making? Was the experimentation their guide of these women, or the curiosity and the logical reasoning allied to experimentation? Nevertheless, isn´t it something that is more usual between chemists or scientists?

   Despite the possibility to reuse the dicuada in the form of “a salt”, the ash soap is rarely made using only the remaining residue from its drying. The regular is to use the ash lye, as Mrs. Rosa said: “Put the dicuada there and put the tallow, the tallow or the fat and go, and go mixing. Therein after… then that depurates the soap”.

   Another procedure of the women that is certified is the use of hot water to obtain the dicuada. Hot water favors the dissolution of potassium carbonate as it is endothermic (Dean, 1987). When dissolved in the water, this substance is dissociated and the carbonate anion undergoes hydrolysis turning the dicuada solution alkaline:

dissolução da potassa e hidrólise do carbonato

   The tallow comes from the cow or ox and the fat from pork. They are solid materials at the temperature of 77° Farenheit. Both contain triglycerides, as the tristearin or glyceryl triestearate, for example, and small amounts of free fatty acids. Most of these is found in the combined form of triesters, which decomposes in alkaline aqueous medium releasing acids as myristic, palmitic, palmitoleic, margaric, stearic, oleic and linoleic, which will react with the potassium carbonate from the dicuada and produce soaps. The tallow of ox usually contains higher amounts of stearic acid (octadecanoic), palmitic (hexadecanoic) and oleic (octadec-9-enoic acid).


Typical formula of a triglyceride, where R (chain of carbon atoms) may vary


Structural formula of triestearin


Acid stearic

Acid oleic

This is similar to how modafinil online works and how modafinil http://www.modafinilonline247.com/ online works online.

Go to: “Where’s the fat in the pot?

Back to: Persistence, changes and relationship with the early soaps


Dean, J.A. (Ed.) (1987). Lange’s Handbook of Chemistry. 13. ed. New York, Tab.10-2, 10-15.

2 thoughts on “Of what this soap is made?

    1. Paulo Pinheiro Post author

      depende do filtro/tecido. Tente obtê-la no filtro que você tem à disposicão, vamos ver o que acontece… Não pode deixar passar a cinza, lembre-se…


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