Kalkspatz

Lime sparrow in a vessel wall with a small crack on the vessel surface

Kalkspatz is a defect that occurs in ceramics and is caused by a small piece of lime in the mass after firing .

The lime turns into hygroscopic burnt lime through the firing process of the ceramic . After it burns, this absorbs water from the environment, which increases its volume. He breaks out a piece of the fired ceramic and can be recognized as a white chunk. This error often occurs with bricks .

Sufficient pressure is only generated to break open the ceramic when water is absorbed slowly. This can take months for dense ceramics that absorb very little moisture. With fast conversion, if z. B. a porous brick is immersed in water, a slaked lime sludge is created instead and the ceramic does not break open.

This dipping is very reluctant to use bricks because it causes unnecessary material and transport costs and affects processing on the construction site. But anyone who received very damp bricks can assume that the brickworks has serious problems with lime sparrows.