IIJ: The Freedom to Print Digital Wallpaper

IIJ: The Freedom to Print Digital Wallpaper

Image: Paddy O’Hara

I recently caught up with Paddy O’Hara, John Corrall and Veena Sarojiniamma of Industrial Inkjet Ltd in Cambridge, UK to speak to them, and to view their new inkjet wallpaper printing machine. This machine represents a departure into new territory for the integrator who previously had built its business around developing bespoke technology with inkjet for a variety of manufacturing uses. I visited them to find out more.

How is this inkjet wallpaper machine different, and why have you developed this specifically for the wallpaper market?

Traditionally at IIJ, customers would come to us if they couldn’t see a machine available in the market and we would most likely develop something new for them. They would go around all the standard machine suppliers and if they couldn’t get what they wanted, then they would come to us and ask us to help.

What is different this time is that with wallpaper printing we saw an opportunity and we developed something that we think the market both needs and will really value. The total amount of wallpaper produced in the West has been in decline for some years and we see a real opportunity for digital print to reverse this trend.

How has your business changed over time?

Back at the time of the first InPrint in 2014, we saw our future as likely to be focused on the robotic stuff along with individual projects.  However, because every robotic project is different we soon discovered that you get very little leverage from one project to the next. And whilst this develops your expertise and ability to solve complex problems, you just don’t get a lot of repeat business. Additionally, the robotic stuff is really hard as it takes up so much of our expertise and our time.

So we had a choice, to invest in more people to respond to this demand, or focus on less engineering-hungry stuff and select and develop new technologies that fulfill a particular need. This is why we developed this machine.

So this shift, how have you managed this from a technical perspective?

A crucial element that has helped us to develop this machine is the fact that software has become better and better at enabling overall production. The inkjet world has changed over the last few years in that customers can now take it as read that the performance of the inkjet system and the ink will be totally reliable. A lot of our project work now is in system software. For example, a typical system from us these days will automatically access the customer’s database for print data, carry out in-line camera verification of the print and then generate an automatic report on the data used and any defects detected. Another example is splice-handling – detecting a join or splice in the media and lifting the inkjet printheads out of the way in time.

With traditional high-volume Wallpaper printing, the image is a simple pattern that repeats every 600mm. But a very important segment of the wallpaper industry now is the “mural wall” market. Here the image being printed is a single large picture – the size of a wall, or even a room. The software has to take such a large image and cut it into a number of wallpaper “drops” that will then be printed in sequence by the inkjet system. If a problem occurs during the printing then you want to be able to reprint only the defective “drop”. You don’t want to have to re-make the whole job.

Colour management is also very very important with Wallpaper printing. One customer said to us that “wallpaper is colour”! The inkjet system needs to be very accurate at reproducing the correct colour on each kind of media day in and day out.

Another opportunity that software enables us to meet is embossing. Or more accurately “embossing without the fuss”. Embossed wallpaper is very important in the market. With conventional analog printing, due to web shrinkage or stretch, it’s not unusual for the embossing to not quite line up with the printed pattern. The Wallpaper producers are then faced with making a new embossing plate to match the print – which obviously costs. With inkjet, the software can simply grow or shrink the printed image to match the embossing. In theory, this can even be done in real-time using a camera system to track any alignment error – ie the image to print is constantly being stretched or shrunk in two axes.

What other benefits does the system give?

Like any other inkjet project, the economics have got to be right. When we started the project we were worried that the final cost-per print would turn out to be too high for the high-volume mass-production market. We knew that our ink costs would be much higher than “conventional” inks (eg. rotary screen or flexo), but we hoped that this would be compensated for by the lack of any setup time or tooling.

John Corrall, CEO

Image: John Corrall, CEO

It turned out that it wasn’t just labour costs that digital print can save, it’s also the costs of the printing screens and plates and the large amount of space needed for their storage. We also saw that conventional wallpaper presses can generate a large amount of waste – the paper and ink used during the set-up of a new job. Because spot colour inks for conventional print are mixed on-site then a small error there can result in a lot of waste. All of these costs combined are currently preventing the volume producers from being able to handle shorter runs.

We did quite a bit of cost modelling to compare inkjet against conventional print and we were very pleased to see that our print costs appear quite comparable.

Another benefit of inkjet is the ability to quickly correct the colour. If you have ever done some DIY you will know that you have to buy wallpaper rolls that are all from the same batch. The same design of wallpaper from different batches won’t “match” on your wall. The differences may be due to a subtly different “mix” for the conventional spot-colour inks, or it may be that the media has changed slightly, or it might just be environmental issues such as humidity or temperature. With a digital system, the colour output can be quickly re-calibrated to take into account any effects of the media or the environment. Colour variation between batches is going to be greatly reduced or eliminated.

What about the Challenges?

Well, right now we are only using CMYK process colours. So the colour gamut is not perfect. As with other inks in other applications, there are usually some Pantone colours that we can’t hit – for example, Coca-Cola red. Having said that, the inks we are using have a high pigment loading and produce strong colours and initial customer feedback has been very positive.
We were also quite surprised during one of the early customer demos at the edge-to-edge colour accuracy needed. Obviously, each “drop” of wallpaper has to accurately match the colour of its neighbour. The human eye is not sensitive to a gradual colour shift across the wallpaper roll, but it picks up a sudden step in colour as would happen if the left edge of one “drop” didn’t match the right edge of its neighbour. Luckily we can individually adjust the colour density from each of the Konica Minolta printheads that we use, but as a result of that feedback we have had to really tighten up our colour calibration specification for each system.

Head of Ink Technology - Veena Sarojiniamma.

Image: Head of Ink Technology – Veena Sarojiniamma.

The main challenge throughout the project was to develop an ink that met all of the regulations for Wallpaper, and at the same time looks and feels like Wallpaper. And it must do this on a wide range of standard wallpaper media – PVC, Paper and non-woven. It didn’t take us very long to find an ink that would pass the tests for abrasion resistance and wash-resistance, but the print samples we produced with it were not acceptable to the Wallpaper customers. Wallpaper cannot be glossy at all – customers expect all print to be completely matt. This has been the hardest part of the project. During the project, we fully tested something like 15 ink formulations – at a cost of many £ thousands each.  Understanding the regulations and the customer demands and developing an ink that meets all of them has been the responsibility of  Veena Sarojiniamma. She and her team should take most of the credit for the project’s success.

So what kind of production is this for, mass production or for the short run mural market as you say?

Basically both.

The mass- production people are excited by it as they can see the potential in the flexibility and productivity improvements it can deliver. Basically, it gives them the ability to do short runs economically. They do need speed though. 60 to 70metres/mite is the typical press speed that they want the inkjet to duplicate.

The second market we see this as relevant for is mural wall. For them, the speed is not so important. During one of the customer demos recently the customer’s staff did a double-take and said “wow” when they saw it run – and that was at only 30metres/minute. We tend to forget that this is still very fast compared to a wide-format printer 30metres minute is 500m2/hour.

The mural-wall customers who have seen it accepted the print quality and speed immediately and then rapidly moved on to the question of software. For the mural-wall application, the front-end software becomes far more important. It’s mainly the ability to handle giant image files efficiently – without long delays while the image is processed. In other applications, we have used Colorgate software for this, but in the Wallpaper market, AVA is in strong position. In addition, direct web-to-print software is going to be important for at least part of this market.

Interestingly the mural-wall people don’t expect to spend much time adjusting the image or adding effects. Or if they do that it’s done off-line away from the printer. The main requirement is for accurate colour reproduction of the original image file, followed by speed of image processing and then a very simple user interface – ideally an almost automatic workflow to give hands-off operation. This also implies the need for some automatic pre-flighting of the image file, for example, to make sure the dpi is adequate or to cost the job.

For both sides of this market, we need to be able to print on “standard” media used in conventional production (rather than expensive “digital” media) and the image must be sharp and matt with good solid-block colours. We need to be able to print onto pre-embossed or textured media (which means the ink will need to fly a long way through the air). Finally, the print has to really look and “feel” like Wallpaper.

How much will the cost be for this system?

We expect to sell the inkjet system as either just an inkjet module – for fitting to an existing press – or as a complete stand-alone system. The module-only solution is more likely to appeal to the mass-production market. As an example, depending on the spec of the paper transport we expect the price for a complete stand-alone system to be of the order of UK£500K. Obviously, the inkjet module by itself will be significantly less.

What’s next?

We lost a few months earlier this year due to some issues with the ink, but these now seem to have been resolved.

On the mass-production market, our current goal is to get a system into a UK based supplier for a thorough beta a trial. We have had some offers for this- customers are keen. Before the install we still need to make sure that we can achieve the specified print speed though (70m/minute)

We are probably further on with the mural-wall market. Customer demos in IIJ have gone well and we are moving into full customer trials here. There are still issues to sort out on the workflow software but these don’t seem to be difficult to resolve.

How long has this taken?

We have been in development for 2 years now. Most of that time has been spent on ink testing. Before we could start the ink work we had to study the regulatory requirements for emissions, wash and scrub testing and buy the correct test equipment. We put a lot of work into studying gloss level of the printed ink and we talked to a lot of customers to understand the range of wallpaper media that they would want to use (we have a target list of 42 media!). Once we had all of that information it took us 6 months to realise that we couldn’t get there with our current inks, and after that, it took a whole year to develop an ink that worked. This was simply a case of hard slog for Veena and her team.

Has it taken you longer as you have been working on this problem alone?

Before we started the project we did talk to established analogue press manufacturers but it seemed like our goals might not be easily aligned. In the end, we worked on the development by ourselves, with help and advice from some Wallpaper producers, and then sharing information with Konica Minolta as we go. We are delighted with the results we have achieved and we think we can now offer the market something truly unique. We think that we have developed something that has huge potential for both industrial mass production and short run commercial mural wallpaper production.

Our system combines speed with flexibility and good economics. In the end, this is about giving our customers more freedom.

For more information on Industrial Inkjet check out www.industrialij.com

If you have any questions or inquiries regarding the machine contact John Corrall johncorrall@industrialij.com