On new papers and coating observations part 2
23 March, 2010 by
On new papers and coating observations part 2
Jon Cone

The strange thing about all this is that in 2005, Piezography Neutral K7 was released as a multi-toning ink system. But, instead of using color inks, it utilized the tone of the paper in order to arrive at a final color tone of the black & white print. It was able to achieve multi-toning through superior pigment technologies that combined to promote a pigment that utilizes light in a novel way. This is of course at the heart of the discussion that opened up on the Digital BW, The Print users list, and where I was heading to by means of explanation in part 1 of this opine. The Piezography practitioner who posted his finding on new papers there is quite used to the coating/paper changing the tone of his ink. The non-Piezography users are far less sensitive to this phenomena because they are used to manipulating the final color tone of their prints with color inks using software. Anyways, on the Digital BW, The Print two hypothesis were made in an attempt to explain the phenomena of how a particular new coating can change an ink from one tone to another - and that is what left me scratching my head in disbelief. The hypothesis were complex and rich and interesting, but way off the mark. One was that it is the amount of bleed in the paper that allows one of the pigments of a monochrome ink to dominate the others and was supported by a theory related to dropping ink on a paper towel which will cause different pigments to absorb at different rates. The other was an invisible new chemical reaction from pigment bonding to coating must be occuring which produces a new color. The very fact that these two hypothesis even existed made me realize that there really are two camps to black & white printmaking. One is made up of monochromatic printmakers who use monochromatic inks, and the other is made up of color printmakers who use color inks. Put in another way, one is made up of Piezography users, and the other is now made up of all the rest. It strengthened my idea for the need of a Piezography Archive. If my process is meant to preserve photographic values in a world gone digital, then it itself is not the beginning of the new age of color photography that now encompasses black & white prints. Piezography perhaps, is the final evolution of traditional black & white photography

So why do monochromatic inks change colors from one coating/paper to another?

It is easy to explain by describing how Piezography inks have been designed purposely to take advantage of coating/paper. When Neutral K7 was first introduced in 2005, it was marketed as an ink that could reproduce from cool neutral to sepia depending upon which paper stock was used. Many of the papers of that time are no longer manufactured. But some of the more recent offerings are creating tone possibilities we never imagined. The phenomena that perplexes the color ink user is simply an interaction between the light reflection/absorption qualities of both the monochromatic pigment and the coating/paper, and how humans observe color from light. Piezography pigments are now ground so small and coated with a clear polyester treatment, that they can no longer be considered 'opaque'. While they are not transparent, they are small enough and with unusual properties that light is absorbed both by the ink and by the coating/paper and reflected back through the ink to the eyes of the observer. The observer sees a different color depending upon the absorption and reflection of the coating/paper via the ink. In developing Neutral K7 as an achromatic ink (having neither more red, nor blue, nor green), I had to decide on one paper stock on which to produce this phenomena of neutral. I chose Hahnemuhle Photo Rag because at the time it was the most widely sold paper to my ink users base. It was smooth and had a slightly warm white cast. When Neutral K7 was released, the product would print perfectly neutral on this paper when viewed by a standard observer under 5000k illumination. Certainly those with some amount of color blindness, or those comparing it under differing white lights might see another tone of gray. It is no secret that paper manufacturers must add some amount of OBA (optical brightener agents) and pigment to their paper slurry in order to realize a specific 'white' and sell a consistent product even as their raw materials of cotton and sulfites varies from month to month and season to season. On top of these final sheets is an inkjet receptor coating that permits an inkjet printer to be used. The coating is the most critical part, in that it must control ink spread, promote ink absorption, and produces a delicate balance of sharpness, durability and smoothness. The final color tone of the sheet is made by the coating which also employs OBAs or/and pigments in order to meet the white spec of the paper manufacturer. The coating/paper itself therefore is one of the most vital components of an ink system that depends upon a paper for its final tone.

Note:The Neutral K7 *a*b axis on HPR (at least the HPR of 2004) was introduced within a range of 0.35 to -0.35 in both *a and *b of Lab color coordinates. *L of lab is used to identify darkness and lightness with a value from 0 - 100 (dark to light). The *a value describes the green (- numbers) or magenta (+ numbers) component, the *b describes the blue (- numbers) or amber/yellow (+ numbers) component. Incidentally, Lab was invented in the 1930s as a means to describe all of the color that the human eye can observe. This same system of color is at the heart of ICC color management and most scientific color analysis. We use Lab color measurement to develop K7 ink families and we very narrowly define the *a*b components of each shade in accordance to the *L value of each shade - and this is what allows us to make one profile that works with all of our ink choices.

Piezography Neutral K7 increased the fidelity of a grayscale image by dividing it into seven partitions. We went from four shades of carbon based black ink to seven shades. We were able to realize more fidelity in the print than even a specialty Eizo monitor can display. We have higher fidelity than silver or palladium. And we can far exceed the vision of the manufacturer of the printers we take over with our inks and profiling system. But in order to do this with aplomb, a new pigment treatment was emphasized to be sensitive to coating/paper when we made the new generation of ink, so that it also had the flexibility of color change without sacrificing fidelity. Although in its sixth year of production, Piezography K7 remains one of the most sophisticated inks ever developed for inkjet printing:
  • K7 pigment is sourced from the highest quality producers of pigment in Switzerland and Germany.
  • It is remanufactured using a nano-technology that was originally developed for producing the coatings used in JPL's Hubble telescope. Attention is placed not only on reducing particle size, but also on both the shape and facet reflection of the particle so that the quality of light that is absorbed and reflected by the pigment is carefully controlled.
  • The pigment is filtered to a very narrow band of particle size distribution to minimize any possibility of metamerism and to increase the perception of depth in the final ink layer.
  • Each pigment particle is physically surrounded in a polyester encapsulation to eliminate static charges to prevent clogging, and to absorb UV light.
  • Finally, each of the seven shades is individually formulated in order to restrict the *a*b to a very narrow range so that the final product does not modulate in color from light to dark and becomes extremely sensitive to the underlying coating/paper tone.
We found that we could imitate all of the PiezoTone ink sets with the new Neutral K7 ink by carefully selecting the paper stock. It was a nifty system to be sure at the time. Probably, like PiezographyBW ICC it was simply too far ahead of its time to be fully understood by a wide audience. I released another K7 ink set that was equally sensitive to paper stock, but offered a further range to warmth that was missing from the Neutral K7 possibilities. In order to shift Neutral K7 to Sepia (which was very popular), a very, very warm sheet of paper had to be selected, and our customers said they preferred to print Sepia onto much cooler paper. Sepia K7 was introduced. Eventually, I would release additional K7 ink sets (Selenium, Special Edition, Warm Neutral); each sensitive to final color tone when printed on varying sheets of paper. One more part should get my point out. I want to talk about polyester encapsulation as a key component of the observation of Piezography ink color change on different coating/paper. ...to be continued in part 3.
On new papers and coating observations part 2
Jon Cone
23 March, 2010
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