This Diamond Grinder Blade made by Bon Tool, will have those joints prepared for new mortar in no time! We recommend this 4″x.08″ diamond blade to center cut joints. Use on a right angle grinder. Arbor size 5/8″x7/8″. Use wet or dry. After joint is center cut, use a plugging chisel, awl, or 6 in 1 Tool, to finish removing the mortar without damaging the brick. Grinder marks on bricks are not only unsightly, but they damage the faces of the brick, exposing them to rapid decay.