Cracked eggs should not be incubated because they cannot retain the needed moisture and because that portion of the eggshell will not have the permeability needed for the developing embryo. Eggs with a section of the shell that is not permeable will often produce deformed keets.

Tiny or thin cracks, especially ones that occur later during incubation, may be repaired with water-soluble white glue or melted candle wax. Monitor the egg carefully to be sure it does not go bad. If the crack is not tiny, it is best not to continue the incubation.