A complete darkroom workflow for printing 4×5 color slides onto RA-4 paper using a reversal process with black-and-white first development, controlled fogging, and precise color balancing.
Introduction — Why This Is Hard (and Mostly Lost)
Color photography was not always taken seriously. For decades, “serious” photography meant black and white, while color was often associated with advertising, postcards, and amateur snapshots. That perception began to change in the 1970s, notably after the 1976 exhibition of William Eggleston at the Museum of Modern Art in New York, which helped establish color as a fine art medium.
At the same time, the highest-quality color printing process ever developed — dye transfer — reached a level that, even today, is difficult to match. Printers like Ctein mastered this process to an extraordinary degree. Dye transfer prints offered unmatched control over color, density, and tonal separation. The richness of color and the subtlety in highlights are still astonishing.
I had the great opportunity to see one such print myself—although it was not on exhibition, the kindness of the Collection Manager made it accessible: a dye transfer print by Jorge Fick from a photograph by Eliot Porter, in the collection of the National Gallery of Art in Washington (Fig. 1). The quality is remarkable — especially in delicate highlight areas and subtle color transitions. It sets a benchmark that is very difficult to reach with modern materials.
Unfortunately, dye transfer is now essentially a lost process. Kodak, the sole manufacturer of dye transfer materials, discontinued production in the mid-1990s after roughly 60 years. As Ctein wrote at the time, only a handful of practitioners remained, many relying on stockpiled materials. He noted:
“I’d guess that there are maybe a dozen or so of us left in the world actively engaged in dye transfer printing. Most dye transfer printers simply gave up the medium.”
There were attempts to revive the process — for example, efforts by Dr. Jay Patterson and The Dye Transfer Company in Houston — but these materials never became widely available (Ctein). To this day, access to the necessary chemistry and matrix films remains extremely limited.
For photographers working today, especially amateurs like myself, dye transfer is not a realistic option. The materials are unavailable, the process is complex, and the knowledge is fading.
This is, in a sense, a loss. A remarkable printing technology — capable of extraordinary results — has effectively disappeared.
Historically, color transparencies could be printed in four principal ways: 1) directly onto reversal paper, most notability Cibachrome/Ilfochrome; 2) through dye transfer; 3) by means of an internegative, for example with Kodak Vericolor Internegative film; and, later, 4) through digital intermediate methods. If niche hybrids and proprietary variants are also counted, the number becomes larger, but these four routes cover most real-world practice. Today, however, the first three have either disappeared, become impractical, or remain accessible only to a very small number of specialists.
The question, then, is:
Can we still produce a direct optical color print from a transparency, in the darkroom, using materials that are still available?
The following is an attempt to answer that question.
Modern Workarounds — From Transparency to Print Today
Scan and inkjet print. The most common approach is straightforward: the slide is scanned at high resolution, color-corrected on a computer, and then printed using a high-end inkjet printer. This method is reliable, flexible, and capable of excellent results. It also allows full control over contrast, color balance, and local adjustments that would be extremely difficult to achieve in the darkroom.
Digital exposure onto RA-4 paper. A second option preserves the photographic paper look by combining digital input with RA-4 output. In this workflow, the scanned image is sent to a digital enlarger such as a Lambda or LightJet system, which exposes traditional RA-4 paper using RGB lasers and is then processed in standard RA-4 chemistry. The result is still a chromogenic print, but the exposure step is no longer optical.
Both approaches are effective and widely used. However, they share a common limitation: they break the purely analog chain. The image is no longer transferred directly from the original transparency to the final print through optical and chemical means.
For many applications, this is not a problem. But for those interested in maintaining a fully analog workflow—especially in large format—these solutions feel like a compromise. The question then remains whether a direct darkroom method, using currently available materials, is still possible.
For this test, I selected a 4×5 Velvia 50 slide of a flower (Fig. 2), whose vivid colors and strong contrast—from deep blacks to intense reds, greens, yellows, and bright white reflections—make it a demanding target for this process.
The B&W / RA-4 Reversal Method
Concept
RA-4 paper is a chromogenic material composed of silver-halide emulsion layers, each sensitized to different spectral regions and containing dye couplers. In normal RA-4 printing, exposure creates a latent image and color development reduces the exposed silver halide while forming dyes; the silver is later removed, leaving only the dye image.
In this method, a first black-and-white development converts the enlarger exposure from the transparency into a metallic silver image, consuming part of the available silver halide. This effectively blocks further development in those regions. The remaining undeveloped silver halide is then uniformly fogged with white light, creating a new latent image. During the subsequent RA-4 development, dyes form primarily in these newly exposed regions. Because the first development has already consumed silver halide mainly in the brighter areas of the projected slide, dye formation shifts toward the areas that initially received less exposure, reversing the tonal relationship and producing a positive image.
The process is not balanced by design. The first development controls how much silver halide remains available for dye formation: if too strong, highlights block and color becomes unstable; if too weak, density and blacks are insufficient. Fogging must also be carefully controlled: too little results in incomplete reversal, while too much produces dye formation across the entire image, leading to milky blacks and reduced contrast. Because the color layers are no longer operating under their intended conditions, color balance becomes non-intuitive and often shows a strong magenta bias.
Workflow
- Exposure. Project the 4×5 transparency onto RA-4 paper using the enlarger. Exposure times are short (typically a few seconds) and must be carefully controlled to avoid blocking highlights.
- First development (B&W).
Developer: Ilford Multigrade or HC-110 (Dilution B)
Time: ~40 s
Temperature: ~35 °C
This step defines the base density and contrast. - Stop bath.
Water rinse or stop bath
Time: ~30 s
Prevents carryover into the fogging step. - Fogging.
Uniform exposure to room light
Time: 5–10 s (typically ~5 s)
This activates the remaining silver halide and enables reversal. - RA-4 development.
Standard RA-4 developer
Time: ~45 s @ 35 °C
Builds the final dye image. - RA-4 blix and wash.
Blix: ~45 s
Followed by a standard wash.
Sensitivity and Testing
Stepwise calibration. The process was calibrated through a structured series of tests (Fig. 3a, 3b), systematically varying filtration (Y, M), exposure time, and fogging while keeping the overall workflow constant. Initial trials (T1–T4) (Fig. 3a) used standard RA-4-like filtration (e.g., Y50 / M40, Y50 / M25) and longer exposures (7.5–10 s), which resulted in strong magenta casts, purple backgrounds, and unstable blacks.
Magenta bias identification. Reducing magenta filtration alone (down to M15 and below) did not resolve the issue. In several cases, the color balance behaved non-linearly, with greens shifting incorrectly and backgrounds remaining tinted. This confirmed that the process introduces an intrinsic magenta bias rather than a simple filtration offset.
Exposure reduction. A key turning point was the progressive reduction of exposure time from ~10 s down to ~5 s and below. This significantly improved background neutrality and prevented highlight blocking. Overexposure was identified as a primary driver of the purple/magenta background.
Filtration asymmetry. Systematic tests (T6–T11) showed that increasing yellow filtration while keeping magenta very low was essential. The process converged toward a strongly asymmetric balance, with Y increasing from 50 → 70 → 90 → 100, while M was reduced to ~5.
Fogging control. Fogging was stabilized at ~5 s using indirect room light. Earlier tests with longer or more direct fogging produced milky blacks and reduced contrast. The combination of short fogging and reduced exposure defined a stable working regime.
Final working regime. The protocol converged to the following reproducible parameters (P1–P2):
Filtration: Y100 / M5
Exposure: ~3.2–3.5 s
First development: ~40 s (with tests down to ~35 s)
Fogging: ~5 s (indirect light)
RA-4 development: ~45 s @ 35 °C
Practical outcome. Under these conditions, the process becomes stable: blacks are neutral, greens render correctly, and reds remain saturated with acceptable highlight detail. Once this regime is reached, exposure controls density while filtration controls color, allowing consistent and predictable adjustments.
Results and Limitations
Figure 4 shows the final RA-4 reversal print, while Figure 2 presents a digitized version of the original 4×5 Velvia transparency. A comparison between the two shows that the method is able to recover much of the visual structure of the slide: deep dark tones are largely restored, greens are rendered convincingly, and the overall red-pink balance of the flower is preserved.
The most important result is that the print no longer appears as an unstable experiment. The strong magenta bias of the initial tests (Fig. 3a) was progressively removed, the background approached a convincing black (Fig. 3b), and the foliage regained a natural green rendering. In that sense, the process can be considered successful: a direct optical print from a color transparency onto RA-4 paper was achieved using currently available materials.
At the same time, the comparison with the original slide also shows the limitations of the process. The deepest blacks are nearly recovered, but not perfectly matched in all regions. More importantly, the highlights in the flower remain somewhat compressed, and some of the subtle tonal separation visible in the bright red and pink areas of the original transparency is reduced in the print.
The final result is therefore acceptable and, in practical terms, already highly encouraging. It demonstrates that the B&W / RA-4 reversal workflow is viable and controllable. However, it also confirms that further refinement is still possible, especially in preserving highlight detail and improving tonal separation in highly saturated red regions.
Limitations
The main limitation of the present workflow is the tendency to compress highlights. This is particularly visible in the bright petals of the flower, where the original slide retains more micro-detail and smoother tonal transitions than the final print.
Although the background black was substantially improved, some shadow regions still differ slightly from the density and neutrality seen in the original transparency. This suggests that the process is close to, but not yet fully at, its maximum tonal performance.
Additional improvements may be possible through slightly shorter exposure, modest reduction of first-development time, or more controlled fogging geometry. These refinements were not fully explored here, but the current results suggest that the method has further potential.
Conclusion
This experiment shows that a direct optical print from a color transparency onto RA-4 paper is still possible using currently available materials. Although the process is not natively designed for reversal and requires careful calibration, stable and visually convincing results can be achieved.
The method remains sensitive and does not fully match the tonal richness of the original slide, particularly in highlight regions. However, the recovery of deep blacks, natural greens, and overall color balance demonstrates that this hybrid B&W / RA-4 approach is more than a curiosity—it is a viable darkroom technique.
With further refinement, especially in highlight control, the process could be improved even further. More importantly, it offers a meaningful way to reconnect with a fully analog workflow that has largely disappeared.
