For the single and large casts, sometimes weighing several tons, suitable models of cutting boards foam heated nichrome wire, which, for example, the templates out of cardboard "like clockwork" cut block foam. The model then obtained by casting it to have high accuracy (respectively, lower metal) and the competitive presentation. Freely can be seen, "feel" cast back in the model, Gaugeable its walls, which under normal molding "in flasks in the land" for the complex with several rods cast just did not do it. Professor of Internet Governance is likely to agree. There is no displacement of the cores and molds in the assembly (because you do not do bars), which increases the dimensional accuracy of castings to the 7 – 9th grade to GOST 26645-85, and the roughness of the surface to 12.5 … 25.0 mm. Color model fast drying paint with refractory antipenetration powder (usually obtained coating thickness of 0.4 – 0.8 mm), collected from the sprue, poured dry sand in a box (container) and pour the metal. When you fill a metal vaporizes the model and is it replaces.
In this operation, replace the one on the other – the whole "trick" or know-how technology of casting on gasified models (LGM), which defines the name of the terminology used in the foundry and makes it unique. In all other ways of forming the model there is a preliminary operation to remove it before pouring, and in the absence of such a removal model of the form lies the 'secret' accuracy of the castings. That zaformovali, then poured in a stationary surrounding sand.