Standard Specification
Aqueous extraction procedures govern ISO 105 Z11 when textile laboratories evaluate water soluble colorants inside dyed or printed cellulose and wool fabrics. Technicians subject prepared fabric samples to a specific volume of distilled water at a controlled temperature for a defined duration before separating the liquid phase. Spectrophotometric measurement of the extracted liquor reveals the concentration of displaced dye molecules released from the fibre matrix during the extraction interval.
This numerical result establishes the bleeding propensity of the substrate under wet conditions during subsequent garment assembly or domestic washing. The boundary of applicability applies strictly to colorants that dissolve in water rather than pigments held by binder resins on the fabric surface.
Extraction Parameter
Water temperature dictates the kinetic energy driving dye molecules from the interior of the yarn into the surrounding aqueous medium during the test cycle. Operators maintain strict thermal control because minor fluctuations alter the solubility coefficient of reactive and direct dyes residing within the amorphous regions of the polymer chain. Immersion duration operates as the secondary control variable determining whether the transfer of colorant reaches equilibrium or remains bounded by diffusion rates.
Agitation speed inside the extraction vessel prevents concentration gradients from forming near the fabric face during the prescribed time window. Mill technicians calibrate these variables against reference substrates to eliminate systematic bias before recording absorbance values on the spectrophotometer.
Absorption Measurement
Filtrate separation removes suspended particulate matter that might otherwise scatter light and distort the spectrophotometric reading taken from the aqueous extract. Optical cells receive the cleared liquid and record maximum absorption peaks corresponding to the characteristic wavelength of the applied dye class. Dilution protocols apply automatically when concentrated extracts exceed the linear response range of the analytical instrument.
Calibration curves derived from known concentrations translate raw optical density figures into milligrams of released colorant per gram of dry textile material.
Commercial Tolerance
Purchasing agreements between apparel brands and manufacturing facilities specify maximum allowable absorbance thresholds derived from this standard before bulk shipments clear final inspection. Exceeding the agreed threshold triggers rejection at the port of entry or manufacturing floor because substandard wet fastness leads to staining of adjacent fabrics during household laundering. Mills adjust dye selection and fixation chemistry on the production line when pre-shipment extraction tests signal potential failure against the commercial threshold.
Retail performance ultimately depends on maintaining extractable colorant levels below the limit defined by the specification.
