Wet Processing & Colour

Colour and function. Diffusion theory behind dyeing, pretreatment, dyeing, printing, finishing, drying and effluent management.

• Diffusion — Diffusion is the movement of molecules from high to low concentration. Learn Fick's law, diffusivities in gases, liquids and solids, steady diffusion through films, mass-transfer coefficients and dimensionless numbers (Sc, Sh), and how diffusion limits separation and reaction rates.
• Wet Processing: Pretreatment, Dyeing, Printing & Finishing — Adding colour and function. Learn pretreatment (singeing, desizing, scouring, bleaching, mercerisation), dye classes and fibre matching (reactive, vat, disperse, acid, basic), dyeing theory (exhaustion, fixation, diffusion, liquor ratio), recipe calculation, batch and continuous dyeing machines, printing (screen, rotary, digital), finishing (mechanical and chemical — softening, easy-care, water repellency, flame retardancy), and effluent treatment and water saving (ZLD) — with Python for dye recipes, chemical quantities and water use.
• Drying — Drying removes moisture from solids by evaporation. Learn moisture content (wet and dry basis), equilibrium and critical moisture, constant-rate and falling-rate periods, drying-time calculations, heat requirements, and dryer types (tray, rotary, spray, fluid-bed, freeze).