Thermal Stress Fracture

Thermal stress fracture is a crack or break caused by uneven expansion or contraction when a material experiences a rapid or significant temperature change. It can occur in glass, ceramic, stoneware and other brittle materials, as well as in some baked products where temperature gradients create internal stress. The term is also related to thermal shock.

Thermal stress in kitchen equipment

Glass and ceramic equipment can crack when one area heats or cools much faster than another. For example, placing a cold glass dish into a hot oven or pouring boiling liquid into a chilled glass vessel may create stress that exceeds the material’s tolerance. Only use equipment rated for the intended temperature range and follow the manufacturer’s instructions.

Thermal stress in baked goods

Some baked products, especially custards and cheesecakes, can crack when the surface and interior cool at different rates or when the structure is overbaked and contracts. Rapid cooling can contribute, but cracking may also result from excessive baking, over-aeration, formulation or pan preparation. Pastry shells may crack if handled while hot or subjected to sudden temperature changes.

Example: a cheesecake may develop surface cracks as it cools if it is overbaked or experiences a rapid temperature change. A glass baking dish may fracture if moved abruptly from a hot oven onto a cold or wet surface.

Prevention

• Use glass and ceramic cookware only within the manufacturer’s temperature limits.
• Avoid sudden changes between hot and cold surfaces or liquids.
• Allow baked custards and cheesecakes to cool in a controlled manner according to the recipe.
• Use appropriate oven temperature and avoid overbaking.
• Inspect equipment for chips, scratches or existing cracks before use.

Chef’s safety note: discard food if glass or ceramic fragments may have entered it. Never use cracked equipment for food preparation or service.