In the production of Meehanite flake graphite castings, the composition of the iron, whilst important, is only a part of the process for achieving a definite metal structure. The more important factor is mass, ie wall section thickness, and its effect on cooling rates. For normal cast iron, slow cooling (as in thick sections) produces a coarse open-grained, low strength structure, whereas fast cooling (as in thin sections) results in a hard, brittle, unmachinable structure. Thus in Meehanite practice, the structure of the metal and properties required are related to the section thickness of the casting.