BRICK ISSUE GUIDANCE :
MANGANESE STAINING IN BRICKWORK
SYMPTONS, PREVENTION, CURE.
A brown or greyish staining that streaks down the face of the brickwork from the mortar joint is often magnesium staining.
Manganese oxide is a typical colouring agent in facing brick or mortar. During production these manganese agents undergo several chemical changes which can result in manganese compounds that are soluble in water and have varying levels of solubility in weak acids. The sulfate and chloride salts of manganese may migrate through to the face of the brickwork. When they reach the mortar joints the salts are neutralised by the cement or lime present in the mortar and then may produce insoluble manganese hydroxide on the mortar joint. |
This may streak down the face of the adjoining brickwork and when dry converts to brown manganese tetroxide and leaves the typical brown staining.
The process can occur simply due to the reaction of the manufactures use of Manganese Oxide through this process with atmospheric acids (acid rain). It can also be encouraged by incorrect or inappropriate brick acid cleaning. |