Development

You have composed your image, metered the light, set your aperture and shutter speed, and pressed the shutter release. Inside your camera, light struck the emulsion and formed an invisible pattern of changed silver halide crystals — the latent image. Now comes the transformation: turning that invisible chemical whisper into a visible, permanent photograph. This is development, and it is where the magic of film photography becomes tangible.

Film development is a chemical amplification process. Each exposed silver halide crystal in the emulsion contains only a tiny cluster of metallic silver atoms — perhaps four to ten atoms, formed where photons struck the crystal during exposure. This speck is far too small to see, even under a microscope. The developer amplifies this signal by a factor of roughly one billion, reducing the entire exposed crystal to metallic silver while leaving unexposed crystals largely untouched. The result is a visible image made of pure silver particles suspended in gelatin.

The Chemistry of Development

Film development involves a precise sequence of chemical baths, each performing a specific function. Understanding what each step does — and why it matters — gives you control over the final image in ways that go far beyond simply following a recipe.

The developer is the heart of the process. A developing agent is a chemical reducing agent that donates electrons to silver ions in the silver halide crystals, converting them to metallic silver. The key to the process is selectivity: the latent image specks on exposed crystals act as catalysts, dramatically accelerating the reduction reaction at those sites. Unexposed crystals develop far more slowly, which is what creates the difference between image areas and clear areas on the negative.

Most practical developers contain two developing agents working together. Metol (also called Elon) works quickly and produces detail in shadow areas. Hydroquinone works more slowly but produces dense highlights. Together, they exhibit superadditivity — the combination is more effective than either agent alone. This synergistic pairing was discovered in the late 19th century and remains the basis for many developers used today, including the venerable Kodak D-76, introduced in 1927.

Beyond the developing agents, a developer solution contains several other essential components. An alkali (typically sodium carbonate or borax) maintains the pH at the alkaline level needed for the developing agents to function. A preservative (usually sodium sulfite) prevents the developer from oxidizing in the solution before it can do its work. A restrainer (typically potassium bromide) slows the development of unexposed crystals, improving the selectivity of the process and reducing fog — the unwanted overall density that would lower image contrast.

The stop bath immediately follows the developer. It is typically a dilute solution of acetic acid (essentially diluted vinegar) that abruptly halts development by lowering the pH from alkaline to acidic. Without a stop bath, development would continue unevenly as you drained the developer, leading to inconsistent results. Some photographers use a plain water rinse instead, which is gentler on the film but less decisive in stopping development.

The fixer (also called hypo, from its old chemical name sodium hyposulfite, now properly known as sodium thiosulfate) performs the crucial task of dissolving all remaining unexposed silver halides from the emulsion. Before fixing, the film is still light-sensitive — if you exposed it to light at this stage, the remaining silver halides would darken and obscure the image. The fixer converts these silver halides into soluble silver-thiosulfate complexes that wash away in water, leaving behind only the developed metallic silver image in a clear gelatin matrix. After fixing, the film is no longer sensitive to light.

The wash step removes residual fixer and dissolved silver compounds from the emulsion. Incomplete washing leaves thiosulfate ions in the gelatin, which over time react with the silver image to form silver sulfide — a yellowish-brown stain that degrades the image. Archival washing standards, as defined by Ilford's method, typically call for a sequence of fill-and-dump water changes rather than continuous running water, which is both more effective and more water-efficient.

Finally, a wetting agent (such as Kodak Photo-Flo or Ilfotol) is added to the final rinse. This reduces the surface tension of the water clinging to the film, allowing it to sheet off evenly rather than forming droplets that leave water spots as they dry. A single drop in the final rinse tank is usually sufficient.

The Development Process Step by Step

The practical workflow begins in total darkness. You must load the exposed film onto a reel and place it inside a light-tight developing tank before any light touches it. This is the only step that requires complete darkness — once the lid is securely on the tank, you can turn on the lights and work normally, pouring chemicals in and out through the tank's light-tight opening.

A pre-wet (or pre-soak) with plain water at the development temperature is optional but widely recommended. It brings the film and reel up to temperature, softens the gelatin so the developer can penetrate evenly, and washes out some of the anti-halation dye backing. You will notice the pre-wet water often turns purple or green — that is the dye doing its job.

Then the developer goes in. You pour it through the light-tight opening, start your timer, and begin your agitation pattern. Development times vary enormously — from around 5 minutes to over 20 minutes depending on the film, developer, dilution, and temperature. When time is up, you pour out the developer (or dump it, if it is a one-shot developer used at working strength).

Stop bath goes in for 30 seconds with continuous agitation. Then fixer, typically for 3 to 5 minutes. After fixing, you can open the tank and admire your negatives for the first time — but resist the urge until the wash is complete. A thorough wash of 5 to 10 minutes removes all fixer residue. A final rinse with wetting agent, and you hang the film to dry in a dust-free environment for an hour or two.

The Developing Tank and Reel

The two most common developing tank systems are the Paterson (plastic, adjustable for 35mm and 120 film) and stainless steel tanks with matching stainless reels (such as those made by Hewes or Kindermann). Each has its partisans.

Paterson reels use a ratchet mechanism: you feed the film leader into the outer edge of the reel and then twist the two halves back and forth, which walks the film into the spiral grooves automatically. This is generally easier for beginners but can jam if the reel or film is damp. Stainless steel reels require you to bow the film slightly and slide it into the center of the spiral, feeding it outward. This takes more practice but, once mastered, is faster and more reliable. Many darkroom veterans swear by stainless steel; many others have used Paterson reels happily for decades.

Loading film onto the reel is the single most anxiety-inducing part of the process for newcomers. It must be done in complete darkness — either in a dedicated darkroom or inside a light-tight changing bag. Practice with a sacrificed roll of expired film in daylight until the motions become automatic. You need to be able to do it entirely by feel.

Common Developers

The choice of developer is one of the most significant creative decisions in black-and-white photography. Different developers produce different grain structures, tonal ranges, and levels of sharpness. Here are the most widely used formulas:

Kodak D-76 / Ilford ID-11: These are essentially the same formula — a fine-grain metol-hydroquinone developer that has been the standard reference since 1927. Used at full strength, D-76 produces fine grain with smooth tonal gradation. Diluted 1:1, it gives slightly more apparent sharpness with a modest increase in grain. D-76 is the developer against which all others are measured, and it remains an excellent choice for nearly any black-and-white film.

Kodak HC-110: A highly concentrated liquid developer that mixes directly from the syrup. Its main advantage is convenience — the concentrate has an extremely long shelf life (years, in practice), and you mix only what you need for each session. Dilution B (1:31 from concentrate) is the most common starting point. HC-110 produces slightly more grain than D-76 but offers excellent sharpness and consistent results.

Agfa Rodinal (now Adox Adonal): Arguably the oldest photographic developer still in production, dating to 1891. Rodinal is a single-agent developer (p-aminophenol) used at high dilutions — typically 1:25 for normal use or 1:50 for stand development. It produces pronounced, sharp grain with outstanding edge sharpness (acutance). Many photographers love the distinctive "Rodinal look," particularly with medium- and large-format films where the grain structure is less of a concern.

Kodak Xtol: A more modern developer introduced in 1996, using ascorbic acid (vitamin C) as part of its developing agents. Xtol produces exceptionally fine grain — finer than D-76 in many tests — while maintaining good film speed. It is an environmentally friendlier option, as it contains no hydroquinone. Xtol works well with virtually all black-and-white films and is especially popular with photographers shooting Kodak Tri-X and T-Max films.

Temperature Control

Temperature is critical to consistent results. The standard temperature for most black-and-white development is 20°C (68°F). Development is a chemical reaction, and like all chemical reactions, its rate increases with temperature. The rule of thumb is that a 1°C increase in temperature speeds development by roughly 10%. This means that even small temperature variations — particularly plus or minus 0.5°C — can measurably affect density and contrast.

To maintain consistent temperature, many photographers use a water bath: placing the developer bottle and the loaded tank in a basin of water at the target temperature before beginning. An accurate thermometer is essential — not the kind you use for cooking, but a purpose-made photographic thermometer or a high-quality digital thermometer with 0.1°C resolution.

If your tap water or ambient temperature makes 20°C impractical, development times can be adjusted for other temperatures. Published time-temperature charts (or the Ilford method: reduce time by 10% per degree above 20°C, increase by 10% per degree below) allow you to compensate. However, temperatures above about 24°C risk softening the gelatin emulsion, and temperatures below about 18°C can produce uneven development. Staying close to 20°C avoids these problems.

Agitation

Agitation — the physical motion of the developer solution across the film surface — is the other critical process variable alongside temperature. As developer acts on the emulsion, it becomes locally exhausted (depleted of developing agents) and the reaction byproducts (primarily bromide ions) accumulate near the film surface. Without agitation, these byproducts suppress further development in highlight areas where the reaction is most active, leading to uneven density and reduced contrast.

The standard agitation pattern for most developers is: continuous agitation for the first 30 seconds (to ensure even wetting and initial development), then 3 to 4 inversions every 30 seconds (or every minute, depending on the developer). An inversion means turning the tank upside down and back over the course of about one second. After each set of inversions, tap the tank gently on a hard surface to dislodge any air bubbles that may have formed on the film surface.

More frequent agitation produces higher contrast, because fresh developer is constantly supplied to the highlights. Less frequent agitation (or stand development, where the tank is simply left undisturbed for long periods) reduces contrast by allowing the bromide buildup to act as a natural restrainer in highlight areas. This adjacency effect — where the bromide from heavily exposed areas drifts into adjacent less-exposed areas — also enhances edge sharpness, producing a distinctive look prized by some photographers.

Development Time and the Massive Dev Chart

Development time is determined by the specific combination of film stock, developer formula, dilution, and temperature. There is no single universal time. A roll of Ilford HP5 Plus developed in D-76 at full strength at 20°C requires approximately 7.5 minutes. The same film in Rodinal at 1:50 requires about 13 minutes. Kodak Tri-X in HC-110 Dilution B requires about 6 minutes.

The Massive Dev Chart (massivedevchart.com) is the single most valuable resource for development times. This community-maintained database contains thousands of film-developer-dilution combinations, crowdsourced from photographers worldwide. Manufacturer data sheets (from Kodak, Ilford, Fuji, and others) provide official starting times, but the Massive Dev Chart offers a broader range of combinations and user-reported variations that often prove more practical than the manufacturer's conservative recommendations.

When no published time exists for your specific combination, you can estimate by finding the time for a similar film and adjusting. Films of similar speed and type (traditional-grain vs tabular-grain) tend to behave similarly. Always bracket your first attempt: develop one roll at the estimated time, evaluate the results, and adjust by 10-15% for subsequent rolls if needed.

Push and Pull Processing

Push processing means intentionally underdeveloping the film — wait, that is backwards. Let us be precise. Pushing means rating the film at a higher ISO than its box speed (underexposing the film) and then overdeveloping to compensate. Pulling is the opposite: rating the film at a lower ISO (overexposing) and underdeveloping.

Pushing is common in low-light situations. A photographer shooting Tri-X (ISO 400) might rate it at ISO 1600 — a two-stop push. This underexposes the film by two stops. To compensate, the development time is extended, which increases the density of the highlight and midtone areas on the negative. However — and this is important — pushing does not truly increase the film's sensitivity. The shadow areas, which received very little light during the underexposure, cannot be developed into something that was never there. The result is increased contrast: brighter highlights and midtones, but shadows that remain thin and lack detail. Many photographers embrace this high-contrast look, which is a staple of photojournalism and street photography.

Pulling is less common but useful when you want to reduce contrast — for example, when shooting on a very bright, contrasty day. Rating Tri-X at ISO 200 and pulling the development gives a flatter, lower-contrast negative with more shadow detail and less dense highlights. This is essentially the development side of the Zone System's N-minus concept, which we will explore in Lesson 18.

The Darkroom

For film development, you do not need a full darkroom with an enlarger and running water. You need only a space that can be made completely dark for the few minutes it takes to load film onto the reel. A bathroom with towels stuffed under the door, a closet, or a changing bag will all work. Once the film is in the sealed tank, you can work in any room.

A changing bag is a light-tight fabric bag with elasticized arm holes. You place the film, reel, tank, and scissors inside, zip it closed, and work by feel through the arm holes. It is portable, affordable, and eliminates the need to light-proof an entire room. For 120 film, a large changing bag is essential — the paper backing and spool take up more space than 35mm.

If you do set up a dedicated darkroom for both development and printing, the room needs to be ventilated (darkroom chemicals produce fumes, particularly the stop bath), have running water for washing, and have both a completely dark mode (for film loading and paper handling) and a safelight mode (for printing, which we cover in the next lesson).

C-41: The Color Negative Process

Everything discussed so far applies primarily to black-and-white negative film. Color negative film uses the C-41 process, which is standardized across all color negative films — from Kodak Portra to Fuji Superia to Cinestill 800T. This standardization is one of the great conveniences of color negative photography: unlike black-and-white development, where every film-developer combination requires its own time, C-41 uses the same time and temperature for every film.

The C-41 process requires precise temperature control at 38°C (100.4°F), which is substantially warmer than black-and-white processing. The development step is 3 minutes and 15 seconds. Temperature tolerance is tight: plus or minus 0.3°C. This precision requirement initially seems daunting, but a sous-vide cooker or a simple water bath with a thermometer makes it quite manageable.

The C-41 chemistry sequence is: developer, bleach, fixer (or a combined blix step), wash, and stabilizer. The developer produces the silver image and, simultaneously, the color dyes in each of the three emulsion layers. The bleach then converts the metallic silver back to silver halide (we want only the dye image in a color negative, not the silver). The fixer dissolves the silver halide, leaving just the dye images. The stabilizer hardens the emulsion and provides long-term dye stability.

Home C-41 processing kits (such as the Cinestill Cs41 kit, Tetenal Colortec, or the FPP C-41 kit) make color development accessible to anyone willing to manage the temperature. In some ways, C-41 is actually easier than black-and-white at home — the times and temperatures are fixed, so there are no development charts to consult. The only variable is temperature precision.

After Development: Handling Your Negatives

Once your film is developed, washed, and dried, you have a strip of negatives — the permanent record of your photographs. Handle them with care. Hold film by the edges only, never touching the emulsion surface. Fingerprints contain oils and salts that can etch the gelatin permanently. Cut the film into manageable strips (six frames for 35mm, or three to four frames for 120/6x6) and store them in archival negative sleeves made of acid-free glassine or polypropylene. Never use PVC sleeves, which release chemicals that degrade the image over time.

Your negatives, properly processed and stored, will last for generations. Silver gelatin negatives from the 1800s survive in archives today, their images still sharp and clear. The permanence of the silver image — when properly fixed and washed — is one of film photography's enduring advantages.

With your negatives in hand, you are ready for the next step: turning those small, reversed images into full-sized prints. In the next lesson, we will enter the darkroom and explore the art and craft of photographic printing.