When Ink Takes the Blame

You may have heard the same thing as I have, many times: "The ink's intensity is low." ?

This phrase has become a classic, whether it's during a fingerprint conducted by a photopolymer manufacturer, when a print manager supervises a new job (or even some repetitive ones), or when marketing folks join the chorus. ?

And as is often the case, the culprit is identified almost instantly, with great conviction: It's the ink! So, without wasting time, the finger is pointed at the person in charge of the ink department—whether or not they manage a dosing system or in-plant—and if they can’t be found, the supplier is called in for explanations. ?

So, if you ever find yourself in a similar situation, before "shooting in the dark," ask yourself:

1. Is the white's reflectance curve close to 100%? This is so crucial that almost no one checks it. Seriously, if the white isn't leveled or sufficient, the overprinted color will inevitably be weak. ?

2. Is the cell volume appropriate? There's an obsession with high line counts, like 1000 lpi aniloxes with a 1 cc/m2 volume, as if that automatically guarantees quality... What a big mistake! If you're working with 133 lpi and want to print a gradient with 1% highlights, a 600 lpi anilox with a 2 to 3 cc/m2 volume will be more than enough. ?

3. Am I working at the maximum transfer viscosity? If you plot Intensity versus printing viscosity, the resulting curve is an inverted parabola, meaning it has a "peak" (actually, due to error propagation, it's a narrow plateau) where resolubility and therefore intensity is at its maximum. ?

4. Is the anilox clean? Over time, all aniloxes get clogged and worn out; this happens because the ink's resolubility isn't complete and because the blades, even if they're made of polymer, rub against the surface. If ultrasonic cleaning isn't performed regularly (where wear is also reported), your anilox could have a reduced cell volume, either due to occlusion or wear. ?

5. Is it pure or recovered ink? This point, though obvious, deserves attention. Don't you have leftovers in your company? And what do you do with them if not recover them? If the lab's ink extension equipment isn't calibrated to your anilox, it won't be able to infer the intensity correctly. ?

6. Is the polymer surface textured? These issues (crudely analogous to printing solids with 85-90% screens) are crucial for transfer, but those polymers aren't eternal... Could it be that the texturization has already worn off?

Allow me to share some experience... Inks don't have secrets; whenever they can, they spill the beans, even the mistakes!

Bon appétit!