The EMS Domino rack is "U" shaped and made from an aircraft alloy sheet stock with serial perforations; thermally bonded spaceage copolymer; 5 mm diameter holes, 28 holes per rack. The formvar film cast on the rack will stretch across a series of smooth edged holes forming a flat, wrinkle free film that is ready for grid mounting. The Domino Rack allows the sections within the slot to dry flat and wrinkle free; it reduces the film and section contamination to negligible levels.
Moran, D.T., and Rowley, J.C., (1987). "Biological Specimen Preparation for Correlative Light and Electron Microscopy in Biology: Microscopy and Methods, ed. M.A. Hayat. Academic Press, New York./ pg 1-22.