Which is NOT a consideration when selecting replacement mortar for historic brickwork?

• A. Color
• B. Hardness
• C. Porosity
• D. Vapor permeability

Answer: (A)

When choosing replacement mortar for historic brickwork, the focus is on how the mortar performs with moisture and with the surrounding bricks over time. Hardness is important because the mortar should wear at a similar rate to the bricks and not be so hard that it damages brick faces or so soft that it erodes quickly. Porosity matters because it determines how much water the joint can absorb and how it dries, which affects freeze–thaw durability and salt movement. Vapor permeability is essential so moisture can move through the wall rather than being trapped, which helps prevent issues like efflorescence and spalling.

Color, while it affects appearance, does not influence these important performance characteristics. It can be addressed after the mortar’s functional properties are ensured, through tinting or finishing, if needed. So color is not a consideration for selecting the mortar from a compatibility standpoint.