The relationship of pattern position to the flow of gold and casting completeness.

To minimize the possibility of incomplete casting due to improper pattern orientation relative to the sprue and direction of the casting arm motion, the following precautions should be taken. 1. Locate the pattern in the trailing half of the casting ring 90 to 135 degrees away from the sprue position. 2. Once the pattern is in the position described, locate it downward in the lower outer quarter of the trailing half of the casting ring and secure it in that position. 3. Mark the ring or sprue former so that the invested pattern can be oriented properly in the casting arm. 4. When using an electric casting machine, be certain that the pyrometer is correct. If in doubt, it is advisable to check the melt state of the gold before casting.