Does the colour of a tile’s body tell us anything about its quality, strength or performance? With both types widely available in the market, and a renewed interest in clay as a material, these questions have sparked discussion across the industry.
To understand the science behind the colour and to separate perception from technical facts, we spoke to Dinesh Vyas, Senior Vice President at H & R Johnson (India), a building materials expert and author of the book, ‘Modern Ceramic Tiles: A Handbook for Professionals’. He explains what determines a tile body’s characteristics, how the body and surface contribute to performance, and what architects and interior designers should look for when specifying tiles.
[IN]SIDE: What constitutes the body of a ceramic tile?
Dinesh Vyas: A ceramic tile body is made from a carefully formulated blend of clay, quartz (silica), feldspar, and other minerals. Each ingredient has a specific role. Clay provides plasticity for forming the tile. Quartz helps control shrinkage and dimensional stability, while feldspar acts as a flux during firing, helping the body densify and develop the required properties. The proportions of these materials vary depending on the type of tile being manufactured and the properties required in the finished product.
Ultimately, it is the formulation, the firing process, and the resulting structure of the body that influence its technical characteristics, not its colour alone. There is no single recipe for each category, but the formulation generally changes with the required water absorption and firing behaviour.
The ISO (International Organization for Standardization) classification for dry-pressed tiles (Group B) provides a useful reference:
| Tile Group | Water Absorption (WA) |
| B-Ia | ≤ 0.5% |
| B-Ib | > 0.5% to ≤ 3% |
| B-IIa | > 3% to ≤ 6% |
| B-IIb | > 6% to ≤ 10% |
| B-III | > 10% |
These limits describe the finished tile’s water absorption, not its raw-material recipe.
The B-Ia group (also referred to as ‘Porcelain’ tiles) achieves extensive densification with high firing (sintering) temperature and appropriate body composition. It is not technically correct to assign a fixed clay, quartz or feldspar percentage to a water absorption group. The recipe is engineered to achieve the desired fired properties. The resulting water absorption is then measured and classified.
[IN]: What makes a tile body white, red or grey?
DV: Body colour depends on the raw-material composition, the chemical form of iron, and the firing conditions. Under suitable oxidising conditions, iron-bearing constituents can develop red colour through the formation of hematite, while different compositions and firing conditions can produce grey, whitish light colour or darker shades.
But remember, body colour can also be deliberately engineered by adding suitable pigments to the body composition. For example, in full-body tiles with a deliberately coloured body, pigments may be added to achieve the intended colour throughout the body rather than relying solely on the natural colour of the raw materials.
Therefore, body colour may result from the natural characteristics of the raw materials, firing conditions, deliberate pigment addition, or a combination of these factors. Body colour alone cannot establish the composition, quality or performance of a tile. Different raw materials, proportions or firing conditions achieve different body colours. These changes can influence vitrification, porosity, and the resulting microstructure.
[IN]: How do the raw materials used in the tile body influence a tile’s performance?
DV: Raw materials influence how a body forms, dries, and vitrifies during firing. Their composition affects porosity, water absorption, shrinkage, dimensional stability, and mechanical strength. The relationship is complex. What matters is how the complete formulation behaves during firing and the properties achieved in the finished tile. A particular ingredient or colour does not automatically guarantee a particular performance level.
[IN]: If red and grey body tiles can both meet porcelain (B-Ia) requirements, does body colour and top surface affect their performance?
DV: Red and grey body porcelain tiles (B-Ia) can both achieve the required water absorption classification. However, B-Ia classification alone does not guarantee identical strength, wear resistance or other performance characteristics. These depend on the formulation, firing process, and resulting microstructure.
We must also distinguish between the body and the exposed top surface. In glazed porcelain tiles, the glaze, texture, and finish largely determine surface characteristics such as stain resistance, slip resistance, and wear. In unglazed full-body porcelain tiles, these characteristics depend directly on the composition, microstructure, and the finish treatment given to the tile body itself.
Both types can achieve comparable performance, but this must be established through appropriate testing. Glazed tiles are evaluated for surface abrasion using the applicable glazed-tile test, while unglazed tiles are evaluated using the deep abrasion test. These methods measure different forms of wear and are not directly interchangeable.
The key point is that body colour alone does not establish a tile’s technical performance. The key is to assess the complete tile against the requirements of its intended application. Neither the body colour nor the product category alone guarantees desired performance in specific application and usage environment.
[IN]: What is your advice to architects and interior designers when specifying ceramic tiles?
DV: My advice is to pay attention to the Technical Data Sheet (TDS) and the applicable product standards. Examine the declared characteristics, test methods, and performance claims carefully. Most importantly, ask for data relating to the specific tile you have selected.
The catch is that in a company brochure, a product category or series may contain tiles with different thicknesses, finishes, glazes, and manufacturing processes. For example, you may see ‘GVT 600 mm x 1200 mm Collection’ of a brand which may show multiple finishes supporting different aesthetics. Never assume that all their technical characteristics are identical.
Before finalising your selection, ask these questions:
- Water Absorption and Strength:
What is the water absorption, and what are the modulus of rupture (MOR) and breaking strength of this particular tile? - Thickness and Breaking Strength:
What is the actual thickness, and does the tile’s breaking strength meet the requirements of its intended application? - Wear Resistance:
If it is a glazed tile, what is its PEI abrasion rating? Confirm the rating for the exact SKU, not just the collection. - Slip Resistance:
What is the available slip-resistance test result? Depending on the application, this may include the R-rating under the German DIN 51130 ramp test or the Pendulum Test Value (PTV). Understand the test method and its relevance to the actual site conditions. - Stain Resistance and Cleanability:
How easily can the surface be cleaned after spills and exposure to common contaminants? This is particularly important for flooring. Some highly textured or aesthetically enhanced surfaces may be suitable for walls but can become difficult to maintain when used on floors.
Remember, Tile Body colour is not a deciding factor in these performance assessments.
My advice is to consider both – the brand’s reputation for technical reliability, and the specifications and test certificates of the specific tile selected. A trusted brand provides confidence; tile-specific data confirms its suitability for the intended application⊗
DINESH VYAS is a building materials professional with nearly three decades of experience in business strategy, product development, and market development. As part of the senior leadership at Prism Johnson Ltd., he drives strategic initiatives for the H & R Johnson division, focusing on business strategy, product development, and customer education. His career includes associations with Ambuja Cement, Larsen & Toubro, and Shell. He holds an M Tech in Applied Geology and an MBA in Marketing.
Passionate about advancing knowledge in the building materials industry, he works to educate architects, interior designers, construction professionals, students, and consumers on materials, their applications, and technical performance.
He is the author of ‘Modern Ceramic Tiles: A Handbook for Professionals’ and shares his knowledge through the Dinesh Vyas – OTF YouTube channel, dedicated to industry insights and professional and consumer education.
