Moisture Analysis
Laboratory drying procedures define the specific conditions needed to remove water from cellulose samples. Adherence to iso 638 solids drying provides a standardized way to account for the water weight in a shipment, which is necessary for commercial transactions. The sample is heated to 105 degrees Celsius until its mass reaches a constant state.
Calculation Accuracy
The difference between the initial weight and the final dry weight represents the moisture that was evaporated during the process. In the context of iso 638 solids drying, the result is used to adjust the total tonnage of a delivery to an air-dry basis. This ensures that the buyer is only paying for the fibre and mineral content rather than the water.
Precautions must be taken to prevent the sample from losing volatile organic compounds other than water.
Process Control
Accurate moisture data is required to calibrate on-line sensors that monitor the web in real time during production. Following iso 638 solids drying allows the laboratory to verify that the machine is running within its specified operating window. Variations in solids content can affect the way coatings are absorbed and the way the board curls.
This standard is a fundamental tool for quality assurance in both pulp mills and converting plants. Reliability in these tests ensures fair trade between suppliers and converters.
