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.
That lower resolution does have an upside, however. “With inkjet, you are looking at a speed advantage,” says Crowley. “What you will generally find with inkjet is that to achieve the higher press speeds, they need to trade something for this, and that is generally print resolutions.”
As an example, Xeikon’s PX3000 Panther inkjet press has a print resolution of 600x600dpi but a top speed of 50 metres per minute, whereas its CX3 Cheetah toner press can print at maximum 30 metres per minute – but at 1200x3600dpi. “It’s a lot quicker to lay down three hundred and sixty thousand dots with inkjet than it is to print more than four million dots with toner,” says Crowley.
“If the expectation or requirement from the customer is the best in quality, then a dry toner press is the best option. If the customer has longer print runs and does not have the same high resolution and quality requirements, but also needs the additional characteristics of what UV inkjet has to offer, then an inkjet press will be the ideal fit,” he adds.
Safety first
In the eco-conscious world we live in, it is important to consider the effect that printing technologies will have on the environment. All businesses today are under pressure to ensure that they are green, and that any waste they produce does not have an adverse environmental impact.
The greenest options for printing are dry toners and water-based inks. “The biggest advantage of both of those is that neither one produces any dangerous chemicals or waste,” says Crowley. “Waterbased inkjet sits in a similar space, because aside from the pigments or resins used, the byproduct is fundamentally water.
“With UV-curable inkjet products, you have a completely different set of byproducts to work with in the manufacturing process, the curing process, and the disposal of things like canisters and containers.”
Food safety and regulatory compliance is a similar area of concern. “A lot of printing technologies are used in food packaging as well, so there are sustainability and compliance issues there,” says Crowley.
Dry toners are among the safest technologies for food packaging. The biggest issue with UV technologies is migration: some of the initiators that they use can migrate through certain materials if not cured correctly, so if using UV, you need to consider things like physical barriers when you are manufacturing a label or a package in order to minimise migration and contamination.
“Water-based is the only inkjet technology that has a strong position around minimisation of contamination for compliance,” says Crowley
Application, application, application
Ultimately, says Crowley, the decision whether to invest in toner or inkjet comes down to your target markets. “The question is what market do I sit in?” he says. “What best suits the application and the customers that I’m talking to? You may think you want the speed of inkjet to print wine labels. Well, that may not work from a quality perspective– you may want to look more at a dry toner application for that.
“You may want a 12 to 18-month life cycle, a durable application. Well, though some toner has good light fastness, it would not achieve that sort of outcome – inkjet would be better for that. Inkjet has a lot of applications in the durables space. It tends to work well with issues like scuff and resistance, and paper stocks are where you’d tend to have trouble with it,” says Crowley.
While durables are inkjet’s forte, finer or higher-resolution work is where dry toner excels. “Anything that goes under the sink, anything that is in a workshop or an industrial application, realistically what you would be looking at is an inkjet technology,” says Crowley. “On the other hand, if you are in food or pharmaceuticals or wine and beverage, you will be looking at toner.
“Not every solution can be everything to everybody, so mapping out what markets you’re targeting can help you find the right solution for your digital applications.”