Test Condition:

1. Printer: All inks tested with EPSON 1160 with the exception of UltraChrome inks which were tested in EPSON Photo 2200.

2. Paper: Hahnemuhle Photo Rag Paper

3. Lightfastness: Irradiation UV light (Xe) 10,000 KJ/m2 / 1000 hours

4. Measuring Instruments: X-Rite 938 Spectradensitometer / LMT 1210 Colorimeter

Remarks:

1. DeltaE value lower than 2 is acceptable as non-visible difference from color changing.

2. Optical Density (OD) decreased percentage of 5% is acceptable as non-visible difference.


RIT and Wilhelm Imaging
Research both use high dosage fluorescent lighting to predict how long an ink might last in low doses of fluorescent lighting. Their tests however, do not give any indication of how an ink would perform when exposed to gallery lighting and ambient or direct sunlight. Xenon testing, while being much more expensive to use, represents more realistically the full spectrum of light that inks are exposed to such as sunlight, incandescent, and fluorescent. The following tests were made with full-spectrum Xenon light at 1000 hours to better imitate the conditions in which prints fade (high levels of illumination). We also had the humidity varied because this is what affects prints in real life. Our motive was to show how advanced our inks are in side-by-side comparison to the competition so you can better determine why we are a premium quality product.

How the tests were performed.
All of the monochromatic inks were printed in patches of gray or black. The color inks were printed in patches of their full hue.They are dried down to determine their starting Optical Density (how dark) and their Spectral Information (what shade of color or hue they are). They are then put into a Xenon test chamber and continuously exposed for 1,000 hours. The humidity is not kept at a constant (friendly) rate, but is cycled to imitate varying humidity conditions (from 20%-90%). After the test was concluded, all of the ink specimen tests were re-measured to determine their resultant Optical Density and Spectral Information to arrive at density loss and color shift.

How to interpret these tests.
RIT and Wilhelm allow a density fade rate of 30% to arrive at their ratings endpoints. However, the threshold at which humans can detect fade is 5%. The deltaE figures represent a measurable difference in color. The threshold for humans is 2.

Conclusion:
We believe that side-by-side comparisons of actual fade (density decrease) and color shifting (deltaE differences) is the best way to determine how well an ink performs. PiezoTones have less than visible fade and color shifting in the same tests in which competing inks have high rates of fading. UltraChrome™ inks by EPSON® have been presented here as a comparison because so much attention is being paid to their performance tests and ratings of 34 to 150 years by Wilhelm Imaging Research. UltraChrome inks have fade rates from 4% - 17% in these Xenon tests. PiezoTone inks with Museum Black have fade rates from less than 1% to only 7.3%. The DeltaE differences in UltraChrome and PiezoTone inks are both very low.

Our opinion is that the 30% fade rate allowed by RIT and Wilhelm is too generous. While it makes for impressive ratings, it does not meet users expectations. Users constantly see that inks rated at 50 years and even 100 years are changing within months. What they are seeing is perceptible amounts of fade and color shifting. While Xenon tests do not attempt to indicate a number of years that one can expect, they do indicate a level of performance that one can expect. They are especially effective at looking at products in comparison. PiezoTones are designed to perform without perceptible fade and color shifting in equivalent tests which give greater than 100 year longevity ratings to inks which have perceptible amounts of fade.