Spectral Sensing
Non-destructive spectral analysis positioned on sorting conveyors separates post-consumer textiles based on polymer composition. Recycling facilities and specialized inspection lines deploy SWIR imaging to capture short-wave infrared light absorption signatures across running fabric webs. Infrared wavelengths between 1000 nanometers and 1700 nanometers penetrate surface dyes to interact with core molecular bonds.
Indium gallium arsenide camera sensors record spatial and spectral data simultaneously to construct high contrast material maps.
Chemical Identification
Different fiber polymers exhibit unique chemical absorption bands within the short-wave infrared spectrum. Polyester exhibits distinct overtone bands corresponding to ester carbonyl groups, while cotton displays strong hydroxyl absorption peaks. Algorithms analyze pixel spectra against reference libraries to distinguish cotton from polyester, nylon, or acrylic blends.
Dyes that mask visual color differences remain transparent under short-wave infrared wavelengths, enabling accurate fiber identification regardless of fabric color.
Moisture Detection
Water molecules absorb short-wave infrared radiation intensely around 1450 nanometers. Hyperspectral cameras detect localized moisture variations across fabric widths during tentering or drying stages. Regions with elevated moisture content appear dark on infrared intensity maps, signaling uneven drying performance or padder nip pressure variations.
Sorting Automation
High speed optical sorters utilize spectral classification maps to trigger automated air jets that divert fabric garments into dedicated material bins. This automated separation achieves high purity levels required for chemical fiber-to-fiber recycling processes.
