Textile printing: types, characteristics, and processing

These colorants can be defined as small-sized particles, generally of organic nature, not related to the fibre, insoluble particles that are deposited on the fibre and bonded to it through special synthetic resins – that perform their final binding action only after polymerization, by applying hot air treatment after printing. These particular types of dyes are then fixed to the fibres through resins that act as bonding agents; it is a physical nature bond rather than chemical, and this makes evident the low colour fastness to rubbing (the superficial coloured surface can be easily abraded) and also the low solvent fastness in dry-cleaning (the resin acting as adhesive will degrade and dissolve in the solvent). Therefore, we would like to specify that this printing process can be used for any type of fabric, regardless its composition. Pigment printing can be recognised by the fact that the back side of the fabric has a lighter colour than the front side.

The colouring pastes or pigments are deposited only on the outer surface of the fabric and is bonded through an adhesive: it is a physical and not a chemical bond as it happens in the case of dyeing. The reverse side of the fabric has a lighter colour because only a part of the dye is able to penetrate it.

Pigment printing process - The printed fabric is treated with hot air (passing through an oven) at temperatures ranging between 140-160°C for 3-4 minutes to cross-link the binder (polymerization) in order to fix the coloured pigment to the fibre and thus giving the garments acceptable colour fastness, especially to wet rubbing. After printing and drying, the print does not require any washing as in the case of printing with dyes, so the printed fabric feels a little stiff to the touch as the (synthetic) thickener has not been removed and the binder has formed a slightly rough layer.

Regardless of the printing process (applied or by corrosion, with thickeners, lacquered or rubberized), of the type of printing machine used (either manually, or hand-operated, or with a rotary table), and of the composition of the substrate, the quality standards of the colour fastness of the printing are:

We notice:

low color fastness to rubbing with color run-off and faded printing - laboratory rubbing test on pigment printing

– colour fastness to water washing: colour discharge;
– low colour fastness when dry-cleaning with perchlorine; the combined action of perchlorine and drying temperature causes degradation of the adhesive with consequent fading of the print and colour discharge.

In both water and dry-cleaning, the colour gradually fades with each successive washing due to rubbing during water washing or the combined action of perchlorine and drying temperature in dry-cleaning. When buying a printed duvet, it is advisable to check the type of printing: in the case of pigment printing, you should open the quilt to see if the inner side has a light colour, or rub the print with a solvent-soaked tester (rubbing is completely cancelling the print). When washed in a domestic washing machine, the quilt is pressed and consequently the print fades due to rubbing, creating problems with the customers; in these cases, it is recommended to make a declaration of indemnity after it has been checked that the item has a pigment print.