Colour approval belongs to a fabric and process combination

A digital print file contains pixel values, not textile colour. The physical appearance of a printed motif emerges from the interaction between deposited colourants, auxiliary chemicals and the structure of the receiving cloth. In digital textile printing, ink chemistry must match the fibre class: reactive inks require cellulosic fibres with subsequent steaming and washing, disperse sublimation routes require compatible synthetic polymers, and pigment systems rely on a binder and dry heat fixation across cotton and blended substrates.[S01] Within a single fibre category, rotary and digital printing studies confirm that yarn twist, weave or knit tightness, surface hairiness and prior wet processing alter drop spread, penetration depth and perceived shade depth.[S02]

A local apparel producer cannot treat unprinted white or dyed cloth as a uniform commodity. Two cotton jersey lots that look similar on a rack may carry different spinning oils, optical brighteners, residual alkalinity, mercerisation levels or mechanical finishes. When an aqueous inkjet drop strikes those surfaces, differences in wetting tension and capillary wicking change both fine-line dot gain and solid-area reflectance.[S01][S02] If the factory does not record which fabric lot received the approved print trial, a later batch printed with the same file and machine settings can shift noticeably in hue, saturation or edge definition.

GFT proposes that every substrate entering a print-on-demand or short-run service carry a versioned material passport before colour profiling or customer sampling begins. The passport is an operational control record within the factory performance-management system rather than a marketing certificate, binding the physical roll or blank batch to the parameters governing colour reproduction and dimensional stability.[S12][S15]

• Supplier and lot identity: Record mill or blank distributor, article code, delivery date, batch or dye-lot identifier and roll or carton numbers.[S21]
• Verified fibre composition: State declared fibre percentages and require supplier test documentation where pure cotton or a blend is specified.[S01][S02]
• Construction and areal mass: Document weave or knit structure, yarn count, gauge, width and mass per area, governing ink penetration and pretreatment pick-up.[S01]
• Preparation and surface finish: Identify bleaching, optical brighteners, dyeing, singeing, mercerisation, enzyme washing or softeners that resist pretreatment and binder adhesion.[S01][S30]
• Base shade and whiteness baseline: Retain an unprinted cutting and record its visual or instrumental baseline under agreed viewing conditions to detect lot drift.[S14][S21]
• Thermal and care shrinkage: Record length and width change after curing and intended washing and drying, referencing ISO 3759:2011 and ISO 6330:2021 scopes.[S12][S27]

Keeping these records attached to the fabric lot prevents blaming the printer or operator for a shade shift caused by an unannounced blank substitution. When a service decorates imported T-shirt blanks via direct-to-garment (DTG) or direct-to-film (DTF) routes, the blank manufacturer controls spinning, knitting, scouring and garment dyeing upstream.[S15][S30] Mixing cartons from different upstream production runs alters liquid pretreatment pick-up and heat-press scorching behaviour within the same size run, so mixed lots must be segregated at goods receipt and assigned distinct lot identifiers before prepress release.[S15][S17]

For roll-to-roll cut-and-sew printing, the material passport also connects colour qualification to pattern engineering and marker planning. Reactive printing requires steaming, washing and drying after ink deposition, whereas pigment printing relies on dry heat fixation, so mechanical relaxation through the finishing line differs by route.[S01] A cotton poplin or jersey that contracts during pretreatment drying or conveyor curing changes both its areal density and the geometric scale of the printed motif, requiring colourists and patternmakers to evaluate the same prepared physical cloth.[S12][S17]

Colour accuracy fails operationally if the right shade lands at the wrong scale, orientation or seam position. Prepress translates visual artwork into a dimensionally locked production file mapped onto valid sewing patterns.[S09][S32] Scaling a graphic arbitrarily to fit an avatar or cropping without seam allowances and shrinkage rules distorts the assembled garment.

Research on computational and parametric pattern making confirms that a realistic three-dimensional garment model depends on valid two-dimensional pattern geometry, including seam correspondence, darts, grainlines and ease.[S09][S32] For all-over or engineered prints, prepress must map against released two-dimensional patterns rather than painting a mesh without unwrap checks, preventing motifs from stepping across side seams.[S09][S32]

GFT proposes a mandatory prepress lock checklist before any file enters the raster image processor (RIP):

• Locked physical dimensions and resolution: Specify width, height and repeat pitch in millimetres at the print plane alongside pixel density, prohibiting automatic driver scaling.[S21]
• Grainline and print direction: Fix pattern orientation relative to warp or wale direction, since rotating a panel alters stretch and directional reflectance.[S02][S09]
• Seam allowance and bleed: Extend background colour and motifs across the full seam allowance plus a cutting bleed margin to prevent white seam flashing.[S09][S32]
• Registration and piece markers: Place alignment marks and piece codes outside the finished boundary for accurate cutting and sewing.[S09]
• Graded placement rules: Define whether motifs scale across graded sizes or keep fixed dimensions relative to an anatomical landmark.[S32]
• Directional shrinkage compensation: Apply measured length and width contraction factors from the material passport only when backed by repeatable test data on that fabric and curing route.[S12][S27]

For garment decoration on ready-made blanks via DTG or DTF, prepress placement faces a different constraint: the garment is already sewn, and seam thickness, collar ribbing and tubular tolerances vary across pieces.[S15][S30] Prepress must define platen size, neck-seam stop, vertical offset from the collar seam and maximum printable width clearing armhole seams across the ordered size range.[S15] Printing an oversized graphic designed on a large avatar onto a small blank without a size-specific check forces the operator either to shrink the graphic arbitrarily at the console or to print over raised seams, causing ink pooling, head strikes or poor transfer adhesion.[S15][S30]