Manufacturing Process

• Ceramic tile is made out of clay that is separated out into tile shapes and then heated in an oven or fired in a kiln. The intense heat cures the tiles and hardens them into their permanent shape. After the tiles have been fired, they are resistant to most forms of heat, and the glazes used on them tend to protect the tile even further.
  
  

Indoor Heat

• Inside the house, there are not many sources of heat that pose any danger to ceramic tiles at all. However, the tiles do tend to breathe, and tiles near heat sources such as vents will undergo microscopic expansion and retraction from the changes between hot and cold air. This can sometimes loosen the tiles or cause them to develop small cracks, but it is rarely a problem.
  
  

Outdoor Heat

• Outside, frost is much more dangerous to tiles than heat. Even in the hottest desert climates, ceramic tiles can resist high temperatures very well, although they will undergo the same breathing condition that indoor tiles experience. Outdoor ceramic tiles are unglazed, since the glazes can be too easily damaged by outdoor conditions, and this can lower the tiles' protection against other factors beside heat.
  
  

Glazes

• Ceramic tile glazes serve two purposes: first, they protect the tiles against accidental scratches and other types of damage, and second, they add to the appearance of the tile. Some glazes add a sheen to the tile to make it shine, while other types give the tile a certain texture. These glazes provide some protection against direct heat.
  
  

Countertops

• Ceramic tiles are not invulnerable to high heat, and they can be scorched, burned or cracked. This typically occurs with ceramic countertops, where cooking projects can lead to very hot objects accidentally touching the tile. A hot skillet or pan can cause tile damage, heating sections until the tile cracks and the glaze is melted or burned.