Lab Dip Approval against Bulk Shade under Three Illuminants
Tri-illuminant shade approval aligns lab dips with bulk by enforcing primary D65 visual matching alongside secondary TL84 and Illuminant A metameric tolerances.
Continuous Pad Dry Steam
Process Sequence
Wet processing machinery applies dye liquor to woven cotton fabric by padding, drying, and steaming in an uninterrupted production sequence. Utilizing continuous pad dry steam enables high-speed color application on long yardage orders without shade variation along the roll length. The fabric passes through pad rolls at controlled squeeze pressures before entering a pre-dryer to lock dye particles into place.
Immediate saturated steam exposure hydrolyzes reactive dyes to form covalent bonds with cellulose molecules.
Chemical Fixation
Sodium carbonate and urea in the pad bath stabilize reactive dyes during high-speed dwell periods. In continuous pad dry steam applications, precise chemical concentrations prevent premature dye hydrolysis before steaming. Uniform liquor pick-up guarantees even shade depth across fabric widths up to two meters wide.
Squeegee roll pressure adjustments balance left-to-right shade uniformity during initial impregnation.
Thermal Control
Saturated steam chambers maintain temperature levels at one hundred two degrees Celsius to expand cotton fibres. Moisture condensation during steaming transfers thermal energy into wet fabric, accelerating dye diffusion into fibre cores. Air leaks into steam chambers cause shade dulling and uneven fixation due to localized oxidation.
Operational Boundary
Blended synthetic fabrics require alternative thermofixation steps because polyester fibres fail to absorb reactive dyes under atmospheric steam. Heavyweight canvas constructions risk migration defects if infrared drying speeds exceed moisture evaporation capacities.