Inkjet Color

Pigment Or Dye Inks

Personal computer development and enhancements have proceeded at an unmatched pace, since their introduction in the 1970’s.  Today we may obtain powerful computer speed demons not even dreamt of just a few years ago.  And now digital printing technologies are catching up.

Photographic artist’s utilizing intense software packages, such as Adobe’s Photoshop, have demanded an up to date digital output.  Thirteen years ago the state of the art printers were dot matrix or color ribbon styles.  Laser printers were commandeered from the office and color capabilities added, but they had little color control and the print size was limited.  Expensive dye sublimation printers brought color control and longevity to the forefront, but size was still limited.  Inkjet printers have now stepped forward to meet that demand.

Inkjet developments, especially over the past five years, have brought lower prices, increased print sizes, finer detail with smaller ink droplet size, a better color gamut and the controversy over pigmented versus dye-based inks.  Lets explore the differences and similarities of both available media to see which fits your needs.

The term Pigment Base (non-soluble pigments) and Dye Base (water soluble dyes) inks both utilize water as the carrier as base for inkjet inks used in desktop printers.  Water is the carrier solvent in which the colorant component of the ink can be suspended or dissolved.  Water base inkjet inks are far more "family" friendly.  They are Non-toxic, non-flammable, and to this point non-carcinogenic.  These types of inks are much safer to use in a home or office environment and offer a more eco-friendly way of printing, as compared to the dangerous industrial oil or alcohol based inks.

Water-soluble Dyes are the more common of the colorants and generally provides the widest color gamut for color printing.  They are relatively easy and inexpensive to manufacture (compared to other types of inkjet inks).  They have the lowest support issues and can be used in the cheaper to manufacture print heads.  They also have some of the weakest longevity (permanence) ratings and have poor UV resistance, leading to fading at a swifter rate.

Pure pigment suspensions have long been common in black inks, but far less common in color inks.  Most Canon, HP, and Lexmark printers used a pigment suspended colorant for the black text cartridges in their 4-color printers.  Modern black pigment suspension colorant requires no dispersant when used as a text grade colorant and has excellent drop formation control and excellent archival properties as well as high UV resistance.  It does not, however, work well in photographic applications because it does not blend well with other types of ink.  It also works poorly on glossy photo papers.

Pure colored pigment suspensions (including black suspensions for graphics applications), long thought to be superior, must utilize a dispersant to maintain proper suspension of the pigment particles in solution since like the text pigment; the particles are not soluble in water.  Most color pigments are made of chemically generated color plastic polymers that are ground to very fine particles then coated with a dispersant to help the particles develop a slight static charge.  The static charge helps keep the particles suspended in low viscosity bases (a thin base such as water) suitable for inkjet printers.  Unfortunately, the combination of the polymer and dispersant produces rather dull colors (low color gamut) and require very high pigment particle loads to produce results that are even moderately acceptable.  For years the use of color pigments was limited to the most expensive wide format printers, which could use complicated software to layer the pigments to produce more dense and vibrant colors.  Desktop printers could not use pure pigment colors except under the most high demand conditions, as the pigment would eventually clump together and clog cartridges and nozzles.

UltraChrome Inks, used by Epson, are really a different name for an encapsulation type of hybrid inkjet ink.  A few years ago, a hybrid ink was created by taking a standard color pigment suspension and adding small amounts of light fast dye soluble inks to the mixture to create a hybrid which offered better initial color matching than pigment suspension alone.  It did not have a long shelf life in liquid form and could sometimes cause the pigment to clump prematurely; it also presented a costly option.

Epson took the idea a step further.  They tinted the dispersant of the pigment suspension with a pure dye that was soluble in the dispersant.  The dispersants as a matter of process "encapsulates" the pigment particles.  However, with a tint, the pigment particles appear rounder since the colorant extends the color appearance of the pigment into the dispersant.

The UltraChrome inks are only special in that they are the first to offer this feature in a desktop application.  The final product is more stable than the old dye ink/pigment ink hybrid, but does not have the same "apparent" longevity of a pure pigment suspension colorant.  The dye in the dispersant does fade more rapidly than the pigment, but the overall faded appearance still exhibits more brilliance than a pure pigment print.  Additionally, the tinting process allows the pigment load to be kept within more stable limits giving the inks and much longer shelf life than a higher pigment load would have.  This method of creating a hybrid pigment style ink provides the best compromise between a vibrant color gamut and archival permanence.

If the new UltraChrome inks are superior shouldn’t I convert my printer to use them?  Using the newer pigmented inks in an older dye ink style printer is not a wise thought to entertain.  Before you consider this issue, you must be aware of the main differences between a printer engineered for dye ink and one engineered for pigment ink.  A dye printer is driven to place droplets in such a way so as to take advantage of the translucency of the inks in order to provide the optimum color match.  A pigment printer is driven to lay its ink in order to work with the opacity of the pigment.  A hybrid printer like the Epson Stylus Photo 2200 is driven to optimize the translucency of the dispersant tint in relation to the opaque pigment load.

Without special drivers to change droplet layering, no printer can effectively utilize ink for which it was not originally designed.  A prime example is the Epson Stylus Photo 7600.  The printer is sold as EITHER a dye ink version or a pigment ink version.  The driver software is designed to work with the specific ink type.  In addition, the service utilities (include physical components used to clean the print head) must be designed to work effectively with the type of ink in use.  A convertible version could be sold (that could use either ink), but would not make sense from a marketing or support standpoint.

Frequently, people have asked whether the Canon S9000 or the Epson Stylus Photo 1280 could run pigment inks.  From a purely technical standpoint, no they cannot.  The Canon S9000 runs at too high a rate of speed and utilizes too compact of a print head to allow a pigment ink, with sufficient pigment density to produce appropriate color effectively.  You would have to spend more time cleaning than printing.

The Epson Stylus Photo 1280 presents a different set of obstacles.  First, the driver is designed to layer translucent droplets, not opaque.  Second, while the print head is capable of handling most pigment inks, the cartridges are not.  There is a reason why the Epson 2200 utilizes a design with, in effect, no sponge.  The thick dispersant combined with the needed pigment load to achieve acceptable colors, would quickly bond to sponge surfaces reducing the replenishment rate of the cartridges.  The result is increased head cleanings to eliminate banding and, with long-term use, the possibility that agglomeration could occur in the print head itself, causing a permanent clog.

Two specific printer examples are given above, but the same reasoning applies to most other dye ink printers.  You should stick with inks that are formulated to take advantage of the features your printer offers.  Trying to make a purse out of sows ear could simply result in you being the price of one printer poorer.  In the end, it would be a huge headache trying to make your conversion work.

If you have the money to burn on cheaper printers, you can try to convert your dye printer to either pigment or hybrid style.  At best, you will get "barely acceptable" prints.  At worst, you'll be buying a new printer.

In another essay we will examine how to match the correct printer and ink with the best paper choices.

Compiled by askRodger@pictureline.com