Digital printing has matured.With the latest generation of pigment inks and printers, it is possible to produce a print whose quality can approach that of, dare I say it, dye transfer.
However, the digital work flow, starting with the digital capture or scan, continuing through manipulation and color management, leaves few choices when ready to print. Aside from print size, the only other real choice is what to print on. There are many papers to chose from, but for the most part, the differences are subtle. You can select a glossy, satin, or matte finishes, smooth or textured. There also are a few more unusual media such as canvas and transparency materials that can be used in a digital printer. What I call “tri-trans printing” (printing one color each on three or four transparencies) presents another method for producing a different look for your prints.
I came to this process indirectly. I’ve been interested in alternative photographic processes for a long time. I recall making salt and gum-dichromate “sun prints” following the instructions in the chemistry set that I had as a child. So I began tooling up and getting educated to start doing tri-color gum-dichromate printing. I found that I had a problem in producing grayscale transparencies because of the matte black K3 ink in my printer. It seems that the matte ink does not have the chemistry to allow it to adhere to transparency material. The ink would smudge and rub off on handling. At first I thought of lamination to protect each separation, but I feared this might result in less sharpness during contact printing due to the additional thickness. I then thought of using a protective photo spray but could not find one that did not include UV filtering. UV light is a necessary component for gum-dichromate printing, as it is this part of the spectrum that hardens the gum. Not wanting the expense of changing to the glossy ink, I next thought why not print another color? That led me to figure out how I could use Photoshop to make grayscale separations that were not gray—and how to maintain the pure colors used in dye-transfer printing.
In dye transfer, separations are made for the yellow, magenta, cyan, and black layers. A matrix is made from each of these separations, and used to carry a color dye, that is transferred to the print media in a manner similar to silk-screening. This is how Technicolor movies are made. By making grayscale separations and applying the correct color to each, it is possible to make a print that layers multiple transparencies in registration and reproduces the original color.
A good working profile is important to ensure that the primary colors will print as pure as possible, but making a printer profile for transparencies is a bit tricky. I use Monaco EZColor for profiling, and have both reflective and transmission ITT test targets. I tried various ways to make a transparency profile; the most workable method I found was to print the test patches onto transparency material, then attach the reflective target that the soft- ware uses for comparison. I placed the transparency on the scanner with a piece of bright white photo- grade paper on top (I used Moab Kayenta). I then scanned it all as a reflective source, and used it to produce the profile. Trying to scan as a transmission with the transmission target simply didn’t work due to the low densities inherent in the highlight colors.
With a working profile, we’re almost ready to make a print. Once your images is color balanced, burned and dodged, etc., you may want to enlarge the canvas a bit to add registration marks so that alignment is easier when stacking the transparencies.
When the image is ready, select Image > Mode > CMYK color. On the Channels pallet, right-click on and delete the black, yellow, and magenta channels leaving only cyan. Then select Image > Mode > Grayscale, followed by Image > Mode > Duotone, and select Monotone. With the color picker, select a pure cyan using the table shown below.
Close the dialog and save the image as a copy, adding a C to the file name to indicate it’s the cyan file. Now revert to the original and repeat the process for each of the other channels adding M, Y, and K to each file name respectively. Note that in each of the colors, the complementary is equal to zero, while the other two colors are at full saturation. The Black channel is already a grayscale image, so there’s no need to convert it to a monotone.
Each image is now printed using your transparency profile. The prints are then layered in registration on a light table, then float-mounted on a foam-core mounting board with a piece of the same Moab Kayenta behind them for reflective viewing. Transmission viewing works well also, with lighting from behind. Due to the low absorbency of transparency materials, there is a limit to the amount of ink that can be applied. Because each of the layers is printed at full density, the overall result is a transparency print with a higher saturation than can be achieved when printing all colors on a single piece of material.
In theory, the above method should result in a more or less perfect print. In practice—particularly in images with a dominant color—I’ve found that I sometimes need to reduce the Opacity setting of the dominant color to avoid a color cast.
The layers should be ordered by density, with the highest density on the bottom. In my experience, the order is: bottom is yellow; center is magenta; top is cyan (in my transparency prints, black goes on the bottom).
Allowing the prints to float means that they are not in tight contact with one another. As the viewing angle changes, slight changes in color occur due to chromatic aberration. This effect can be amplified by placing spacers between each of the layers when mounting. You can use clear Mylar or transparency material between the layers, or make a stack with each print attached to two- or four-ply matte board. Another option is to print the black layer (or any other layer) onto the white backing paper to create another effect.
I tend to work primarily in the landscape and find that florals work well with the tri-trans technique because it offers good color saturation. Architectural shots work well with this method as well. Portraiture can work, but you need to watch the color balance carefully to maintain flesh tones. White skies or images with a lot of white or very high-key colors don’t work well because very little ink is placed on any of the layers. Dark or low-key images work best without a black layer. Other than these technical issues, I don’t know of any reasons any given image should not be tri-trans printed.
The constraints of digital printing have brought us to a time when prints tend to look alike. There was a time when an educated eye could immediately tell if a color print was made using a negative or a positive process. Of course, content is the most important part of any photograph. The choice of printing method can enhance or subtract from the content. Tri-trans printing offers another choice for making the most of your images.