This method allows precise depths of mortar to be removed. It is the slowest method of the three, but will damage the least number of masonry units. Rotary power grinders . If the removal task is large, then use of power tools is a consideration. The use of impact chippers and saws or grinders will speed the chore, but can lead to breaking of bricks or overcutting of joints, potentially cutting into adjacent masonry units.
Rotary saws grind the mortar from the joints.
The width of the saw blade should be smaller than the width of the joint itself to eliminate any damage to the masonry unit. However, this technique leaves a thin layer of mortar attached to the masonry that may be weak and will not provide a good bed for the repointing mortar. Another problem associated with rotary cutters or grinders is that the grinding wheel will not be able to clear the extreme ends of head joints without sawing into the brick above or below the joint being prepared. This means that the head joints will have to be finished by hand anyway to provide a properly prepared joint bed. Power chisels .