Moisture Measurement
The precise quantification of fiber blends by weight relies on establishing a reliable starting point for dry material mass. A technique called thermal desiccation weight loss measures the moisture content of a textile specimen by heating it to evaporate all absorbed water. This step is critical because natural fibers like cotton and wool absorb significant atmospheric moisture, which would otherwise distort the calculated dry weight of the blend.
It is the initial procedure in quantitative fiber analysis.
Heating Cycle
The test procedure requires placing the specimen in a ventilated oven held at a constant temperature of one hundred and five degrees Celsius. The sample is heated until it reaches a constant mass, which indicates that all free water has been evaporated. This heating is done in successive cycles, with each weight measurement performed after cooling the sample in a desiccator.
The difference between the initial mass and the final dry mass is the moisture content.
Fiber Compensation
Once the dry mass of the specimen is established, the subsequent chemical dissolution steps can be executed with high accuracy. This dry weight is also used to calculate the moisture regain of the fiber, which is then added back using standardized commercial regain allowances. This step ensures that the commercial weight of the yarn is reported correctly, which is necessary for trade transactions.
This standardizes the reported composition across different ambient testing conditions.
Analytical Limit
This method is designed to remove absorbed water. It does not affect chemically bound water or degrade fiber structures. Volatile finishes can interfere with the results, limiting the test’s use on heavily lubricated yarns.
