Crazing in Glazed Porcelain and Ceramic Floor and Wall Tile

Cracks are starting to appear on my floor tiles

Overtime and in very rare circumstances floor tiles and wall tiles can have small hairline cracks appear in the glazed surface of a porcelain or ceramic tile. In the tiling industry, this is referred to as 'crazing'. 

Crazing is an inherent characteristic of glazed porcelain and ceramic tiles and can occur over time naturally. Sometimes crazing is a sped up by tile manufactures as a design feature to create a more hand made or crackled glass appearance. 

It is important to note that crazing is not a defect of a porcelain or ceramic floor or wall tiles but recognised as an inherent property that can occur on all types of ceramic and porcelain glazed tiles. ​​

Are cracks a problem?

Floor tiles and wall tiles that have crazing occurring on its glaze will perform in the same way as without the hairline cracks. Similarly to how small hairline cracks appear in pottery and other glazed goods, porcelain and ceramic tiles can have the same phenomena occur. 

Why are the cracks appearing?

The glaze of ceramic and porcelain tiles is made of micron thick glass. During the manufacturing process, the glaze and the body of the porcelain and ceramic tile are bonded together using extreme heat in a kiln. These two materials can expand and contract at different rates naturally and this is what causes the hairline cracks known as crazing. 

The most common reasons for floor or wall tiles to craze is:

• Extreme fluctuations in temperature.
• Continuous movement of a substrate or structural wall.
• Some reports indicate that if a extremely high bond adhesive is used, the setting of the adhesive can cause the tile to slightly bend and then result in crazing of the glaze.

However the most common reason is that crazing is an inherent property of ceramic and porcelain tiles. Crazing just happens and it cannot be explained. However please note that it is not detrimental to the performance of your tile. 

How can I fix the cracked tiles?

Please note that crazing of glazed porcelain and ceramic tiles does not affect the performance of the tile. Normally crazing is just ignored. However if the crazing is significant or personally annoying then the only way to resolve the issue is to replace the tiles. Crazing cannot be fixed using any tile repair solutions as the surface is not cracked.

As crazing is an inherent characteristic of glazed porcelain and ceramic tiles, this means that the cost to replace tiles with crazing cannot be the fault of anyone and cannot be charged back to anyone in particular. 

What if the crack is not crazing?

If the tile is not crazing and had a crack in it then there are tile repair solutions available to hide and improve the appearance of the tile. 

Cracked tiles are different to crazing because cracks are not inherent characteristics of porcelain or ceramic tiles with a glaze. Cracks often make their appearance known because they are substantially larger in appearance than crazing and are created by an external force. 

The most common reason for cracked tiles is improper application of adhesive, dropping heavy objects or significant movement in the substrate or structural wall. 

To hide and improve the appearance of cracked tiles consider this product. 

Relevant ISO Tests

• Resistance to Thermal Shock ISO 10545-9
• Frost Resistance ISO 10545-12
• Resistance to Crazing (Glazed Tiles) ISO 10545-11