Quantifying Carding Waste Composition Drift in Cotton Synthetic Blends
Carding waste selectively extracts short cotton over synthetic staple, shifting sliver ratios by up to 2 percent synthetic enrichment unless compensated in laydown.
Gravimetric Composition Testing
Analytical Methodology
Quantitative analysis of fibre blends through selective chemical dissolution relies on precise mass measurements before and after chemical treatment. This method, known as gravimetric composition testing, is the primary technique used to verify fibre content claims in commercial textiles. It works by exploiting the differing solubilities of natural and synthetic polymers.
The procedure yields highly accurate results for binary and ternary blends.
Laboratory Procedure
Analysts begin by drying the textile specimen in a conditioned oven to establish a baseline mass. After exposure to a specific solvent that dissolves one fibre type, the remaining material is collected, washed, dried and weighed. Comparing the dry weights before and after dissolution allows the technician to calculate the percentage of each fibre in the blend.
Gravimetric composition testing requires precise analytical balances that measure to the nearest milligram.
Solvent Selection
Different fibre combinations require specific chemical agents to ensure that only the targeted fibre dissolves while the others remain completely undamaged. For example, a mixture of acetate and cotton is treated with acetone, which dissolves the acetate without affecting the cellulose. When performing gravimetric composition testing on polyester and wool blends, a boiling sodium hydroxide solution is used to dissolve the wool.
If the wrong solvent is chosen, both fibres may partially dissolve, which invalidates the test results and leads to incorrect composition reports. These chemical protocols are strictly standardized by organizations like ISO and ASTM.
Industrial Application
Garment importers rely on these test reports to comply with customs regulations and labelling laws. Correct composition data ensures accurate duty rates and prevents costly customs delays at international ports.