25 January 2012

Black and White with Ultrachrome K3 Inks: Fade Tests for Three Workflows

Introduction

I have used Ultrachrome K3 inks for my black and white printing since 2009. Initially, when I first had a K3 printer, I carried on with the Quadtone Rip workflow, because I was used to it from the previous generation of Ultrachrome inks (which required it for neutral monochrome prints) and it worked for me. Since then, I've used Epson's Advanced Black and White mode (found in the printer driver) and have trialed using the colour driver with colour profiles made with Datacolor's Spyder3 Print Extended Grays profiling targets.

One reason to stick with the QTR workflow is that it uses the least coloured ink of the three workflows to produce black and white prints; Epson's Advanced Black and White mode uses slightly more colour than QTR and the colour driver uses slightly more coloured ink again.

The advantage of using the Epson colour driver is that it is fully colour-managed. In QTR or Advanced Black and White, only luminance can be colour-managed (via an icc profile produced by the QTR-Create-ICC application). The more fiddly part is that getting a neutral hue on different papers requires careful examination of test prints, then making adjustments and more test prints (and getting a bit neurotic in the process). With the Epson colour driver and Datacolor's Spyder3 Print Extended Grays profiling targets, however, the job of getting a dead neutral print is done for us, as the workflow is completely profile-managed. One can also add profile-managed spit-tones if one wishes.

I have made a comparison fade test to see how stability compares between the three workflows.

Method

21-Step graded test strips were printed (using photo black ink) on the same sheet of resin-coated paper, as follows:
1. Epson Colour Driver, profiled with Datacolor's Spyder3 Print Extended Grays targets.
2. Epson Driver, via the Advanced Black and White mode.
3. Quadtone Rip.

I printed two copies. One was stored in a drawer and the other was taped to the inside of in a sunlit north-facing New Zealand window. The location is not perfect, because of trees, which block the direct sun for at least half the day; but it's in the hottest part of the day that the print gets direct sun. I estimate that the print gets direct sun for at least at third of the day.

New Zealand has higher levels of UV than many other locations. An explanation and video are featured on the NZ Science Learning Website. To summarise:

1. The closest the sun gets to the earth is during December/January (the Southern Hemisphere summer), because the earth travels in an ellipse. This adds 7% to the UV levels found in summer in the Northern Hemisphere, at the same latitudes.
2. There is less ozone in the Southern Hemisphere – which adds another 10% to our UV radiation.
3. We have relatively clean air, which adds another 20% to our UV radiation.