Questions have arisen recently on the Histonet listserver about the properties of zinc formalin fixative. The advantage of zinc formalin over the usual formalin fixatives appears to be that zinc ions hold macromolecules in their native conformation via coordinate bonds, preventing the damaging crosslinkages that formaldehyde alone would create. The result is greatly enhanced immunopreservation: rarely is antigen retrieval necessary, and primary antibodies can be diluted 2 to 10 fold greater than usual.