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UPMSP Intermediate Dyeing Art study materials
UPMSP Intermediate Dyeing Art study resources

UPMSP Intermediate Dyeing Art: Textile Printing and Finishing Related to Dyed Goods

UPMSP Intermediate Dyeing Art · Work through your exam, one topic at a time.

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Textile Printing and Finishing Related to Dyed Goods

Printing is localised dyeing, so the same dye chemistry applies but the dye is delivered in a paste and fixed afterwards. Finishing alters appearance, handle or performance and can shift the shade of already-dyed goods - a frequent exam theme.

Printing methods and fixation

  • Block, flat-screen, rotary-screen, roller, transfer and digital inkjet are the main routes; screens give repeat accuracy and productivity.
  • Print paste contains dye or pigment, thickener (sodium alginate for reactive, guar gum, emulsion thickener for pigment), and auxiliaries such as urea, alkali or acid, and a reducing or oxidising agent as needed.
  • Fixation: steaming for reactive and acid dyes, thermosol dry heat at 180–210 °C for disperse dyes, curing at about 150 °C for pigment prints with binder.
  • After-treatment: washing-off of thickener and unfixed dye for dye prints; no washing for pigment prints.

Finishing that touches colour

  • Mercerisation with strong caustic under tension increases lustre, strength and dye uptake - the same recipe then gives a deeper shade on mercerised cotton.
  • Calendering, raising, sanforising change surface and therefore apparent colour and lustre.
  • Chemical finishing - softening, resin crease-resist, water repellent, flame retardant - may yellow whites, affect fastness or require curing that alters shade.
  • Stenter drying and heat-setting must be controlled to avoid shade variation across the width.

Worked example

A cotton voile is dyed to a standard navy, then mercerised. The shade comes out deeper and brighter. Reasoning: mercerisation swells the fibre, increases accessible amorphous area and dye uptake. Remedy: either mercerise the fabric before dyeing and dye to the standard, or re-standardise the recipe for pre-mercerised goods. Never compare shades between mercerised and unmercerised substrate.

Traps

  • Steaming a pigment print instead of curing the binder.
  • Forgetting that thickener must be washed out of dye prints.
  • Treating mercerisation as a purely mechanical finish.