Sustainable Darkroom Practices
A Practical Guide
Introduction
This guide is for darkroom photographers who want to minimise their environmental impact without sacrificing the quality of their work or the pleasure of the process.
The advice here is practical, not theoretical. It's based on what actually matters—quantified where possible, honest about trade-offs, and focused on actions that make a real difference rather than gestures that feel good but accomplish little.
The core finding from extensive research into photographic chemistry and environmental toxicology is simple: silver dominates everything else. The dissolved silver in your spent fixer represents approximately 80% of your darkroom's environmental burden. Address that, and you've addressed most of the problem. Ignore it, and nothing else you do matters much.
This doesn't mean other practices are irrelevant. Water efficiency, proper disposal of hazardous chemistry, and thoughtful process choices all contribute. But they're refinements on top of the fundamental requirement: you must deal with the silver.
The good news is that dealing with silver is cheap, simple, and actually saves money in the long run. The methods in this guide require minimal investment and integrate easily into existing workflows.
The goal isn't environmental perfection—it's proportionality. Address the big things first. Be thoughtful about the rest. Continue making photographs.
The Hierarchy of Impact
Understanding relative impact prevents wasted effort. Not all environmental concerns are equal.
| Priority | Action | Share of Impact |
|---|---|---|
| 1 | Silver recovery from fixer | ~80% |
| 2 | Efficient washing | ~10% |
| 3 | Proper hazardous waste disposal | ~5% |
| 4 | Chemistry choices, packaging, energy | ~5% |
What this means in practice:
If you recover silver from your fixer and wash efficiently, you've addressed approximately 90% of your darkroom's environmental impact. The remaining choices—which developer to use, whether to buy concentrates, how to handle packaging—matter, but they're minor compared to the first two items.
Conversely, if you're meticulous about developer choice and packaging recycling but pour fixer down the drain, you've optimised the wrong 10% while ignoring the 80% that actually matters.
Address the hierarchy in order. Don't skip ahead to refinements until the fundamentals are in place.
Silver Recovery
Why It's Non-Negotiable
When you fix film or paper, unexposed silver halides dissolve into your fixer as silver thiosulfate complexes. This silver accumulates with every roll or print processed.
The concentrations are substantial:
- Spent fixer typically contains 3,000–8,000 mg/L dissolved silver
- A single litre of exhausted fixer may contain 5–8 grams of silver
- Home darkrooms easily generate several grams of dissolved silver per month
The toxicity is severe:
- Aquatic invertebrates (the base of freshwater food webs) die at 0.6 μg/L
- Your spent fixer exceeds this threshold by a factor of roughly ten million
- Silver is a persistent heavy metal—it doesn't biodegrade or break down
Without recovery, every session releases heavy metal contamination into the environment. This isn't hypothetical harm—it's measurable, documented toxicity at concentrations far exceeding safe levels.
Steel Wool Method
The simplest recovery method, suitable for any home darkroom volume. Costs pennies, removes 95–99% of silver.
The chemistry: Iron is more reactive than silver. When steel wool contacts silver-laden fixer, iron atoms donate electrons to silver ions, reducing them to metallic silver while the iron dissolves.
2 Ag⁺ + Fe⁰ → 2 Ag⁰ + Fe²⁺
The silver plates onto the steel wool surface as grey-black sludge, eventually falling to the container bottom as the wool dissolves.
Materials Needed
- 5-litre plastic container with loose-fitting lid (milk jug, chemical container)
- Fine steel wool, grade 0000 or 000 (~50g per batch)
- Well-ventilated outdoor location
- Rubber gloves
- Stirring stick (wood or plastic)
- Silver test strips or potassium chromate solution (optional but recommended)
- Coffee filters and funnel for final separation
- Labelled container for silver sludge collection
Procedure
Step 1: Collect fixer
Accumulate spent fixer in your collection container until nearly full. Label clearly: “SPENT FIXER – CONTAINS SILVER – DO NOT DRAIN.”
Keep B&W fixer and colour blix separate if possible—they have different chemistries and recovery may be more efficient when separated. However, mixing them won't prevent recovery; it just complicates the chemistry slightly.
Step 2: Prepare steel wool
Wearing gloves, pull apart approximately 50g of fine steel wool. Fluff it loosely—don't compress into a tight ball. Surface area drives the reaction rate; more surface means faster, more complete recovery.
Step 3: Add steel wool to fixer
Take the container outdoors. Add steel wool to fixer, pushing gently so the wool is submerged. Replace lid loosely—gas must be able to escape.
Step 4: Daily maintenance
For 5–7 days:
- Visit the container outdoors
- Stir gently with a stick for 15–30 seconds
- Push any floating wool back under the surface
- Replace lid loosely
What you'll observe:
- Days 1–2: Steel wool darkens; solution may become cloudy
- Days 3–5: Grey-black sludge accumulates at bottom; wool visibly dissolving
- Days 5–7: Most wool dissolved; heavy black precipitate; solution greenish-yellow (iron compounds)
Step 5: Test for completion
Before disposing of the liquid, verify silver removal:
Hypo check solution: Add a few drops to a small sample. Clear or light yellow = silver depleted. Milky precipitate = continue treatment.
Visual assessment (less reliable): Solution should be greenish-yellow from iron compounds, with no milky cloudiness. Steel wool should be mostly or fully dissolved.
If silver remains, add more steel wool and continue for another 3–5 days.
Step 6: Separate and dispose
Once silver is depleted:
- Set up funnel with coffee filter over clean container
- Carefully decant liquid through filter
- The filtered liquid is now drain-safe (contains iron but no significant silver)
- Silver sludge remains on filter and in original container
- Rinse remaining sludge from container through filter
- Allow filter to dry completely (24–48 hours)
- Transfer dried sludge to labelled collection container
Step 7: Accumulate and dispose of sludge
The silver sludge is approximately 20–30% silver by weight, mixed with iron compounds and other precipitates. Options:
- Sell to refiner: Need significant quantity (100g+ sludge) to be worthwhile
- Hazardous waste collection: Concentrated solid is easier to handle than litres of liquid
- Store until quantity justifies action: Sludge is stable; no urgency
Safety Notes
Hydrogen sulfide (H₂S): The reaction produces this toxic gas (rotten egg smell). Always work outdoors. Never seal the container completely. If you smell strong H₂S indoors, ventilate immediately.
Spent fixer: Corrosive. Wear gloves when handling. Avoid skin and eye contact.
Steel wool: Flammable when dry and finely divided. Store away from heat sources.
Electrolytic Recovery
For community darkrooms or high-volume users processing more than 100 litres per month, electrolytic recovery becomes practical.
How it works: Electric current passes through spent fixer. Silver ions migrate to the cathode and plate out as pure metallic silver. The fixer can then be reused or disposed safely.
Advantages:
- Produces high-purity silver (95–99.99%)
- Continuous operation possible
- Recovered silver has commercial value
- Can regenerate fixer for reuse
Disadvantages:
- Equipment cost: €500–2,000+
- Requires power supply and monitoring
- Generates chlorine gas at anode (ventilation critical)
- Not cost-effective at home darkroom volumes
Best for: Shared darkrooms, photography programmes, anyone processing enough volume to justify the investment.
Professional Collection
If DIY recovery isn't practical for your situation:
- Photo labs: Many accept spent fixer for their own recovery systems. Ask local labs.
- Hazardous waste collection: Municipal facilities accept silver-bearing waste. Check local schedules.
- Commercial pickup: Licensed hazardous waste handlers will collect from businesses; may serve serious hobbyists.
The key is that silver-laden fixer must go somewhere responsible—never down the drain.
Two-Bath Fixing
Two-bath fixing is a simple technique that extends fixer capacity 4–10× while ensuring archival quality. It works for both film and paper.
How It Works
Instead of one fixer bath, you maintain two in sequence:
┌─────────────────┐ ┌─────────────────┐
│ FIRST BATH │ → │ SECOND BATH │
│ (older) │ │ (fresher) │
│ │ │ │
│ Film/prints │ │ Ensures │
│ enter here │ │ complete fix │
│ │ │ │
│ Brief fix: │ │ Full time: │
│ 30-60 sec │ │ 2-4 min │
└─────────────────┘ └─────────────────┘
The logic: The first bath does most of the work, rapidly dissolving silver halides. It accumulates silver quickly and exhausts faster. The second bath (fresher, lower silver content) ensures complete fixing even as the first bath degrades.
When the first bath is exhausted, you don't discard both baths. You:
- Remove the first bath for silver recovery
- Promote the second bath to first position
- Make a fresh second bath
This rotation means you always have a nearly-fresh bath ensuring complete fixing, while the working bath that accumulates most of the silver can be pushed further before disposal.
Benefits
Extended capacity: 4–10× more film or prints per total volume of fixer consumed.
Archival assurance: Even if the first bath is marginal, the fresh second bath completes the job. You're never relying on exhausted fixer alone.
Better silver recovery: The first bath reaches higher silver concentrations, making recovery more efficient.
Cost savings: Less fixer purchased over time.
Fixing Times
| Material | First Bath | Second Bath |
|---|---|---|
| Most B&W films | 30–60 sec | 2–4 min |
| T-grain films (T-Max, Delta) | 45–60 sec | 3–5 min |
| RC paper | 30 sec | 1 min |
| FB paper | 30–60 sec | 2–3 min |
The first bath time is brief—just enough to begin the process. Don't skip it or rush it, but don't overdo it either. The second bath does the thorough work.
Rotation Procedure
When testing indicates the first bath is exhausted:
- Remove first bath to your silver recovery container
- Relabel: Second bath becomes first bath
- Mix fresh fixer for the new second bath
- Update your log with date of rotation
Don't wait until fixing fails. Test regularly and rotate proactively.
Testing Your Fixer
The goal is to rotate before the first bath fails, not after. Test before each session or at minimum every 10 rolls / 20 prints.
Hypo Check Method
Commercial hypo check solution (or DIY potassium iodide solution):
- Take small sample of fixer (~10ml)
- Add 2–3 drops of hypo check
- Observe result:
| Result | Meaning | Action |
|---|---|---|
| Clear or light yellow | Low silver, fixer good | Continue using |
| Slight cloudiness | Moderate silver | Monitor closely |
| Milky precipitate | High silver, near exhaustion | Rotate baths |
Clearing Time Method
- Cut a small piece of unexposed film leader
- Drop into fixer, start timer
- Note time for film to clear completely
| Result | Meaning | Action |
|---|---|---|
| Normal time (30–60 sec for rapid fixer) | Fixer good | Continue |
| 1.5–2× normal | Fixer marginal | Test more frequently |
| >2× normal | Fixer exhausted | Rotate baths |
Capacity Estimates
These are starting points—always verify by testing.
| Material | First Bath Capacity | Second Bath | Total System |
|---|---|---|---|
| 35mm film (36 exp) | 20–30 rolls | 40–60 rolls | 60–90 rolls |
| 120 film | 15–20 rolls | 30–40 rolls | 45–60 rolls |
| 8×10 RC paper | 40–60 prints | 80–120 prints | 120–180 prints |
| 8×10 FB paper | 30–40 prints | 60–80 prints | 90–120 prints |
Higher silver content materials (fast films, fibre paper) exhaust fixer faster. Adjust expectations accordingly.
Efficient Washing
Understanding the Physics
Washing removes residual fixer (thiosulfate) from film and paper. Incomplete washing causes long-term image degradation—yellowing, staining, density loss—that becomes visible over years and cannot be reversed.
The key insight: Washing is diffusion-limited, not flow-limited.
Thiosulfate ions must diffuse out of the emulsion (and paper base, for fibre prints) into the surrounding water. This diffusion is driven by the concentration gradient—the difference between thiosulfate concentration in the material versus the water.
When you first put fixed material into fresh water, the gradient is steep and diffusion is rapid. As the surrounding water accumulates thiosulfate, the gradient decreases and diffusion slows. Eventually, equilibrium is reached and diffusion stops—no matter how long you wait.
Continuous running water works by constantly replacing thiosulfate-laden water with fresh water, maintaining the gradient. But this is inefficient: most of the water does nothing useful; you're diluting already-clean water while waiting for diffusion.
Sequential water changes are more efficient: each fresh fill re-establishes the maximum gradient. Drain completely, refill with fresh water, agitate to disrupt the boundary layer, repeat.
Film Washing: The Ilford Method
Developed from research by Ilford, this method achieves archival washing with ~2 litres per roll.
| Step | Action | Time |
|---|---|---|
| 1 | Fill tank with fresh water | — |
| Invert 5 times | ~30 sec | |
| Drain completely | — | |
| 2 | Fill tank with fresh water | — |
| Invert 10 times | ~45 sec | |
| Drain completely | — | |
| 3 | Fill tank with fresh water | — |
| Invert 20 times | ~60 sec | |
| Drain completely | — | |
| 4 | Final rinse with wetting agent | ~30 sec |
| Hang to dry | — |
Total water: ~1.5–2 litres Total time: ~4 minutes Archival quality: Meets ISO 18917 standards
Why 5-10-20?
Each cycle removes roughly half the remaining thiosulfate. The increasing inversions compensate:
- Cycle 1: Lots of thiosulfate to remove; 5 inversions sufficient
- Cycle 2: Less thiosulfate; need more agitation to maintain removal rate
- Cycle 3: Even less; 20 inversions ensure thorough removal
After three cycles: ~87.5% of thiosulfate removed—sufficient for archival permanence.
Temperature
Match wash water temperature to processing temperature (typically 20°C). Cold water (<15°C) significantly slows diffusion. Warm water (>25°C) risks reticulation.
For Rotary Drums
Same principle, adapted for continuous rotation:
| Step | Action | Time |
|---|---|---|
| 1 | Fill drum, rotate continuously | 1 min |
| Drain completely | — | |
| 2 | Fill drum, rotate continuously | 1 min |
| Drain completely | — | |
| 3 | Fill drum, rotate continuously | 1 min |
| Drain completely | — | |
| 4 | Wetting agent rinse | 30 sec |
Print Washing: RC Paper
Resin-coated paper has a plastic layer that prevents fixer absorption into the paper base. Thiosulfate stays in the thin emulsion layer and washes out quickly.
Method: 2 minutes of gentle running water, or 3 tray changes (30 seconds each) with agitation.
Total water: 3–6 litres per session.
Critical: Do not overwash RC paper. Extended washing (>5 minutes) can cause water to penetrate the resin coating at edges, leading to curl and delamination. More washing doesn't improve archival quality—it risks damage.
Print Washing: Fibre Paper
Fibre paper is more demanding. The paper base absorbs fixer, creating a longer diffusion path. Traditional continuous-flow washing takes 30–60 minutes and uses 40–60+ litres.
The HCA Method (Recommended)
Hypo Clearing Agent (washing aid) dramatically accelerates thiosulfate removal through ion exchange. Sulfite ions displace thiosulfate ions, which are then more easily washed away.
| Step | Action | Time |
|---|---|---|
| 1 | Rinse in running water or 2 tray changes | 2–5 min |
| 2 | HCA bath with intermittent agitation | 10 min |
| 3 | Final wash: 3 tray fills, agitate 2 min each, drain completely between | 6 min |
Total time: ~20 minutes Total water: ~10–15 litres Savings: 70–80% water reduction vs. traditional method
DIY Hypo Clearing Agent
Commercial products work well, but HCA is trivially cheap to make:
Sodium sulfite 20–30g (food-grade is fine)
Table salt 2–3 teaspoons (optional; accelerates ion exchange)
Water 1 litre
Cost: ~€0.10 per litre vs. ~€0.50 for commercial products. Shelf life: 6 months in a sealed bottle. Discard when solution turns yellow (oxidation). Usage: Identical to commercial HCA.
Sequential Tray Method
For maximum efficiency after HCA:
- Fill tray with fresh water
- Agitate prints for 2 minutes (shuffle through stack, flip prints)
- Drain completely—lift tray, let all water run off
- Repeat twice more (3 fills total)
Each complete drain re-establishes the concentration gradient. Partial drains or overflow methods are less efficient.
Testing Your Wash
Verify periodically that your method achieves archival results.
Residual hypo test:
- Apply a drop of test solution to the print margin (unexposed white border)
- Wait 2 minutes
- Blot dry and examine
| Result | Meaning |
|---|---|
| No visible stain | Archival quality ✓ |
| Faint cream tint | Acceptable for display prints |
| Yellow or brown stain | Inadequate washing; continue or adjust method |
Commercial test solutions are available, or make your own with sodium sulfide solution.
Colour Processing
Colour processing (C-41 film, RA-4 prints) introduces additional environmental concerns beyond black-and-white work.
C-41 Film Development
Additional Concerns
CD-4 developer: The colour developing agent is a para-phenylenediamine derivative—the same chemical family that causes allergic reactions to hair dye. It's a skin sensitiser (wear gloves) and classified as harmful to aquatic organisms with long-lasting effects (H412).
EDTA in bleach: The ferric EDTA bleach contains ethylenediaminetetraacetic acid, one of the most persistent anthropogenic compounds found in surface waters. It's not readily biodegradable and can mobilise heavy metals from sediments.
Silver: C-41 bleaches out all the developed silver (the image is formed by dyes, not silver). 100% of the film's silver content ends up in the blix or fixer—typically 1–2g per roll.
Temperature sensitivity: C-41 requires 38°C ± 0.3°C. Failed batches from temperature drift waste chemistry and produce nothing usable.
Recommendations
Consider lab processing. Commercial labs have:
- Replenishment systems that use far less chemistry per roll
- Industrial silver recovery (electrolytic or metallic replacement)
- Automated temperature control (fewer failed batches)
- Economies of scale
For C-41 specifically, lab processing is often more sustainable than home processing—especially if you're processing one or two rolls at a time rather than batching.
If processing at home:
-
Batch your rolls. Chemistry oxidises quickly once mixed. Process 4–8 rolls per session rather than one at a time.
-
Choose your kit wisely. Kits with separate bleach and fix (rather than combined blix) allow you to recover silver from the fix using standard methods. The fix behaves like B&W fixer.
-
Collect all chemistry. Developer, bleach, blix—all should go to hazardous waste collection. Only wash water is drain-safe.
-
Wear gloves. CD-4 sensitisation is cumulative. Protect yourself.
-
Control temperature precisely. Failed batches waste everything.
RA-4 Colour Printing
The Silver Issue
RA-4 has a worse silver profile than B&W printing:
- B&W printing: ~60% of paper silver goes to fixer; ~40% stays in the image
- RA-4 printing: 100% of paper silver goes to blix (silver is bleached out; only dyes remain)
Colour paper has lower silver content per unit area than B&W paper, which partially compensates—but you're still sending all of it to waste.
Recommendations
Use drum processing. Rotary drums use approximately 1/10th the chemistry of tray processing. Over a year of printing, the difference is substantial.
Consider hybrid workflows. Scan negatives at home, send files to a commercial RA-4 printer (Frontier, Noritsu). Commercial machines run replenishment systems with systematic silver recovery—often more sustainable than home wet printing.
Collect all blix. Same silver recovery considerations as fixer. Blix-based kits complicate steel wool recovery (iron already present), but collection for hazardous waste disposal remains essential.
Experimental Processes
Lith Printing
Lith printing has a surprisingly favourable environmental profile. The extreme dilution (1+20 or more) means less developing agent per print than standard methods.
| Developer | Working Dilution | Hydroquinone per 8×10 |
|---|---|---|
| Standard MQ (1+9) | ~1.5 g/L | ~150 mg |
| Lith (1+20) | ~1.0 g/L | ~100 mg |
Lith uses 30–40% less hydroquinone per print than conventional development.
The long development times (6–15 minutes) don't change this—dilution dominates.
Fixer: Standard. Two-bath system, silver recovery, all the same practices apply.
Caveat: Lith printing's irreproducibility may increase paper waste. The process rewards accepting variation rather than chasing identical results.
Toning
Toning chemistry varies significantly in environmental profile:
| Toner | Handling | Disposal | Notes |
|---|---|---|---|
| Selenium | Gloves essential | Hazardous waste | Replenish rather than discard; lasts years |
| Sepia/sulfide | Ventilate (H₂S) | Drain-safe (diluted) | The smell is the main issue |
| Gold | Standard care | Hazardous waste (prudent) | Cost is self-limiting |
| Iron blue | Standard care | Drain-safe | Ferric compounds are benign |
Selenium Toner Advice
Selenium is the most environmentally problematic common toner. Best practices:
- Replenish, don't discard. Working selenium toner lasts indefinitely if topped up with concentrate as it weakens.
- Use at high dilution. 1:9 to 1:19 extends life while still providing protection and tonal shift.
- Never pour down drain. Ever. Selenium is a persistent heavy metal toxin.
- When eventually exhausted: Hazardous waste collection only.
A well-maintained selenium toner bath can last years of regular use.
Mordançage
Mordançage uses copper chloride bleach—a genuine environmental concern.
The problem: Copper is toxic to aquatic life at very low concentrations (EPA freshwater criterion: 2.3 μg/L). Working mordançage solution contains ~10g copper per litre.
The mitigation: The bleach is reusable virtually indefinitely.
Copper in mordançage cycles between oxidation states during bleaching but isn't consumed. When the bleach weakens (slower action), top up with hydrogen peroxide to regenerate the oxidised copper. The same batch can process hundreds of prints over years.
Per-print burden decreases with use:
- 100 prints from one batch = 50mg copper per print
- 500 prints = 10mg copper per print
- 1000 prints = 5mg copper per print
When eventually exhausted:
- Neutralise with sodium hydroxide (forms copper hydroxide precipitate)
- Let precipitate settle
- Decant liquid (much less hazardous)
- Collect precipitate for hazardous waste disposal
Key practice: Never discard mordançage bleach casually. Reuse it until it truly cannot be regenerated.
Chromoskedasic Sabattier
Chromoskedasic sabattier (“chromo”) produces striking metallic colours but uses ammonium thiocyanate—an aquatic toxin.
Critical distinction:
| Method | Chemistry per Session | Waste Generated |
|---|---|---|
| Tray immersion | 500ml–1L each solution | Significant hazardous sludge |
| Brush application | 40–60ml total (diluted) | Minimal |
Use brush application only. Tray methods generate unacceptable waste volumes.
Brush technique:
- Partially develop print, rinse
- In room light, apply diluted stabiliser (1:4) with brush to selected areas
- Apply diluted activator (1:4) with separate brush to other areas
- Colours develop where solutions meet on print surface
- Fix briefly, wash, dry
Most chemistry ends up on the print itself, not in waste containers.
Collect all waste, even small amounts from brush washing. Hazardous waste disposal required.
Disposal Reference
Drain-Safe (with dilution)
These can be poured down the drain with running water:
- Wash water (after initial rinse)
- Oxidised B&W developer (brown or black colour indicates exhaustion and oxidation)
- Neutralised stop bath (add sodium bicarbonate until fizzing stops)
- Sepia/sulfide toner (after use, well diluted)
- Cyanotype rinse water (iron compounds are benign)
- Steel wool treated fixer (after silver removal verified)
Hazardous Waste Required
These must go to proper hazardous waste collection:
- All fixer before silver recovery, or if recovery incomplete
- Colour developer (C-41, RA-4, E-6)
- Colour bleach (ferric EDTA)
- Colour blix / bleach-fix (contains silver)
- Selenium toner (when eventually exhausted)
- Mordançage bleach (when eventually exhausted; neutralise first)
- Chromoskedasic solutions (both stabiliser and activator)
- Dichromate solutions (gum bichromate—also carcinogenic; handle with extreme care)
Never Down the Drain
Under no circumstances:
- Untreated fixer (silver-laden)
- Colour blix (silver + persistent EDTA)
- Selenium toner in any condition
- Copper compounds (mordançage)
- Thiocyanate solutions (chromo)
- Dichromate (gum bichromate)
When in doubt, collect for hazardous waste. The cost of proper disposal is trivial compared to environmental damage from improper disposal.
Process Quick Reference
B&W Film Development
| Step | Practice |
|---|---|
| Developer | Choose for results; environmental difference is marginal |
| Stop | Water stop is simplest; acid stop works—neutralise before drain |
| Fix | Two-bath system: 30–60 sec first bath, 2–4 min second bath |
| Wash | Ilford method: 5-10-20 inversions, ~2 litres total |
| Fixer disposal | Collect → silver recovery → drain treated liquid |
B&W Printing (Fibre Paper)
| Step | Practice |
|---|---|
| Developer | Standard tray development |
| Stop | Water or neutralised acid |
| Fix | Two-bath: brief first, full second |
| Rinse | 2 tray changes before HCA |
| HCA | 10 minutes with agitation |
| Final wash | 3 complete tray fills, 2 min agitation each |
| Fixer disposal | Collect → silver recovery |
C-41 Film
| Step | Practice |
|---|---|
| Developer | 38°C ± 0.3°C; gloves |
| Blix or Bleach+Fix | Collect ALL |
| Wash | Standard |
| Disposal | All chemistry to hazardous waste; silver recovery from fix if separate |
Lith Printing
| Step | Practice |
|---|---|
| Developer | Extreme dilution (1+20+); uses less chemistry than standard |
| Stop/Fix/Wash | Standard B&W practices |
| Fixer disposal | Same as conventional—silver recovery applies |
Mordançage
| Step | Practice |
|---|---|
| Bleach | From stored stock; reuse indefinitely |
| After session | Return bleach to storage; top up H₂O₂ if needed |
| Disposal | Only when truly exhausted (years); neutralise first |
Checklists
Every Session
Start:
- Fixer tested recently—baths still good?
- Silver recovery system has capacity?
- Waste containers available and labelled?
- HCA mixed (if printing fibre)?
- PPE ready (gloves for colour)?
End:
- Fixer to collection container—NOT drain
- Developer disposed appropriately (drain if exhausted B&W; hazardous if colour)
- Stop bath neutralised if acidic
- Colour chemistry to hazardous waste container
- Equipment rinsed (first rinse to appropriate container)
- Work area clean
- Session logged
Monthly
- Test both fixer baths
- Check silver recovery progress
- Rotate fixer baths if first tests exhausted
- Verify hazardous waste container capacity
- Replenish selenium toner if in use
- Check mordançage bleach activity
Annually
- Arrange hazardous waste collection
- Dispose of accumulated silver sludge (refiner or hazardous waste)
- Review practices—any improvements to make?
- Check chemical expiry dates
- Deep clean equipment
Summary
Five practices that matter:
1. Recover silver from all fixer.
Steel wool method for home darkrooms—cheap, simple, 95–99% effective. This single action addresses ~80% of your environmental impact.
2. Use two-bath fixing.
Extends fixer life 4–10×. Ensures archival quality. Concentrates silver for easier recovery. Test don't guess.
3. Wash efficiently.
Ilford method for film: 5-10-20 inversions, ~2 litres per roll. HCA + sequential trays for fibre prints: ~10–15 litres per session. Understand the physics—diffusion, not flow.
4. Dispose properly.
Fixer never goes down the drain without treatment. Colour chemistry to hazardous waste. Selenium, copper, thiocyanate—collect and dispose responsibly.
5. Reuse what you can.
Mordançage bleach lasts years. Selenium toner replenishes indefinitely. Two-bath fixing dramatically extends fixer life. Don't discard prematurely.
The result is a darkroom practice that addresses its actual impacts—proportionate, practical, sustainable.
Not perfect. Not zero-impact. But honest about what matters and responsible about managing it.
Sustainable Darkroom series