3f2c04aa_ick___Cleaning___Stain_Removal__Description
[Stain] Manganese Stains [Cause] The stain occurs most characteristically along the edges of the brick and is generally caused by excessive water penetration. In severe cases it may show as a stain across the face of the brick. [Removal] The problem with manganese staining is not so much the removal of the stain, as preventing its return in a short period by certain methods during construction. If it does occur, Phosphoric acid or Acetic acid can be used. [Description] 
A dark-blue brown discolouration may occur on bricks that have been coloured grey or brown by the addition of manganese during manufacture.
Brick | Cleaning | Stain Removal
Description