\nThe classification of printing methods can be carried out based on:
\n\u2013 the printing process or dye application method;
\n\u2013 the machines used;
\n\u2013 the printing pastes.<\/p>\n
All printing processes can be combined with each other. Pigment and dye printing pastes differ fundamentally based on the type of bond created between the coloured paste and the textile substrate: of physical nature for pigments and chemical nature for colorants.<\/p>\n The type of physical or chemical bond determines: Pigment printing<\/strong> fabric back side<\/span><\/p>\n fabric front side<\/span><\/p>\n pigment printing: back side and front side<\/span><\/strong><\/p>\n 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.<\/p>\n 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.<\/p>\n Pigment printing process:<\/strong> 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:<\/p>\n We notice:<\/p>\n low colour fastness to rubbing with colour discharge and print fading<\/span><\/p>\n <\/p>\n laboratory rubbing test on pigment printing<\/span><\/p>\n \u2013 colour fastness to water washing: 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.<\/p>\n Colouring dyes<\/strong> fabric back side<\/span><\/p>\n fabric front side<\/span><\/p>\n fabric back side and front side, printing with dye<\/span><\/strong><\/p>\n After printing, the colour reacts chemically as in dyeing, and all textile fibres are died on both sides. Unlike pigment printing, before choosing the dye colour that will be used, it is necessary to consider the composition of the textile fabric, the dyeing method, and the colour fastness characteristics required for the final use of the item. Individual fibres are dyed with specific dyes based on the fibre composition and chemical characteristics of the dyes. There are listed below the most suitable classes of dyes and their most significant characteristics.<\/p>\n In the case of dye printing, because the bond between the fabric and the colour is of chemical nature, to each kind of fibre corresponds to the specific colour to be used, while in dyeing with pigments, as the bond between the fabric and pigment is of a physical nature, pigment dyeing can be applied to any fabric independently of its composition.<\/p>\n Problems in fabrics printed with dyes. Possible colour discharges due to low colour fastness to wet treatments, either due to improper choice of dyes or inadequate processing conditions. For each type of fibre, certain colour fastnesses, certain brightness and costs correspond to each dye class chosen.<\/p>\n In garments printed with light backgrounds, colour fastness is crucial, therefore is requiring a good.<\/p>\n colour discharge on a quilt washed with water<\/span><\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n laboratory test to check colour discharge in water washing<\/span> <\/p>\n <\/p>\n colour discharge on printed cotton with direct (low colour fastness to water treatments)<\/span><\/p>\n Flocked printing<\/strong> pink colour discharge after water<\/span> <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n detachment of<\/span> Laminated printing<\/strong> These garments can only be dry-cleaned with hydrocarbons as water washing causes shine loss and dry-cleaning with perchloroethylene causes foil detachment. \u2022<\/p>\n![\"\"](\"https:\/\/www.staging.detergo.eu\/wp-content\/uploads\/2024\/07\/3.GUIDA-LAVANDERIA_DETERGO_LUGLIO.AGOSTO_2024.jpg\")
<\/a><\/p>\n
\n\u2013 the colour resistance properties to various alteration factors that the garment undergoes during maintenance and wearing;
\n\u2013 the appearance and hand of printed parts.<\/p>\n
\nIn pigment printing, the processing cycle has the following steps:
\n\u2013 printing;
\n\u2013 drying and fixing without any subsequent washing.<\/p>\n<\/a><\/p>\n
\nThe printed fabric is treated with hot air (passing through an oven) at temperatures ranging between 140-160\u00b0C 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.<\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/u><\/p>\n<\/a><\/u><\/p>\n
\n\u2013 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.<\/p>\n
\nDye pastes are coloured solutions or dispersions with a suitable viscosity, consisting of dyes, thickeners and other auxiliary products (sequestering agents, catalysts, reagents, anti-foaming, hygroscopic, etc.). In addition to the dyes and thickeners, the auxiliary substances that make up the paste vary widely depending on the class of dyes and the nature of the textile substrate and the dyeing and fixing systems. Printing with dyes can be easily recognized when the back side of the fabric looks the same like the front side.<\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n
\nand dry-cleaning<\/span><\/p>\n<\/a>Dye-sublimation printing<\/strong>
\nThe sublimation process, also known as Sublistatica, named after the company that introduced it, is the most important and widespread in the textile printing industry. As mentioned, the principle involves first printing the design on paper using selected dispersed dyes that can sublimate at 180-210\u00b0C, and then transferring them to the fabric by heat. The only colour that sublimates is the dispersed colour, which only fixates to polyester. Colour fastness is good only for printing on polyester fabrics, as shown in the table below.<\/p>\n<\/a><\/p>\n
\nFlock printing consists in attaching short fragments of fibres, called flakes, to the fabric to form patterns creating a velvety effect. The printing involves three processing cycles: \u2013 printing the adhesive design; \u2013 application of flock \u2013 by flock we mean short fibrous material (0,2 to 0,9 mm) usually made of viscose or nylon (dyed paste). In the printed areas, the adhesive retains the flock, resulting in a uniform layer similar to velvet; \u2013 thermal treatment for permanently fixing the print by polymerizing the adhesive; \u2013 it is a physical and not a chemical bond, it is the same principle applied to pigment printing: flock detachment when dry-cleaning.<\/p>\n
\nwashing on on sublimation print in<\/span>
\nnylon fabric (low colour fastness to wet<\/span>
\ntreatments as shown in the table above)<\/span><\/p>\n<\/a><\/p>\n<\/a><\/p>\n
\nflocked dots<\/span><\/p>\n
\nA sheet of various coloured glossy effects such as silver, gold, etc., is applied on the fabric with pressure and glue.<\/p>\n<\/a><\/p>\n<\/a><\/a><\/p>\n