DISTORTION Any marked distortion of the casting is probably related to a distortion of the wax pattern. This type of distortion can be minimized or prevented by proper manipulation of the wax and handling of the pattern. Unquestionably some distortion of the wax pattern occurs as the investment hardens around it. The setting and hygroscopic expansions of the investment may produce a non-uniform expansion of the walls of the pattern. This type of distortion occurs in part from the nonuniform outward movement of the proximal walls. The gingival margins are forced apart by the mold expansion, whereas the solid occlusal bar of wax resists expansion during the early stages of setting. The configuration of the pattern, the type of wax, and the thickness influence the distortion that occurs. For example, distortion increases as the thickness of the pattern decreases. As would be expected, the lower is the setting expansion of the investment, the less lower is distortion.  Philips’ Dental Material, pg- 223