Mathematical Adjustment
Adjustments to the bone dry weight of a residue account for the unintended partial solubility of a fibre when it is exposed to a chemical reagent. Mass loss correction factors, often designated as d-factors, ensure that the final calculation reflects the actual composition of the yarn rather than a value distorted by the testing process. These coefficients vary depending on the temperature and immersion time specified in the test method.
Reagent Solubility
Polyester and cotton blends often require the use of sulfuric acid or boiling sodium hydroxide. While the acid targets the cellulose, a mass loss correction accounts for the slight degradation of the polyester surface. Labs establish these values by running blank tests on pure samples of the insoluble fibre.
Weight Precision
Precision improves when the correction is applied to the final bone dry weight of the residue. If the mass loss correction is omitted, the percentage of the dissolved fibre appears higher than reality. This leads to commercial disputes over fabric specifications.
Standard Compliance
Reference tables in ISO 1833 provide the standard values used by most commercial inspection bodies. When a specific mill uses a proprietary finishing process, the mass loss correction might need local validation. This prevents the finish from being mistaken for a loss in fibre mass.
