Next, mix up a slightly larger batch of epoxy sealer and apply it to the entire crack using a 1 ½-in.-wide putty knife or margin trowel. Spread the sealer about 1/8 in. thick and 1 in. on either side of the crack. Also, cover the entire flange of each injection port with crack sealer, leaving only the extended neck portion showing. Smooth out the sealer and feather its edges with a paintbrush dipped in mineral spirits.