Raw materials for the ceramics industry: the definitive guide

Choosing the right raw materials for the ceramics industry is no minor decision. A poor initial selection can result in irregular shrinkage, warping, cracking, absorption issues, shade variations, reduced strength, or higher energy costs.

In industrial ceramics, the final result begins long before a finished tile is seen. It starts with the raw material—its behaviour, its blending, and how it responds during forming, drying, and firing.

Because a high-value ceramic piece is not born from design alone. It is born from a well-formulated base.

In this article, you will learn:

• Ceramic raw materials are the starting materials that undergo transformation during the ceramic process to achieve a fired, hardened product.

• In traditional ceramics, these are typically classified by their function into plastic materials, non-plastic materials (shortening agents), and fluxing materials.

• Clays, quartz, and feldspar form the classic foundation of many industrial ceramic compositions.

• Fluxes are key because they assist in the formation of the glassy phase and can influence both the firing temperature and energy costs.

• Kerafrit draws on its expertise in these raw materials to develop high-added-value solutions such as frits, glazes, grits, inks, protections, additives, and process solutions.

What are ceramic raw materials and why is their correct selection crucial?

Ceramic raw materials are the starting components used to manufacture a ceramic piece. Throughout the process, these materials are prepared, mixed, shaped, dried, and fired until they transform into a stable, hard, and resistant final product. The ceramic process is essentially a transformation of starting materials through stages such as selection, preparation, moulding, drying, and firing.

Put simply: the raw material is where everything begins.

If the base is not correctly chosen, problems can arise at any stage—during body preparation, pressing or extrusion, drying, firing, surface finishing, or in the final performance of the tile or ceramic piece.

A composition may look correct on paper, but if it does not perform well on the factory floor, it is no longer viable. That is why, in the ceramics industry, it is not enough to simply know the materials. You must understand how they behave together.

A good selection of raw materials helps to achieve:

• Greater dimensional stability.

• Improved green strength.

• Lower risk of cracking.

• Controlled water absorption.

• More efficient firing.

• More consistent finishes.

• Reduced production waste.

• Greater predictability of the final result.

In short, the raw material dictates the quality, cost, and innovation potential of the ceramic product.

The fundamental classification of ceramic raw materials

To understand ceramic raw materials, we can imagine them as the ingredients of a recipe.

There are ingredients that provide body, others that control the structure, and others that help everything bond together during firing. In ceramics, this logic translates into three main groups:

• Plastic materials, which provide workability, cohesion, and green strength.

• Non-plastic materials or shortening agents, which help control shrinkage, warping, and stability.

• Fluxing materials, which promote vitrification and help close the structure during firing.

This functional classification is a very practical way to understand how a ceramic body is constructed. Technical sources usually distinguish between plastic raw materials—mainly clays—and non-plastic materials, which can act as either shortening agents or fluxes.

Plastic materials: the skeleton and workability

Plastic materials are what allow the body to be worked. They provide cohesion, formability, and strength before firing.

They are essential in processes such as pressing, extrusion, or casting, as they help the piece maintain its shape in its green state.

Within this group, we mainly find:

• Kaolins.

• Ball clays.

• Common red clays.

• Bentonites, for specific uses.

Non-plastic materials or shortening agents: dimensional control

Non-plastic materials do not provide plasticity, but they are essential for balancing the formula. They help reduce excessive shrinkage, improve drying, and control dimensional behaviour.

They act as the balancing point of the recipe. If there is too much plasticity, the piece may warp, crack, or shrink more than desired. Shortening agents help maintain control.

This includes materials such as:

• Quartz or silica.

• Grog (chamotte).

• Sands.

• Alumina.

• Corundum.

• Certain recycled or calcined materials.

Fluxing materials: the catalysts of vitrification

Fluxes help a glassy phase form during firing. This glassy phase acts as a sort of internal bond: it promotes densification, reduces porosity, and contributes to the final strength.

Feldspar is one of the most common fluxes in ceramics. IMA-Europe explains that feldspars act as fluxing agents, forming a glassy phase at lower temperatures and helping to improve the strength, hardness, and durability of the ceramic body.

In this group, we find:

• Potash feldspars.

• Soda feldspars.

• Nepheline syenite.

• Talc.

• Dolomite.

• Wollastonite.

• Carbonates, depending on the composition and type of product.

Plastic materials: the heart of the ceramic body

Plastic materials are the heart of many ceramic compositions. Their primary function is to provide workability to the body and allow the piece to retain its shape before it enters the kiln.

In practice, they help solve a fundamental need: ensuring the material can be formed without breaking, warping, or losing cohesion.

Kaolins: purity and whiteness for bodies and glazes

Kaolin is a highly valued raw material when whiteness, purity, and control are required. It is used in white bodies, porcelain tiles, sanitaryware, glazes, and other applications where the final colour and stability are important.

It provides alumina and silica, and is typically associated with compositions where a cleaner and more controlled result is sought. Regarding white-body porous wall tile compositions, Qualicer notes the use of clays with low iron content and the introduction of kaolin when greater whiteness is required.

In practical terms, kaolin helps when we want:

• Whiter bodies.

• Greater colour control.

• Good firing stability.

• Cleaner formulations for products with high aesthetic demands.

However, it does not always provide maximum plasticity. For this reason, it is often combined with other clays that improve the workability of the body.

Ball clays: maximum plasticity and mechanical strength

Plastic clays, also known as ball clays, are extremely useful when there is a need to improve plasticity, cohesion, and green strength.

Their role is very clear: they help the piece better withstand handling before firing.

This is especially important in industrial processes where the piece passes through several stages before reaching the kiln. A body with low green strength can lead to breakages, downtime, waste, and a loss of efficiency.

Ball clays typically provide:

• Better forming properties.

• Increased cohesion.

• Higher strength before firing.

• Improved behaviour in pressing or casting processes.

• Greater safety during handling.

Balance is important. A clay that is too plastic can increase shrinkage or make drying difficult if it is not well-balanced with other materials.

Common red clays: versatility for extrusion and single-firing products

Common red clays have a long tradition in the manufacture of ceramic products, especially in construction components, floor tiles, wall tiles, and red-body products.

Their colour is primarily due to the presence of iron oxides. In Spain, the availability of natural red clays has historically influenced the production focus towards red-body tiles.

They are versatile raw materials, readily available, and perform well in many industrial applications. They are used in products where whiteness is not a priority and where a good balance between technical performance, cost, and availability is sought.

They provide:

• Good forming capacity.

• Versatility across different processes.

• Suitability for extrusion and single-firing (monocottura).

• Competitive cost.

• Availability in specific production regions.

Their selection must be carefully controlled, as the natural variability of clays can influence colour, shrinkage, carbonate content, plasticity, and firing behaviour.

Non-plastic materials: ensuring structural stability

Non-plastic materials are fundamental to prevent the body from behaving in an excessively “live” manner. In other words, they help control shrinkage, reduce internal stresses, and improve dimensional stability.

In production, this is key. Many issues arise when the piece dries or fires irregularly: cracking, warping, out-of-range sizes (calibres), curvatures, or flatness problems.

Shortening agents help make the composition more stable.

Silica or quartz: the regulator of expansion and structure

Silica, usually in the form of quartz, is one of the most important non-plastic raw materials in ceramics.

Its primary function is to help control the structure of the body. It can influence shrinkage, porosity, strength, and thermal behaviour. A technical dictionary of ceramic raw materials from Valdosta State University notes that silica or quartz is used in ceramic bodies to modify shrinkage, porosity, and strength, depending on particle size and crystallinity.

Put more simply: quartz helps ensure the body does not move more than necessary.

However, it also requires careful control. Quartz undergoes thermal transformations that can generate stresses if the composition is not well-balanced. Therefore, it is not just about adding quartz, but using it with sound judgement.

Alumina and corundum: for high-strength and refractory applications

Alumina and corundum are used in applications where superior performance is required: higher strength, better performance at high temperatures, or greater refractoriness.

These are not raw materials used in every standard composition, but they play a vital role in technical or more demanding products.

They can provide:

• Increased hardness.

• Greater wear resistance.

• Improved thermal behaviour.

• Enhanced stability in demanding applications.

In technical ceramics, the use of oxides such as alumina is common in high-performance formulations. The European BREF document on the ceramics industry includes alumina among the materials used in technical ceramics, alongside other oxides, carbides, nitrides, and borides.

Grog (Chamotte): the recycled raw material that provides stability

Grog is fired and crushed clay that is incorporated into new ceramic compositions to improve the stability of the body.

Its value lies in the fact that it has already undergone a thermal process. Therefore, it behaves more stably than raw clay. It helps reduce shrinkage, facilitate drying, and improve dimensional behaviour.

In simple terms, grog provides “thermal memory” to the composition.

It can be used to:

• Reduce shrinkage.

• Improve drying.

• Decrease internal stresses.

• Provide texture or body.

• Promote the reuse of ceramic material.

Furthermore, it aligns with a very relevant industry trend: the recovery of internal waste and secondary raw materials. The European ceramic roadmap indicates that using internal production waste as a substitute for raw materials is common practice in Europe for bricks, floor tiles, and wall tiles.

The role of fluxes in the firing process

Fluxes are essential because they help ceramics achieve vitrification.

Vitrification is the process by which part of the composition forms a glassy phase during firing. This phase helps bond particles together, close pores, and provide greater compactness to the final product.

In simple terms: the flux helps the piece “seal” or bond better during firing.

This has a direct impact on:

• Water absorption.

• Mechanical strength.

• Densification.

• Firing temperature.

• Dimensional stability.

• Energy costs.

This is a key industrial factor: if the flux allows for operation at an appropriate temperature and with a good firing curve, it can help improve process efficiency. However, if the composition melts too much or in an uncontrolled manner, it can lead to warping, variations in calibre, or stability issues.

Qualicer points out that, in vitrified (stoneware) compositions, the proper formation of a glassy phase is necessary, but excessively low viscosity can cause firing deformations.

Potash and soda feldspars: the primary fluxing agents

Feldspars are arguably the most well-known fluxes in the ceramics industry.

They act by promoting the formation of a glassy phase, which helps densify the ceramic body. IMA-Europe indicates that, in ceramics, feldspar is the second most important ingredient after clay and that it facilitates the fusion of quartz and clays during firing.

Depending on the composition, the following are mainly used:

• Potash feldspar, associated with specific firing responses and glassy phase formation.

• Soda feldspar, which generally exhibits more active fluxing behaviour.

• Mixed feldspars, used when seeking to balance technical performance, cost, and availability.

Their selection influences the maturation temperature, compaction, water absorption, and dimensional stability.

Nepheline syenite: higher fluxing power for fast cycles

Nepheline syenite is used as an alternative or supplement to feldspar in certain compositions.

It possesses high fluxing power, which can be advantageous when aiming for faster firing cycles or lower maturation temperatures.

It can offer benefits such as:

• Increased fluxing capacity.

• Lower vitrification temperature in certain compositions.

• Excellent response in white-body formulations.

• The ability to fine-tune production cycles.

As with any flux, its use must be correctly formulated. Excessive fluxing can compromise dimensional stability or cause warping.

Talc, dolomite, and wollastonite

In addition to feldspars and nepheline syenite, other materials can act as fluxes or composition modifiers.

Talc, dolomite, and wollastonite provide oxides that influence behaviour during firing. Their role can vary depending on the product type, temperature, firing curve, and other raw materials.

In practical terms:

• Talc can help modify fluxing and thermal behaviour.

• Dolomite provides calcium and magnesium, affecting the glassy phase and firing.

• Wollastonite can contribute calcium and silica, while also influencing stability and dimensional behaviour.

These are not “good” or “bad” materials in themselves. Their value depends on how they are integrated into the formula.

From raw material to solution: how Kerafrit creates added value

Raw material is the starting point. However, true value emerges when that knowledge is transformed into solutions that solve real production, design, and performance challenges.

At Kerafrit, mastery of the material base enables the development of technological products such as:

• Frits.

• Glazes.

• Grits.

• Micro-grits.

• Inks and digital effects.

• Technical protections.

• Anti-slip solutions.

• Additives.

• CMC.

• Deflocculants.

• Anti-foaming agents.

• Rheological modifiers.

• Body binders.

These solutions are not merely “intermediate products”. They are tools used to improve the surface, stabilise processes, provide performance features, and open up new design possibilities.

For example, Kerafrit structures solutions linked to surface aesthetics, anti-slip grip, surface resistance, and production process stability. The company also develops solutions aimed at reducing energy costs through deflocculants and body binders, impacting the optimisation of the ceramic body and gas consumption per square metre produced.

The message is clear: knowing the raw material is not just about formulation. It is about anticipating problems.

It is about knowing why a surface does not respond the same way on the production line as it does in the laboratory. To adjust a glaze. To improve a grit. To achieve a more stable texture. To avoid defects. To increase productivity. To reduce costs without losing quality.

Furthermore, in a context where certain critical raw materials directly or indirectly affect frits, glazes, pigments, inks, and decorative effects, technical expertise and resource efficiency become even more vital. A 2024 study on critical raw materials in the ceramics industry notes that the production of inks, pigments, dyes, effects, frits, and glazes is exposed to supply risks, and recommends strengthening the value chain and improving resource efficiency for specific materials.

This is where Kerafrit adds value: not only through the product but through a deep understanding of how each material behaves within the ceramic process.

The foundation of innovation in the ceramics industry

Raw materials for the ceramics industry are much more than just the start of a formula. They are the foundation upon which the quality, stability, efficiency, and innovation capacity of every product are built.

Clays provide plasticity and body. Non-plastic materials help control the structure. Fluxes allow the firing process to transform that mixture into a resistant, stable, and functional piece.

However, true expertise lies in knowing how to combine them.

Because a ceramic body is not just a sum of ingredients. It is a balance between material, process, and result.

And when that balance is mastered, new possibilities open up: more technical surfaces, more expressive finishes, more precise textures, more efficient solutions, and ceramic products with higher added value.

At Kerafrit, we understand the material from within to help you transform every project from the surface up.

The soul behind the surface.