scan htp works in the niche of transfer printing. We have no doubt that digital is the future. However, we still make use of conventional printing techniques like gravure and screen-printing in some textile printing projects.
This technical guide gives an overall description of the transfer technology, and then goes on to describing the technique of digital transfer printing. Finally, we take you through the two conventional techniques that we use.
There are of course a number of other printing techniques used in the textile industry and new techniques keep coming up. Our technical guide outlines the most common techniques in our textile projects.
What is transfer printing?
The idea of transferring a coloured object from one material to another has been in use for thousands of years. Ongoing development and patenting of the different techniques have been going on forever. In modern time, the heat transfer print is the technology used the most. In the heat transfer print process, the colorants sublime from the transfer paper to the synthetic fibre material under high temperatures.
During the sublimation, the colorant turns from a solid into a gas without becoming liquid at any time. It evaporates into the textile fibres. The molecules of the synthetic fibres open at the high temperatures; the fibres soften and absorb the ink. Once removed from the heat, the fibres will cool down and settle around the colorants. This technique provides very high colour fastness.
Only disperse dyes have the ability to sublime. The size of the molecules determine whether the colorant is suitable for transfer printing.
Transfer printing has many advantages:
- Multiple vibrant colours
- Sharp details
- Sorting of misprints on paper instead of fabric
- Quick change from one design to the next
- Transfer of ink and settling take place simultaneously – no need for further finishing
Digital print saves resources
Software and hardware work side by side when we print digitally. Not only do we control the print nozzles spraying ink onto the transfer paper, we also have the opportunity to match any shade from the original. We reproduce photographic pictures and very detailed patterns with great accuracy. The choice of colours is really only limited by the performance of the printer itself.
Preparation for the print process is minimal, and the small parties are not proportionate resource demanding. We print the number of metres you need for your project (length and width). The waste of fabric and paper is minimal. The digital control reduces the consumption of colorants significantly and therefore, we may recycle the transfer paper without worrying about surplus colorants.
Ongoing refinement of the technology provides us with new opportunities and new challenges. We develop our digital expertise accordingly to meet any new demand of sustainable production.
The digital printing process is significantly slower than the conventional printing techniques. For large parties of fabric and limited requirements of colours and details, the conventional printing techniques remain the most cost-effective.
Gravure print (cylinders)
Gravure printing involves engraving the pattern on copper cylinders coated with nickel or chromium. The colour paste is applied in the pattern grooves, and a scraper removes the surplus colour.
Each colour has its own cylinder. The technique may take place with our without intermediate drying of the transfer paper.
Preparation of the cylinders is time-consuming and quite expensive. We justify, however, using this technique for large parties of fabric due to a very high production speed.
The repeat size depends on the diameter of the cylinder and therefore, the maximum size is usually 60 cm.
Screen printing uses hollow screens of metal (nickel) perforated in different meshes. The raw screens are coated with varnish in which the pattern is made. During the printing process, the colour paste is applied into the screen via distribution pipe. The colour paste is squeezed through the openings of the screens. One screen per colour.
Preparation for the printing process is laborious, but once you activate the start button, the printing is fast. At large parties of fabric, this technique is probably the most cost-effective.
The circumference of the screen normally limits the repeat size, but in some cases, it is possible to extend the repeat size.