Sedlec la is the most well-known and oldest product made by Sedlecký Kaolin, a.s. It has been produced since 1892, when Zettlitzer Kaolinwerke AG was founded. Today’s Sedlecký Kaolin, a.s. is its successor.

Kaolin parameters

A product quality control system in accordance with ISO 9001:2000 has been in place since 1998. It exactly defines measuring and calibration procedures and methods. The quality control system certification provides customers with a very reliable guarantee of the given contractual parameters without any need to inspect the actual delivery.

Comparison of different kaolin types

Kaolin for ceramics – recommended use

  • application above 1,300 °C: suitable – Sedlec Ia, Imperial
  • application up to 1,250 °C: sufficient – MK, MK II, MK III
porcelain utility use, hotel use, decorative Sedlec Ia, KN-1, KSA, KSH, KN-2
other utility ceramics
sanitary ceramics
Sedlec Ia, Imperial, MK II, KN-2, MK, KT-M, US 2, clay S1
technical ceramics
Sedlec Ia, Imperial, KSA, KSH, OTK
heat-resistant materials Sedlec Ia, KPO, KN-1, OT 76, MK III
production of glazes and frits, enamels and engobes Sedlec Ia, Imperial, KN-1, POG
construction ceramics MK, MK II, MK III, Thermal, U-ex, U IIIa, semi-mass

Kaolin for paper and dispersions

fillers for the paper-producing industry
OT 76, OT 80, OT 82, KNP, KN-1
U-ex, OT 80 ground, MK ground, MK III



Kaolin for fillers and bonding agents

glass fibres, rubber mixtures, fillers for plastics MK ground, OT76 ground
bonding agents for insulation materials
abrasives, welding electrodes
Sedlec Ia ground, MK ground
bonding agents for pencils
cosmetic additives
Sedlec Ia /bulk and ground, Kolloid

We can provide more exact kaolin parameter specification upon request.

Kaolin origin

Kaolin is a pliable raw material, particularly formed by a clay, the mineral kaolinite.

The key raw material of Sedlecký Kaolin, a.s. can be found in the Karlovy Vary region where kaolin has been mined for over 200 years. Additional kaolin deposits are located in the Podbořany, Cheb and Znojmo districts. Sedlecký Kaolin, a.s. also mines clays and natural sandstone as secondary raw materials.

We achieve the economic and high-quality processing of raw materials into semi-finished and final products by employing modern technological procedures. Our competitive advantage lies in the utilization of purely natural kaolin processing procedures.


Kaolin forms an initial raw material for the ceramics industry and for paper production. Nevertheless, it is also used in many applications in the chemical and other industries.

Sedlecký Kaolin, a.s. produces washed kaolin, which can be further processed into calcinated fillers and heat-resistant sharpeners. Only environmentally-friendly technological procedures are used for processing raw kaolin into washed kaolin.

The following is the theoretical composition of kaolinite:

Al2O3 .2 SiO2 .2 H2O (39.5% Al2O3, 46.5% SiO2, 13.9% H2O by annealing)

Kaolinite is formed of plate particles (usually 1 µm long and 0.1 µm thick) arranged in clusters or blocks (packets), which are firmly or less firmly held together. Kaolinite particles make strong bonds with water which, together with their basic shape, is the cause of its pliable behaviour when in contact with water.

The chemical composition of kaolin is close to that of the theoretical kaolinite, depending on its purity. Its physical and technological characteristics are greatly influenced by the character of the basic plate particles and their blocks – size, shape, presence of various substances absorbed by the particles, etc. The differences in the technological characteristics of various kaolins are thus much greater than the given chemical composition differences.

The kaolins in the Karlovy Vary region were created by the hydration of feldspars which, together with silica, form the basic component of several rocks, particularly granite. The theoretical composition of the main feldspar form is K2O.Al2O3 .6SiO2; its transformation changes it into kaolinite and another silica; the alkali components are mostly infused.

The initial material of the raw original kaolin is granite rock created by volcanic activity when the Earth’s crust was being formed. This original material eroded millions of years ago and broke down into kaolin and silica, accompanied by larger or smaller volumes of other components. The tropical climate at that time exposed the rock to mechanical erosion. Moreover, chemical corrosion was also taking place under increased temperatures due to water saturated with CO2 and rock acids infused from the soil.

The deposits in the Karlovy Vary region are primary deposits – the kaolin has remained at its location of origin. The original granite rock texture is clearly visible even today when mining the raw material clods.

The mined raw material includes 20-30% kaolin; the rest is silica sand, which forms an inseparable part of the raw material. The transformation degree (kaolinization) of the original rock decreases with increasing depth. Only raw material with at least 20% kaolin is usually mined. Tectonic forces meant that the original granite massif in the Karlovy Vary region was frequently disturbed at the time of its origin. Individual granite blocks would divide only when the common magma solidified, whereupon they eroded under very different conditions. The process created many kaolin deposits with different chemical and physical characteristics, sometimes even located quite near each other.

Washed kaolins and Sedlec Ia

Malířský nátěr Unalex U je univerzální otěruvzdorný malířský nátěr se zvýšenou bělostí a kryvostí určený pro malování vnitřních typů omítek, sádrokartonů, sololitu nebo dřevotřísky. Je součástí systému značení Abeceda malování vyvinutého společností Sedlecký kaolin a. s. pro lepší orientaci zákazníka.

Fired kaolins and mixtures

Malířský nátěr Fasadacolor F je určen pro venkovní vyzrálé omítky a betonové stěny s vysokou stabilitou vůči účinkům vody i slunečního záření. Je součástí systému značení Abeceda malování vyvinutého společností Sedlecký kaolin a. s. pro lepší orientaci zákazníka.

Kaolin Sedlec Ia

Malířské nátěry Superlex jsou určeny pro interiérové použití s různou intenzitou bělosti a odolnosti pro různé typy interiérů. Jsou součástí systému značení Abeceda malování vyvinutého společností Sedlecký kaolin a. s. pro lepší orientaci zákazníka. Při výrobě Superlexu se uplatňuje systém řízení jakosti dle ISO 9001:2000.

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