HP's existing family of Vivera dye-based color inks provides a leading combination of image quality and display permanence. The new HP Vivera pigment inks take this performance a step further by vastly improving display permanence and providing water-resistant (and in some instances, waterproof) output on a wide range of print media. The new HP Vivera pigment inks do not replace dye-based Vivera Inks, but provide an additional, more flexible solution for creative professionals.

Precise, Long-lasting Color
New pigment-based HP Vivera Inks are specially formulated to produce a broad color gamut, deep, rich blacks, and true, neutral grays on a variety of media for brilliant, life-like photos and fine art prints. HP carefully designs and combines exclusive pigment inks to provide excellent color rendition and fine gradations within the color space for accurate, consistent color. Exclusive HP pigment photo inks offer additional benefits for professional photographers and designers, from exceptional fade resistance and durability to support for a wide range of media types.

Figure 1

EET, in combination with HP's proprietary ink vehicle design, results in inks that form a smooth film without the bumps or irregularities that often result when printing with other pigmented inks. This allows the HP Photosmart Pro to deliver excellent gloss uniformity across a range of colors and exceptionally high gloss on glossy papers.

HP's unique stabilization technology and ink design produce a highly stable pigment dispersion that resists pigment settling, a common occurrence with lesser quality pigment inks. The key to delivering a reliable, consistent ink is to ensure that pigment particles do not stick together and form larger particles. EET maintains particle separation and helps provide dispersion stability for reliable, consistent printing performance. As Figure 1. shows, each pigment particle is encapsulated in a resin layer. The layer creates a protective barrier around the particle and keeps it from getting too close or adhering to neighboring particles. Negative electrostatic charges within the resin layer further enhance the repulsion force between particles.

HP's unique EET design results in a freer-flowing, less viscous ink, so printhead nozzles operate efficiently, even after relatively long periods of exposure to air. EET enhances the ink's shelf life and helps promote consistent, highquality printing.

Various methods are used to compare the darkness of black inks in the context of print quality. While viewing of actual print samples is generally considered optimal, inclusion of full-size prints is not possible here. Another common method uses L* minimum to measure darkness levels of black output (the lower the number, the darker the black). The graph in Figure 2. shows such a comparison.

Figure 2

HP Vivera inks include gray and light gray ink to produce true, neutral grays, avoiding the use of composite inks.

As with all HP inks, the new pigment-based inks are carefully co-developed with HP printhead design to deliver highly accurate, precise drop placement even at high print speeds. Inks with even slightly different fluid properties would detract from this optimized genuine HP performance.

Permanence and Durability
HP Vivera pigment inks deliver exceptional display and image permanence across a broad media set. Image permanence essentially describes how long a photo will last and is determined by how well the photo resists relevant degradation factors. For example, a displayed photo may experience noticeable changes such as fading due to exposure to light (light fade), air pollutants (air fade), or high temperatures. Other degradation factors include thermal or dark fade, which refers to image degradation due to the absence of light, and humid-fastness, defined as the migration of colorant when an image is exposed to elevated levels of humidity.

Light fade
The basic method for estimating light-fade resistance accelerates light exposure and calculates years of image resistance to fade based on the accelerated light exposure. There currently are no standard methods for estimating and accelerating pollutant-induced fade. To determine potential susceptibility to pollutant fade, HP tests products under concentrated ozone conditions.

Air fade
Although longer term display of any type of photo should be behind glass or other protection, HP recognizes the importance of photo printing technology that is highly resistant to the effects of airborne pollutants. In unprotected display in direct contact with indoor air, HP Vivera pigment inks offer several decades of ozone fade resistance on recommended papers. Please refer to the HP Photosmart Pro 9180 User's Guide for a list of recommended papers.

Water resistance
During the development of HP Vivera pigment inks, HP paid close attention to the various types of water resistance performance characteristics most important to customers. HP developed a set of six tests: Water Immersion, Standing Water Drop Evaporation, Standing Water, Water Spray, Water Drip, and Wet Smudge. To meet HP's stringent definition of waterproof, photo prints must pass all six tests. HP considers prints which pass all but the first two tests as water resistant, although not waterproof. Prints produced using HP Vivera pigment inks and HP Advanced Photo paper pass HP's definition of waterproof and on many other papers produce water resistant prints.