Screen print Vs. digital print
When it comes to printing sign and display graphics there's a basic choice between two print technologies, screen printing and inkjet. And while the digital option has clearly become the dominant technology today, there's still plenty of life in screen printing with Fujifilm, for example, reporting inks sales at roughly 50-50 between screen print and digital. So it would seem that each technology has its own advantages, depending on the applications in hand.
Digital is best suited for producing very short runs down to one at economical cost. It’s good for turning jobs around quickly and particularly good at handling variable data applications. There’s a choice of different types of inks that are suitable for a wide range of substrates and different applications, from flexible vinyls such as vehicle wrapping through to rigid boards such as PVC foamcore that are structurally rigid. Digital printers can produce wide colour gamuts from CMYK inksets, with many also offering light cyan and light magenta to improve colour gamut and gradation at higher speeds.
Screen printing on the other hand is an analogue process. The first step is to split the image into separate colours and create one screen for each colour, with the ink then being applied one layer at a time to build up the complete image. This allows for the inks to be laid down in relatively thick layers to produce images that are noticeably more vibrant than with digital printing.
The drawback is that it costs time and money to create the screen, which makes it costly for short runs. But this method is extremely cost effective for producing longer print runs. The longer the run the cheaper the unit cost of each item. This means that screen printing is still a viable option for many graphics applications like retail displays.
But many of the digital vendors are also eyeing up this market and so there are a number of large UV inkjet flatbeds such as the Inca Onset series or the HP FB10000 that are also capable of coping with relatively long runs. However, it’s not uncommon to find both digital and screen print combined, with the special effects and white backgrounds produced on the screen printer and other colours added via a high speed flatbed, playing each technology for its strengths whilst minimising ink costs.
Screen printing is a mature technology so little has changed in the last few years in terms of print speeds and resolutions and overall capability. Indeed, most of the recent changes to screen printing inks have been prompted by legal requirements. So for example, N-Vinyl Caprolactum or NVC, which is a monomer that’s often used in screen printing inks, was recently reclassified for health and safety reasons. This in turn will mean that many ink vendors will now have to reformulate their inks to avoid using it.
Nonetheless, James Whitehead, product manager for Fujifilm’s screen and wide format inkjet inks, says that Fujifilm still sells a lot of screen printing inks, pointing out: “There are print buyers who still specify screen printing because they like the colour saturation in particular.”