Digital Printing

Heres a bit of information how digital printing is done....

The idea of digital printing on textiles has been around for some time.  Carpet inkjet printing machines have beenused since the early 1970s.  Digital ink jet printing of continuous rolls of textile fabrics was shown at ITMA in 1995.   Again at ITMA in  2003, several industrial inkjet printers were introduced to the marketplace which made digital printing on textiles the new industry standard.  These new generation machines had much higher outputs, higher resolution printing heads, and more sophisticated textile material handling systems allowing a wide varieof fabrics to be printed.

One reason for the comparatively slow growth of digital printing on textiles may be related to the  extreme demands of the textile applications.  Although ink-jet printing onto fabric works in fundamentally the same way as any office type ink-jet prints onto paper, fabric has always been inherently more difficult to print due to its flexible nature.  The level of flexibility varies from warp to weft and with each degree around the bias, so guiding the fabric under digital printer heads has proven to be very challenging.  Other challenges:

• There are many  types of synthetic and natural fibers,   each with its own ink compatibility characteristics;
• in addition to dealing with a fabric that is stretchable and flexible, it is often a highly porous and textured surface;
• use requirements  include light fastness, water fastness (sweat, too) through finishing operations and often outdoor use, heavy wear, abrasion, and cleaning;
• the fabric not only has to look good but to feel good too;
• fabric has much greater absorbency, requiring many times the ink volume compared with  printing on papers.

Before any printing is carried out, the designs need to be developed in a digital format that can be read by the printers. Thus, all development has to be based on co-operation between the design software companies, the ink manufacturers and the printing machine developers.

In the face of such odds, digital textile printing is happening.  And how!  Digital inkjet printing has become one of the most important textile production printing technologies and is, in fact, transforming the industry. It has been influencing new workflows, business plans and creative processes. The opportunities for high-value digital printer applications are so large that many hardware and chemistry vendors are investing heavily in textile and textile-related products and systems. Between 2000 and 2005 digitally printed textile output rose by 300% to 70m square metres.  This is still less than 1% of the global market for printed textiles, but  Gherzi Research, in a 2008 report, suggests the growth of digital printing on fabrics to be more than 20% per year.  This growth is largely driven by the display/signage sector of the market; it is only recently that interior designers, seeking unique solutions for their clients, have been turning to digital printing.

Digital processes have become so advanced that it is becoming very hard to tell digitally printed fabric apart from fabric printed the traditional way – although for my money, they’ll never replicate the artisanal hand crafted quality of hand screened or hand blocked prints, where the human touch is so delightfully evident.  The lower energy, water and materials consumption means that more printers are switching to digital as it becomes competitive for shorter runs.   Although there are many advantages already to digital printing, the few downsides, such as lower production speeds compared to rotary screen printing and high ink costs are both changing rapidly.

As with traditional screen printing technologies, the variables in digital technologies are as varied as in screen printing,  with additional complexity of computer aided technologies requiring changes from the design stage onward. Digital textile printing output is a reflection of the design and color management software (such as Raster Image Processing or  RIP) that provides the interface between the design software and the printer, the printer itself, the printing environment, the ink, the fabric, the pre-treatment, the post-treatment and last, but not least, the operator.

This print method is being heavily touted as the “greenest” option.  Let’s find out why they make these claims.

In theory, inkjet technology is simple – a printhead ejects a pattern of tiny drops of ink onto a substrate without actually touching it. Dots using different colored inks are combined together to create photo-quality images.  There are no screens, no cleanup of print paste, little or no wastage.