kattilakiven

Kattilakivi is a Finnish term that translates to "boiler stone" or "furnace stone." It refers to a type of stone or rock used historically in the construction of wood-fired stoves and ovens, particularly in Finland and other Nordic countries. These stones were chosen for their ability to withstand high temperatures, retain heat, and release it slowly, contributing to efficient and consistent heating.

The specific types of rock used for kattilakivi varied depending on local availability and geological composition. Common materials included soapstone (tuhkakivi), granite, and certain types of sandstone. Soapstone was particularly favored due to its excellent heat retention properties and its relative softness, making it easier to shape and work with. The stones were often carefully selected and sometimes shaped to fit precisely within the firebox or oven cavity.

The primary function of kattilakivi was to absorb the intense heat generated by the burning wood and then radiate it into the surrounding space or cooking area over an extended period. This allowed for prolonged warmth even after the fire had died down, making it an efficient way to heat homes and cook food. In traditional Finnish homes, the masonry heater, often built with large amounts of brick and incorporating kattilakivi, was a central feature for both heating and cooking. The term can also refer to the specific heat-retaining stones used in modern saunas for heating the water.