Once these conditions are met, the sap will begin to flow. When the collecting tank is full, the sap is transferred to another tank on a truck or other vehicle and taken to the sugar house. The evaporator pan has a maze of partitions that lead the sap back and forth over the fire below while it gradually becomes hotter and hotter. Eventually, the thickened liquid works its way into the final section. Here it continues to boil until testing shows that it is the right consistency.
More modern methods give more accurate results.
When a batch of syrup is ready, it is drawn off through a faucet into storage containers. If conditions are at their best, the flow of sap will be so fast that the boiling has to continue well into the night. The evaporator and other equipment in the sugar house must be washed and put away. In the sugar bush, the tubing must be washed in place.