KAOLIN

In this complete guide on kaolin or white clay we explain everything about a material with countless benefits and different applications, apart from its use in ceramics.

Some of them will surprise you for sure.

WHAT IS KAOLIN?

Kaolin is a light-colored earth very rich in kaolinite. Because of its color it is also called white clay, so to speak of kaolin or white clay in this case would be the same thing. The whiter its color, the greater its purity, since it would be free of materials such as oxides or elements of vegetable origin.

And what is kaolinite?

Kaolinite or kaolinite is a mineral, it belongs to the silicate class (subclass of phyllosilicates and kaolinite-serpentine group, for those who are interested in something more technical).

It occurs naturally in loose or compact earthy compounds, forming sheets.

It is a common component to other types of clay, such as “ball clay“.

Where this prized white clay comes from:

The name of the clay kaolin comes from the French kaolin, in turn from the Chinese kao-ling shan 高岭 山, this is the name of a mountain (shan 山 means mountain) in Jianxi province, towards the east of China, this area is also known as porcelain land. Hence it also receives the English name “China clay”. Although its name comes from this first location, there are obviously kaolin deposits in many other parts of the world (e.g. in Africa it is called Kalaba).

It is one of the most appreciated materials used in ceramics, fortunately it is relatively abundant in the earth’s crust. You can imagine how old it is…, depending on the sources that talk about this material and its deposits, several ages are considered, but the great majority of them do not go below 100 million years.

Chemical composition of kaolin:

Es un silicato de aluminio. Su fórmula sería:

• Aluminum oxide (Al2O3). About 40% of the
• Silicon oxide (SiO2). About 45% of
• Water (H2O). The remaining 15%.

PROPERTIES OF KAOLIN

• It is whitish, hence it is known interchangeably as kaolin or white clay. However, it may not be pure and the other elements present may, logically, give it color; it is also matte.
• Kaolin is of low hardness, grade 2 on the Mohs scale. If this does not tell you much, to give you an idea, it would be similar to gypsum, you could scratch it with your fingernail. It is closer to talc in terms of hardness than to many other clays.
• It is odorless.
• Very absorbent.
• The pH of kaolin clay is NOT neutral, as it is read in many places, but a little acid. What happens is that its pH (between 4 and 6) is similar to that of human skin (between 4.7 and 5.75) which is also acidic, hence the confusion. The neutral pH is 7.
• It can have an unctuous feel, this and other characteristics of kaolin will logically depend on the proportion of kaolinite it contains; the higher the percentage of solids, the lower the viscosity.
• The economic benefit it brings, for example in Spain, in terms of its use in ceramics, even though it is used in smaller quantities than other clays, accounts for more than two thirds of the total value of the clays that are marketed. Its multiple properties in terms of benefits for the human being give it many utilities that we will explain below.

WHAT IS KAOLIN USED FOR

It is a material whose properties make it suitable for a lot of different applications, very numerous and varied.

USES OF KAOLIN IN CERAMICS:

The application that we emphasize here is its use as a material to make porcelain and thus all kinds of pieces called as such, with functions such as decorative figures, or that may also have some utility, such as vases, cups and plates for all types of tableware, etc.. As well as to manufacture sanitary ware.

When kaolin is part of ceramic materials, which are the result of firing this earth, it gives them plasticity. It also confers great resistance to firing and after firing, in the final result. Let us not forget that one of the keys of porcelain is that it is a ceramic that is fired at high temperatures. On the other hand, it gives control in the shrinkage or contraction of the pieces.

Because of this relationship with heat, the final ceramic objects are refractory.

In addition, they do not have any water absorption.

However, outside the field we are dealing with, kaolin clay has an infinite number of other uses, let’s take a look at them.

INDUSTRIAL APPLICATIONS OF KAOLIN:

As refractory material:

It withstands high temperatures, even for long periods of time. It does not expand or contract too much in what is called “thermal shock”. It is one of the ceramics used as a thermal insulator, since it prevents the propagation of heat.

Kaolin as an electrical insulator:

Ideal as a component of insulating ceramic elements (mostly porcelain) in many installations. In addition to avoiding any conduction of electricity, it is what is called “chemically inert”, i.e. it does not react with electricity.

In the paper industry:

Included in its composition, kaolin improves printing and gives smoothness, whiteness and brightness to the leaves.

The low viscosity and brightness it brings to the paper makes it very effective also in the coating of sheets that are intended for photographic printing and where a good brightness in color printing is needed.

Kaolin in the manufacture of ink

To improve its retention. It has another advantage, that being of very low hardness it is hardly abrasive, so that when used in inks used in the press, the printing plates are hardly affected or damaged over time. The kaolin in the ink helps it to remain on the surface that has been printed.

In paint:

Performing the functions of what is called a pigment extender, what it does is to modify the gloss, texture and properties of the final product adapting them to the manufacturer’s needs and without color modification problems. Widely used in exterior base paints, with an oil-based composition.

The use of kaolin in paints facilitates the elimination of stains during washing. It prevents enamels from penetrating into the interior of the objects to be treated.

Rubber industry:

It gives the final product rigidity and resistance. This clay is ideal for pigmenting and is not very expensive compared to other dyes. More than 700,000 tons of kaolin are used annually in this sector.

Plastics manufacturing:

It is mainly in PVC where kaolin is used the most. It gives smoother surfaces, and prevents excessive shrinkage that causes parts to crack. It also gives them greater strength.

In agriculture:

Kaolin is used as a natural insecticide and aids in pest control. By creating a protective film when applied to plants, it prevents water loss in times of low humidity and insulates from heat, preventing excessive evapotranspiration, minimizing the amount of radiation reaching the plants.

Kaolin in construction:

It is a fundamental material for the manufacture of sanitary ware, due to its low porosity. It is used in other ceramic materials for construction, such as roof tiles, tiles, tiles, both as part of its structure and as a coating to give greater resistance to the elements.

Here is an interesting and complete video on the manufacture and uses of kaolin:

WHITE CLAY IN COSMETICS:

Kaolin has been used for aesthetic purposes since the earliest civilizations, such as ancient Egypt. We explain what kaolin is used for in the skin and what other uses it has in aesthetics and hygiene in general.

As a facial mask, this clay helps to regulate the level of oil in the skin, so although it is suitable for all skin types, it is recommended for oily skin, due to its seboregulating properties. Because of this it can also help in the treatment of acne, thanks also to its antiseptic qualities.

Kaolin is a clay that also causes exfoliation, eliminating dead cells, although the particles, being fine, are not too abrasive to the skin, so they are indicated for sensitive skin for which other clays would be too aggressive. It is recommended for young skins that are fine, taking into account that the tendency of these to be oily is more frequent at this age.

It is nourishing for the skin due to its mineral components.

It is even used to make shampoo by mixing it with baking soda and Maizena (cornstarch flour). It is a dry shampoo that is applied to the hair with a brush and, after about ten minutes, is removed by brushing the hair.

As a natural deodorant, due to its antibacterial characteristics, it provides dryness against sweat and prevents odor. It is also mixed with cornstarch and in this case some fatty substance is added (such as some oil or butter) and some other substance that gives aroma, such as an essential oil.

It has even been attributed with properties to reduce skin blemishes, wrinkles, and to help with psoriasis and stretch marks.

Kaolin is included in making natural toothpaste, being alkaline, antibacterial, anti-inflammatory, because of this there are many recipes for making homemade toothpaste with this white clay. They usually include in addition to this ingredient, baking soda, coconut oil and a little bit of some essential oil of mint, to give a fresh flavor. Sometimes aloe vera and/or unrefined sea salt are added. If you are interested, here are several options.

KAOLIN FOR MEDICINAL PURPOSES:

Kaolin is attributed with many medicinal properties. It goes without saying that any of them should be taken with caution and always under the advice of licensed professionals.

• In the pharmaceutical industry it is used as an excipient in drugs.
• As a bactericide.
• As it is molecularly arranged, it has a great power of absorption, as we mentioned, so it is also used to treat digestive system problems such as colitis. Laboratories include kaolin in their formulations, not only as an excipient, but also as an active ingredient, mixed with pectin (vegetable fiber that helps to eliminate toxins from the body) or methylcellulose.
• Healing and anti-inflammatory properties are attributed to it.
• There are countless treatments in natural medicine that include it.

CALABACHOP: EDIBLE KAOLIN?

Yes, kaolin is eaten . There is a widespread custom especially in Africa, in Equatorial Guinea where the edible kaolin is known as calabachop; it is also eaten in Cameroon, Senegal and Gabon where it is called Kalaba. This tradition is also found in areas of the U.S.A. where there is an African-American population, as well as in Haiti.

Eating kaolin or any other earthy material (known as geophagy) has been a habit or instinct throughout the evolutionary history of humans and their ancestors. This can be observed in the behavior of some young children.

Ingesting kaolin is more common in the female population and during pregnancy. This is done because it is attributed with beneficial properties for the digestive system and it is claimed to eliminate the nausea that occurs during pregnancy, supposedly protecting the stomach against pathogens, parasites and toxic substances. For this reason, kaolin and pectin (a vegetable fiber that helps eliminate toxins and waste) are sometimes used for gastrointestinal problems.

Thus, calabachop is edible kaolin, in various forms, however, you should always check the scientific evidence on the medicinal benefits of this land and consult with a physician; on the other hand, it has been published that it could hinder the absorption of iron, so that, if so, would generate anemia.

It’s all about research and “testing”. In Naturalica you can buy edible kaolin.

What does calabachop taste like?

Anyone who has tried these materials will say that they are grounded.

How do you eat calabachop?

Although it is usually stored in stones, as it is a very soft material, it can be bitten and chewed directly. Although there are those who add it to food, in crushed form, in a teaspoon.

WHITE CLAY FOR RELIGIOUS PURPOSES

This is perhaps not so well known: Kaolin is also used in religion! Yes, in Afro-Cuban practice. In the Yoruba culture it is known as Efun. The Yoruba people are originally from West Africa, elements of their culture have reached other parts of the world.

You can see here an interesting video, in relation to these last uses we have told you about this clay, about the elaboration of the so called “blessed earth bread”.

BUY CAOLIN

You will have no difficulty in finding where to buy it. However, it will depend on the use you want to give it, and the amount you need, since that need will range from small amounts to test a cream, something more for artisan porcelain work, more if it is industrial and beast if you are a builder (we do not believe …, but if it were the case, in quiminet.com there is a list of exporters).

Remember to look for “white clay” in addition to kaolin.

You can buy kaolin for cosmetics, masks, soaps, etc. from Foundin Bio.

For use in ceramics, and in an artisanal way, of course, you can find it in online stores like Marphil, in Naturclay (more focused on construction, they sell bags of 20kg. and up).

It will depend on the amount you need and the purity required for your work.

Pricing:

There is quite a lot of supply of this white clay and many online sales sites where to find it, add that if you look around there are good deals on the Internet for one reason: Kaolin is in great demand in many different sectors (some of great competition such as cosmetics), which will benefit you when it comes to easily find quality products at a good price, which will not happen with other very specific materials. Translated with www.DeepL.com/Translator (free version) To give you an idea, copying a kilo of kaolin for pottery separately, prices can range from €1.80 to €4, depending on the quality, for example, a kaolin already treated with great whiteness such as Moloquite, is more expensive.

Tip:

For ceramic works that do not require the quality of cosmetic kaolin, do NOT pay more than €5 for a medium quality and in the 1Kg size.

We also leave you here some summary questions about this article:

What is kaolin?

Kaolin is a light-colored clay very rich in kaolinite. It is also called white clay because of its color. The whiter it is, the greater its purity, since it would be free of oxides or elements of vegetable origin.

What is kaolin used for?

In ceramics, it is key to making porcelain. It has countless industrial applications, among others, to make paper or ink. It is widely used in cosmetics, for example to make masks, deodorant, toothpaste or shampoo.

What is kaolinite?

A mineral of the silicate type. It forms part, in high quantities, of kaolin and ball clay. It occurs naturally in sheets and is also widely used in industry and agriculture.

Is it true that kaolin is eaten?

Yes! One of the lesser known and seemingly surprising uses is to eat it. However, in African traditions it is common to eat this material, which is also known as calabachop. It is also used in religion.

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