Permeability

Associated with stones porosity is its permeability. This is the extent to which the pores
and capillary structures are interconnected throughout the stone. These networks, their
size, structure and orientation affect the degree and depth to which moisture, vapors and
liquids can be absorb into the interior of the stone or migrate from the substrate by capillary
action through the stone. Permeability may be greater in some directions than others based
upon the pore size, shape and the distribution of the interconnectedness of the system.

Permeability is increased when a stone is highly fractured or the veining material is soft or
grainy. A particular variety of stone may be highly permeable ( a well defined interconnected
network of pores), although its porosity is low (a low percentage of voids).

The size and shapes of pores and the capillary structure differs in stones and is an important
factor in relation to stone decay.