Crazing consists of rupture of the glaze in the form of hairline cracks that develop randomly on the glazed surface. This defect occurs because the glaze is subjected to tension, either at the kiln exit (immediate crazing) or after the tile installation (delayed crazing). … All first-quality tiles must pass the test.

What causes tile crazing?

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 contact at different rates naturally and this is what causes the hairline cracks known as crazing.

What does crazing look like?

What is Crazing? Have you ever seen a piece of pottery where the surface looks like it’s covered with a spider web of tiny cracks? That’s called crazing. They are not cracks in the actual piece of pottery but rather surface-level cracks in the fired glazed of the piece.