Working with Ink-jet Inks

Working with ink-jet inks

Your printer uses dye based inks
Your printer uses pigment inks
The meaning of lightfastness when working with prints

The two main types of inks available for ink-jet printing are dye based inks and pigment inks. GOLDEN Digital Grounds can be used with both dye and pigment-based inks. Due to the constant changes in ink technology however, always test applications to make sure the ink system being used is compatible.

Dye based Inks

Dyes are colorants which are single molecules floating around a solution. This means they are very exposed to light and other elements, making them more prone to fading than pigment inks.
Dye based inks are more water sensitive than pigment inks. This sensitivity can be countered by either using absorbent surfaces or by sealing the surface with GOLDEN Archival Varnish before working on the print with waterborne materials. See Testing printed artwork for water sensitivity.

Pigment Inks

Pigments are clumps of inseparable molecules with less overall exposure to the elements, and therefore have a slower rate of fading than dyes.

Historically, pigmented systems tend to be less vibrant than dyes, but recent developments in ink systems counter this with the introduction of multiple cartridges, including more than one black and light versions of the traditional Cyan, Magenta and Yellow.

While the use of pigmented inks can usually allow for direct waterborne coating application, see Testing printed artwork for water sensitivity for more information about working on top of printed images.

Understanding Lightfastness Ratings from Printer Manufacturers
Lightfastness claims for 200+ years are not uncommon these days, but what does this really mean?
Lightfastness claims for digital prints are based on a combined system of printer + ink + substrate, with all products usually produced by the same manufacturer. From there the measurement criteria used by the printing industry is quite different that that used by the artists’ paints.

Artists’ paints rely on measuring changes to a color’s spectrophotometer reading based on the CIE L*a*b* color space. Depending on the degree of change, known as the Delta E (E), each color is then assigned a particular lightfastness rating set by ASTM standards.

By contrast, digital prints use densitometry readings to track changes in the density of a particular dye rather than measuring a shift in color space. In this system what is significant are not the changes to a particular swatch of color but how much density any of the CMYK dyes can lose before an image is deemed unacceptable based on ‘psychometrics evaluations’. As set by Wilhelm Imaging Research, currently allowed percentages of density loss before failure is reached runs from a low of 25% for Magenta to a high of 35% for Yellow.

Clearly this is a very different type of measurement than painters are accustomed to. When a particular ink system claims a specific duration for lightfastness, it is referring to how long it might take to reach this level of density loss.

In addition, lightfastness ratings for digital prints almost exclusively assume the prints are mounted behind glass, at 70° F and 60% Relative Humidity (RH), with display conditions of 450 lux for 12 hours per day. While ultimately not a matter of either system being better or worse, it does show the distinct concerns and traditions each medium brings to its field.

Increasing ink longevity has been a primary focus of the industry in the last few years and great advances have been made. Pigment ink systems in particular fade much more slowly today compared to ink systems produced just two years ago.

However, since the focus by manufacturers is based on systems of printer, ink and paper that they can control, once artists diverge from that system by creating their own substrates, the risk of fading can increase. For this reason, artwork incorporating prints should be protected from ultraviolet radiation by using either a GOLDEN Topcoat or Varnish. See the pages on Protecting Artwork.

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