Patching requires preparing the repair zone by saw cutting the edges and a minimum of 3/4" deep. Injection Grout fills voids and does not require the same level of preparation.
Injection Grout does not need special equipment for successful application. Common devices are basters, syringes, and ketchup squeeze bottles.
Drill a series of injection ports directly into the center of the crack at a downward angle. Seal the surface of the crack with non-staining easy to remove clay. Begin by injecting the lowest port and work upwards.