Transfer printing or thermal transfer is understood to mean various finishing techniques in which the print is on a carrier material and is applied to the textile with the help of pressure and heat using a transfer press. A distinction is made between digital transfers, screen printing transfers and foil transfers, also known as flex or flock transfers.
With digital transfer, a special flex film is digitally printed and cut to the contour of the motif. Then the motif is applied to the textile with a transfer press. There are transparent foils for white textiles. With this, the color penetrates the textile very well, so that hardly any application is noticeable.
With the white foils for colored textiles, the imprint has more the character of a sticker.
Almost every football shirt or other team sports shirt with a number and name is printed on textile using plotter foils. This method is very suitable for lettering, names, numbering and logos that are not too detailed.
With screen printing transfers, the carrier material is printed using the screen printing process. The screen printing transfers are produced in the same way as direct screen printing. However, the textiles are not printed directly, but rather the carrier material. Compared to direct screen printing, this has the advantage that the transfers can also be applied to demanding textiles such as soft shell jackets or similar. The advantages of screen printing transfers lie in the areas of durability, durability and color brilliance. On the other hand, the one-off costs for films and screen printing stencils are to be rated negatively.
The Direct to Foil (DTF) technique is similar to digital transfer. The difference, however, is that no white foil is printed, which then has to be weeded. Instead, the print is made using an inkjet printer and special inks, which are printed in reverse on a specially coated foil. A hot-melt adhesive is sprinkled on the still wet paint and gelled with heat. The print is then transferred to various substrates such as cotton, cotton blended fabrics, leather or even solid materials using a thermal transfer press. Colored textiles can be finished by using white ink as the underprint.
In digital transfer printing, a white carrier film is digitally printed with eco-solvent inks using the CMYK process. The motif contours are plotted directly afterwards by the combination device used (printing + cutting) and then have to be weeded, similar to flex and flock printing. Since only the underside of the carrier film has adhesive, the weeded motifs must be transferred to a second carrier film or taped before they can be applied with the transfer press. Elaborate, multicolored and photorealistic motifs can also be implemented for small runs.
Special materials are used in sublimation printing in order to achieve the breathable and imperceptible color application that is characteristic of this process. A sublimation paper is used, on which the motif is printed with special sublimation ink. As with any transfer printing process, the motif is transferred in the transfer press with heat and pressure. The sublimation ink has the unique property that it changes its physical state from solid to gaseous when exposed to heat, but without first liquefying. As a result, the ink – or color – is evaporated into the textile during the pressing process. Sublimation printing is only suitable for textiles with a high polyester content. Good color fidelity can only be achieved on white textiles.