What role does mortar play in the development of efflorescence?

Mortar plays a significant role in the development of efflorescence due to its composition, which can contain various soluble salts. When moisture penetrates a masonry wall, it can dissolve these soluble salts present in the mortar. As the moisture moves through the wall and eventually evaporates at the surface, it leaves behind these salts, which crystallize and form the white, powdery deposits recognized as efflorescence.

The presence of soluble salts in the mortar is a primary factor contributing to this phenomenon, making it essential to understand how the materials used in masonry work together. While other factors, such as the availability of moisture and environmental conditions, also influence efflorescence, the role of mortar as a source of these soluble salts is particularly critical in its development.