Page 32 - Print 21 Magazine Jan-Feb 2019

Digital Printing
Toner or inkjet?
The digital debate
The digital printing space is dominated by three technologies, each with its own strengths and weaknesses: dry toner, liquid toner, and inkjet. Figuring out which one
to buy can be a tricky prospect. Jake Nelson spoke to industry experts to find out the pros and cons.
Though all three are digital printing processes,
dry toner, liquid toner
and inkjet all work in different ways. Deciding between them means working out
the market segment you’re looking to target, advises Trevor Crowley, sales general manager at Xeikon, which manufactures both dry toner and inkjet label presses. “Getting a better understanding of what market you’re trying to secure will help you drive part of the decision process as to what technology you take on board,” he says.
Between them, dry toner and liquid toner (HP Indigo is the only liquid toner system) make up the majority of the global digital label and packaging markets, with
inkjet a relatively new entrant. “Dry toner is what is referred to
as electrophotography,” explains Crowley. “You have a drum which picks up an electric charge, and that charge works to stimulate the transfer of toner onto the drum; another charge is then used to drag that toner across to the paper. You put down a number of smaller dots, then fuse that. This cluster of dots will form the finished image.”
Inkjet has a smaller market
share, but Crowley sees demand increasing for it. “Inkjet offers a different characteristic to what
you see with dry toner, whether
you use a piezoelectric head to generate droplets or something like a bubblejet heat system,” he says. “You
fundamentally have two types of inkjet – one where the head is static and the substrate passes underneath, and one where the substrate is fixed and the head moves across it.”
Speed and quality
One point of divergence between toner and inkjet is the question of speed versus quality. Each method excels in one area, but lags behind in the other.
For toner, the main advantage
is image quality. “At this stage, electrophotography still offers the best image reproduction,” says Crowley. “Currently, it offers the highest resolution, which is why toner is used most often in high-quality output, be it in labelling or commercial print.”
Inkjet’s Achilles heel in terms of quality is dot gain, says Crowley. “You may see an issue with dot gain, which you would traditionally see with offset or flexo – you have a liquid which wants to wet out before it dries, and that applies whether it is water-based ink or UV,” he says. “You need to then compensate for that gain process, where with dry toner that is not an issue.
“With dry toner, what you put down is what you end up with.”
Dot size is also a factor: currently, the smallest droplet an inkjet press can produce is around four picolitres, which translates to 12-13 microns, compared to 4-5 microns from
dry toner. “That impacts on the resolution as well, so you need to consider that,” says Crowley.
32 Print21 JANUARY/FEBRUARY 2019