Mastering White Ink Optimization

White ink plays a crucial role in flexography and gravure printing, often accounting for at least 30% of total ink consumption. Achieving an excellent opacity—where the ideal colorimetric values are maintained even when printing on black—is a fundamental requirement, not just an added feature.?

Two primary factors influence this:

1. Leveling: Proper leveling ensures uniform ink distribution, preventing issues like “hollow microdots” that compromise opacity. This aspect is so vital that I’ve covered it extensively in my writings, particularly on the importance of target parameterization. Without proper leveling, achieving desired opacity is simply impossible.

2. Mass Deposited: A straightforward way to verify the correct amount of white ink deposited is the “candling” test—hold a printed sheet up to a light source; if the light does not pass through, the deposition is likely adequate. If what you see in backlight is orange, your deposit is reasonable but oh well, then to correct inadequate opacity, consider adjusting the anilox roll: choose one with the highest LPI (lines per inch) available and work at the maximum transfer viscosity determined from your dilution curve—a topic I’ve elaborated on several times before.

For those seeking to expand their color gamut or operate within an extended gamut (EG) range, gloss becomes a critical factor, directly impacting the volume of the ICC profile. This challenge is largely addressed by the ink supplier’s choice of titanium dioxide, resin system, and attention to Pigment Volume Concentration (PVC, a lot of ink manufacturers do not even know the term). Proper drying is also essential—residual solvents must not exceed the solubility parameters of the system, as this would compromise opacity.

While in the pressroom, options to adjust these parameters are limited beyond leveling and coverage. However, ensuring the use of the correct thinner is vital, particularly in humid climates where forming a ternary or quaternary azeotrope with water can help prevent the cooling effects that dull the film.

Strategic Optimization of White Ink

To achieve the maximum color gamut, your white ink must be neutral—free of undertones and perfectly leveled. Reducing white ink consumption without compromising print quality is not just desirable; it’s achievable, considering that opacity is influenced more by leveling than by sheer ink load.

The optimization process involves fine-tuning multiple variables: type of ink, anilox characteristics, double-sided tape, surface texturization of polymers, viscosity, dilution, substrate, plate pressure, and print speed. For added precision, consider the impact of temperature, drying air, and air turbulence—remember, in flexography, variability is the only constant.

Have you considered performing a "fingerprint" of the white?

Of course, because who would want to optimize all those variables you mentioned without first ensuring that the white is perfectly calibrated. Once you do that, it’s very likely—*highly* likely—that you'll find yourself in the ideal situation to achieve not only the best color reflection but also, of course, the maximum gamut. After all, what would printing be without that reflection and a glorious gamut, right?

Conclusion

The correct parameterization of white ink will yield significant advantages, from improved print quality to reduced costs.

If you’re keen to explore this and other related topics further, my book “Mirada Diferente” is available for free download on Apple Store, Google Books, or Amazon. This resource delves deeper into the nuances of flexography and gravure, providing valuable insights for professionals in the field.

Buen Provecho!.