The load is placed in the oven where it is heated for 2 hours arising to 70 ºC. Then the mould is taken from the oven and placed in a pit for the molding of the final cores. Mould is brushed and formed. The whole process takes from 2 to 4 more hours, depending on the size of the mould. When this procedure is completed the mould is returned to the furnace. The temperature of the mould in this moment drops to approx.20ºC.
Following the mould is heated up to 120ºC during at least 3 hours. The mould is taken again out of the furnace to coat the final core from 3 to 5 times depending on the quality of the cylinder. Coating takes from thirty minutes to one hour, during this time the temperature falls about 10ºC.
After this, the mould is loaded again into the furnace turned by 180º around the horizontal axis and in this position is heated to 220ºC during 3 more hours. After this preheating process the mould remains for one hour with the furnace switched off and closed in order to achieve the equalization of the temperature throughout the mould.