Success depends on grafter skill, quality of scion wood, age of trees, and care after grafting.
Without proper care, grafts may fail to grow or may grow poorly. However, the seal shrinks upon drying, producing cracks, and recoating the cracked and shrunken areas is necessary to reestablish a good seal. Recoating is generally done 1 or 2 days after the initial application. Black emulsions absorb a tremendous amount of heat, sometimes enough to kill the cambium cells that are responsible for the healing process. Use less water to prepare a thicker solution that will last longer and offer greater protection from insects such as flatheaded borers.