Alternative Processes—A Sustainability Overview

Part 11 of 13 in the Sustainable Darkroom series | ← Previous: Part 10 | Next: Part 12 →

The silver gelatin process dominates this series because it dominates my practice. But there's a whole world of alternative photographic processes—some predating silver gelatin, some developed alongside it, some genuinely more sustainable.

This isn't a comprehensive guide to any of these processes. I've done some cyanotype work in the past; I may explore others in the future. For now, this is a survey: what are the main alternative processes, and how do they compare environmentally to silver-based photography?

The answers range from “genuinely the most sustainable photographic process possible” to “actually worse than you'd think.”

The Spectrum of Sustainability

Alternative processes fall roughly into three categories:

Iron-based processes (cyanotype, Van Dyke brown, kallitype, platinum/palladium): Use iron salts as the light-sensitive component. Some also use silver or noble metals.

Plant-based processes (anthotype, chlorophyll printing): Use photosensitive compounds from plants. No metals or synthetic chemicals.

Other processes (gum bichromate, carbon, collodion): Various chemistries with varying environmental profiles.

Let me work through the major ones.

---

Cyanotype: The Benchmark for Sustainable Printing

Chemistry: Ferric ammonium citrate + potassium ferricyanide

The process: Mix the two solutions, coat paper, dry, expose to UV light (sunlight works), wash in water. The exposed areas turn Prussian blue; the unexposed areas wash away.

Environmental profile:

Cyanotype is remarkably benign:

• Ferric ammonium citrate: An iron compound used in food supplements. Non-toxic. The “green” form is slightly more light-sensitive than the “brown” form.

• Potassium ferricyanide: Despite the alarming name, this is not a cyanide hazard under normal conditions. The cyanide groups are tightly bound to iron and won't release as hydrogen cyanide unless heated above 300°C or exposed to strong acids (neither of which happens in cyanotype).¹

• Processing: Plain water. No fixer, no developer, no stop bath. The unexposed chemistry simply washes away.

• Waste: Water containing small amounts of iron compounds. Essentially harmless to aquatic systems at the concentrations involved in home printing.

Honest concerns:

• The “new cyanotype” process (Mike Ware's formulation) sometimes uses dichromate as a contrast control agent. Dichromates are carcinogenic and toxic. If you're using new cyanotype, check whether your formulation includes dichromate.

• Potassium ferricyanide will stain everything blue. Not toxic, but annoying.

Assessment: Classic cyanotype is probably the most environmentally sustainable photographic printing process available. No silver, no toxic metals, no hazardous waste, water-only processing. If sustainability is your primary concern, cyanotype is the answer.

My experience: I've made cyanotypes in the past—it's a lovely process for contact printing and photograms. The blue is distinctive, the chemistry is forgiving, and I never worried about disposal because there's nothing to worry about.

---

Anthotype: The Ultimate Sustainable Process

Chemistry: Crushed plant material (flower petals, berries, leaves)

The process: Extract pigment from plants, coat paper, dry, expose to UV light for days or weeks. The exposed areas bleach; the protected areas retain colour.

Environmental profile:

Anthotype has essentially zero environmental impact:

• Chemistry: Plant juice. Literally blended flowers and water (or alcohol as a solvent).
• Processing: None required. The image forms by bleaching.
• Waste: Vegetable matter and water.
• Permanence: Here's the catch—anthotypes are not permanent. The image will continue to fade with any light exposure. They cannot be fixed.

Honest concerns:

• Impermanence: Anthotypes fade. Period. Display them and they disappear. Store them in the dark and they last longer, but they're fundamentally fugitive images.

• Exposure times: Days to weeks of direct sunlight. This is not a quick process.

• Reproducibility: Each plant, each season, each batch gives different results. This is either charming or frustrating depending on your temperament.

Assessment: Anthotype is the most sustainable photographic process possible—your materials are garden waste and sunlight. But the impermanence means it's more an art/craft practice than a archival photographic process. The aesthetic is unique and beautiful; the practical limitations are significant.

My interest: I haven't tried anthotypes yet, but the sustainability angle is compelling. The exposure times (potentially weeks) make it difficult to integrate into regular practice, but as a summer project with genuinely zero environmental guilt, it's appealing.

---

Van Dyke Brown: Sustainability Compromised

Chemistry: Ferric ammonium citrate + tartaric acid + silver nitrate

The process: Similar to cyanotype—coat, dry, expose to UV, develop in water, fix in weak sodium thiosulfate.

Environmental profile:

Van Dyke brown is less sustainable than cyanotype because it reintroduces silver:

• Silver nitrate: A silver compound. The same silver concerns from gelatin silver processes apply here, though at lower concentrations per print.

• Processing: Requires a fixer bath (sodium thiosulfate), which will contain silver after use. Silver recovery applies.

• Handling: Silver nitrate is caustic and will burn skin. More hazardous to handle than cyanotype chemistry.

Honest concerns:

• Silver waste: The fixer contains dissolved silver. Less per print than gelatin silver, but not zero.

• Archival quality: Historically, Van Dyke prints had a reputation for fading. Modern practice with proper fixing and washing produces more stable results, but it's not as archival as platinum or properly processed silver gelatin.

• Silver nitrate handling: Requires gloves and eye protection. Stains skin brown (permanently, until the skin sloughs off).

Assessment: Van Dyke brown is a middle ground—more sustainable than gelatin silver (less silver per print, simpler chemistry) but less sustainable than cyanotype (silver is still involved). The aesthetic is beautiful (warm brown tones), but if pure sustainability is your goal, cyanotype is better.

---

Kallitype: Van Dyke's More Archival Cousin

Chemistry: Ferric oxalate + silver nitrate (developed in various solutions including sodium citrate, potassium oxalate, or others)

The process: Similar to Van Dyke brown—coat, dry, expose to UV, develop, fix, wash. The key difference is that kallitype uses ferric oxalate rather than ferric ammonium citrate, and offers more control over image colour through developer choice.

Environmental profile:

Kallitype shares Van Dyke's silver concerns:

• Silver nitrate: Same handling and environmental concerns as Van Dyke. Caustic, requires gloves and eye protection.

• Ferric oxalate: An iron compound. Mildly toxic if ingested but not a serious environmental concern at printing volumes.

• Processing: Requires fixer (sodium thiosulfate), which will contain silver. Silver recovery applies.

Honest concerns:

• Silver waste: Same as Van Dyke—fixer contains dissolved silver.

• More archival than Van Dyke: With proper processing (particularly thorough fixing and clearing), kallitype produces more stable prints than Van Dyke brown. The extra processing steps are worth it if archival quality matters.

• More complex: More chemistry options mean more variables. This is either creative freedom or unnecessary complexity depending on your perspective.

Assessment: Kallitype sits alongside Van Dyke brown in environmental terms—both use silver, both require silver recovery, both are more sustainable than gelatin silver on a per-print basis but less sustainable than cyanotype. The choice between them is aesthetic and archival rather than environmental.

---

Platinum/Palladium: Economically Absurd, Environmentally Benign

Chemistry: Ferric oxalate + platinum or palladium chloride

The process: Coat, dry, expose to UV, develop in potassium oxalate, clear in dilute acid, wash in water.

Environmental profile:

Platinum and palladium are noble metals—chemically inert and non-toxic:

• Platinum/palladium salts: Expensive but not environmentally hazardous. These metals don't bioaccumulate or cause aquatic toxicity at the concentrations involved.

• Ferric oxalate: An iron compound. Essentially benign.

• Developer (potassium oxalate): Mildly toxic but not a serious environmental concern at printing volumes.

• Clearing bath (citric acid or dilute HCl): Acids require neutralization before disposal but aren't environmentally persistent.

Honest concerns:

• Cost: Platinum is approximately €30–40 per gram. A single 8×10 print might use €10–20 worth of platinum. This is economically prohibitive for most practitioners.

• Palladium alternative: Palladium is cheaper (roughly half the cost of platinum) and produces similar results. Still expensive.

• Resource extraction: Platinum group metals are mined, with associated environmental impacts. But the quantities used in photography are negligible compared to industrial uses (catalytic converters, electronics).

Assessment: Platinum/palladium printing is environmentally benign—the chemistry is non-toxic, the metals are inert, the waste is minimal. The barrier is economic, not environmental. If you can afford it, it's one of the more sustainable printing processes available.

---

Gum Bichromate: The Dichromate Problem

Chemistry: Gum arabic + pigment + ammonium or potassium dichromate

The process: Coat paper with gum/pigment/dichromate mixture, expose to UV, develop in water. Multiple coats can build up density and colour.

Environmental profile:

Gum bichromate has a significant environmental concern:

• Dichromates (ammonium dichromate, potassium dichromate): These are carcinogenic (Group 1 carcinogen—causes cancer in humans), toxic, and environmentally hazardous. They require careful handling, proper disposal as hazardous waste, and should not be washed down the drain.²

• Gum arabic: A natural tree sap. Completely benign.

• Pigments: Varies. Some pigments contain heavy metals (cadmium yellows, lead whites); modern pigments are often safer.

Honest concerns:

• Health hazard: Dichromates are genuinely dangerous. Repeated exposure causes sensitization, skin ulceration, respiratory damage, and cancer. This is not hypothetical—it's documented.

• Environmental hazard: Chromium compounds are toxic to aquatic life and environmentally persistent. Hexavalent chromium (which dichromates contain) is particularly problematic.

• Alternative sensitizers: Some practitioners have explored dichromate-free gum printing, but results are generally inferior.

Assessment: Gum bichromate produces beautiful, painterly prints—but the dichromate requirement makes it environmentally and personally hazardous. I don't practice this process, and the sustainability concerns are a significant reason why. If you do practice it, treat dichromates with extreme respect: gloves, ventilation, proper disposal, and awareness of the health risks.

---

Summary Table

Process	Primary chemistry	Toxicity	Silver involved	Waste disposal	Overall sustainability
Cyanotype	Iron salts	Very low	No	Drain-safe	Excellent
Anthotype	Plant pigments	None	No	Compostable	Excellent (but impermanent)
Van Dyke brown	Iron + silver nitrate	Moderate	Yes	Silver recovery needed	Moderate
Platinum/palladium	Iron + noble metals	Low	No	Drain-safe (after neutralization)	Good (but expensive)
Gum bichromate	Dichromate	High	No	Hazardous waste	Poor
Kallitype	Iron + silver	Moderate	Yes	Silver recovery needed	Moderate

---

My Experience and Interest

This overview is reconnaissance, not deep experience. My practice is primarily silver gelatin.

What I've done:

• Cyanotype: I've made cyanotypes—contact printing and photograms. The process is straightforward, the sustainability is excellent, and the distinctive blue works for certain kinds of images.

What I haven't explored:

Most of these processes remain unexplored. My practice has been focused on silver gelatin work, and that's where my time goes. Alternative processes aren't incompatible with what I do—they just haven't made it to the top of the list yet.

The sustainability profiles are useful context: cyanotype and anthotype have the most straightforward environmental stories. The silver-based alternatives (Van Dyke, kallitype) would require the same silver recovery attention I already apply to gelatin silver. Gum bichromate's dichromate concerns put it at the bottom of my interest list.

---

A Note on “Historical” vs. “Sustainable”

There's a tendency to assume that older, historical processes are more sustainable than modern ones. This isn't necessarily true.

Historical processes that are genuinely sustainable:

• Cyanotype (1842)
• Anthotype (1842)
• Salt prints (with proper silver recovery)

Historical processes that are environmentally problematic:

• Daguerreotype (mercury vapour—extremely toxic)
• Collodion wet plate (ether, cadmium, silver nitrate)
• Uranium toning (radioactive)
• Mercury intensification (highly toxic)

And some modern processes are quite sustainable:

• Inkjet printing (no wet chemistry, though there are ink and cartridge waste concerns)
• Dye sublimation (minimal chemistry)

The lesson: evaluate each process on its actual chemistry, not its historical pedigree.

---

References