What is the proper way to repoint brick?

Under no circumstances should you allow a contractor to apply a thin coat of portland cement mortar over the top of existing joints. The repair will be short lived for several reasons. The mortar itself will be brittle and subject to cracking. The new mortar will adhere poorly to the old, unsound mortar. Finally, mortars high in portland cement content may damage older, soft brick by driving moisture away from the joint and into the brick. This excess moisture will eventually lead to deterioration of the brick or spalling of the brick face through the freeze/ thaw cycle.

Correct pointing requires removal of old mortar to a depth of 2½ times the joint width. This allows the mortar to adhere to the sides of the brick, not to the old mortar.

Mortar composition must be compatible to the hardness of the brick. Older brick require higher lime content mortar so the rates of water vapor transmission of the mortar and brick are similar.