The importance of durability testing when selecting a digital label press
Your business is about supplying your customers with products that will ‘do the job’ they are designed for, and look great doing it! They have to be fit-for-purpose. Let’s take for example a label needed for harsh environments like a paint-can. Fit-for-purpose in this application means being scuff and scratch resistant, oil resistant and probably having a good lightfast capability.
So when evaluating a digital label press that will be required to produce labels for a harsh environment, it would make sense to thoroughly test these areas of the label, as well as image quality. We always encourage people to develop a good set of durability tests that can be used to compare different digital labels. Simple aspects like the way curing is managed can have a huge impact on ink adhesion – something that can only be identified with proper scratch testing.
FFEI and its technology partners (Fujifilm, Xaar and Edale) have heavily invested time and resource into ensuring a Graphium-produced label has a unique level of robustness under industry standard scratch testing. To pass, the surface of the label must demonstrate exceptional adhesion, durability and scratch resistance.
At a very top level the scratch test involves 5 steps
1: The X hatch tool is used to just break the surface of the ink not all the way down through the substrate/adhesive.
2: Then you brush away any debris caused by the cutting. In an ideal world this should leave you with a perfect grid pattern.
3: Apply the tape over the scored area and rub down. Normally you would apply and then peel off a few seconds later.
4: Support the substrate (especially if it is thin) and then pull the tape off. The angle and speed at which you pull the tape off will have an effect on the test. A firm, even and consistent motion is more important than the actual angle, make sure you do the test the same way each time to gain good comparative results. I usually inspect the tape visually and put it on white paper to make it easier to see.
5: Examine the grid for missing ink. This can be expressed on a qualitative scale (1 poor 5 good etc) or you could quote a percentage remaining or percentage removed.
These photos show a scratch test performed on the ‘Tip-on’ label we recently produced for Label & Labeling magazine.
Scratch the label
Apply tape and firm down
Rip-off, place and examine
The Graphium difference
Unlike many digital presses, Graphium prints on a very wide range of substrates with no special treatment thanks to built-in corona pre-treatment, yet maintains this incredible durability. This is a result of the unique formulation and technology in the UV curable ink in combination with the design of the Graphium press.
Specifically, Graphium has an array of UV LED lamps between every single inkjet print bar. This provides the ability to control the spread of ink droplets, using a precisely controlled dose of UV light. This process is called Inter-colour pinning and it provides a number of benefits unique to Graphium.
Firstly ink adhesion and image quality can only be effectively managed if you can control and balance ink on substrate, and ink on ink behaviour. The dose of UV light semi-cures the ink at the contact point of ink and substrate and leaves the ink droplet surface wet. This clever technique provides controlled wet on wet printing, which allows each ink to bind to the next, influencing the adhesion properties. It also allows ink to form a high-density film on the substrate surface that increases gloss, vibrancy and gamut.
Other UV inkjet devices lay down multiple layers of ink before any curing takes place, which means there is only control on selected substrates. Consequently there is a higher range of print artefacts and a reduction in print clarity. Graphium provides exactly the right level of UV light for every colour and at an amount that is precisely tuned for the substrate and print speed.
The power level of UV light per colour is controlled by software enabling the parameters to be stored for each substrate along with all other parameters related to substrate calibration. Including registration, print head setup, Vetaphone settings and colour profiles. These settings are held within Graphium media scripts – Which are essential to managing a fully colour calibrated system.
So at a variety of speeds on a very wide range of substrates Graphium is able to produce the most durable prints and image quality on the market today. If your customers need labels that are unquestionably robust in their final application – nothing beats a Graphium print.