Some historic mortars, particularly in the late 19th century,
were tinted to match or contrast with the brick or stone. Red
pigments, sometimes in the form of brick dust, as well as brown,
and black pigments were commonly used.
Modern pigments are available which can be added to the mortar
at the job site, but they should not exceed 10 per cent by weight
of the portland cement in the mix, and carbon black should be
limited to 2 per cent.
Only synthetic mineral oxides, which are alkali-proof
and sun- fast, should be used to prevent bleaching and fading.