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Why a darkroom timer matters
Film development is a sequence of timed baths, and the sequence does not forgive guesswork. Developer first, for a precise number of minutes. Then stop bath, which halts development. Then fixer, which makes the image permanent. Then a wash, which removes the chemistry. Get any stage badly wrong and the negative suffers: too long in developer means harsh contrast and heavy grain, too short in fixer means an image that fades over months. A timer that calls out each stage is the simplest tool that stands between a good negative and a ruined one.
This timer runs entirely in your browser and uses sound, because in a darkroom you cannot watch a screen. Enter your four stage times in minutes, press start, and the timer counts down each stage, beeping as stages change and giving a warning beep ten seconds before each change. It also shows the current stage and the time left in large text, for the moments when you can glance at a dim screen. The timer only sounds while this page stays open, so keep the tab open and your sound on, and do not let the device sleep mid-development.
The four stages explained
Developer is the stage that matters most. It converts the invisible latent image into visible silver, and its time sets the contrast and density of the negative. Agitate gently on a regular schedule, typically ten seconds every minute, by inverting the tank or twisting the agitation stick. Consistent agitation matters as much as consistent time: uneven agitation gives uneven development, visible as streaks or blotches.
Stop bath follows immediately. It is usually a weak acid that neutralises the alkaline developer and stops development dead. One minute is typical, with continuous gentle agitation. Some photographers use a plain water rinse instead of stop bath, which works but stops development more slowly, so keep it brief and consistent if you choose that route.
Fixer makes the image permanent by dissolving the unexposed silver that the developer left behind. Five minutes is common for fresh fixer, but fixer weakens with use, so extend the time as it ages and test it regularly: a scrap of unexposed film should clear completely within a couple of minutes, or the fixer is exhausted. After fixing, the film is safe in normal light.
Wash removes the fixer and other chemicals from the film. Ten minutes in running water is a common standard, and thorough washing is what makes negatives last for decades instead of yellowing within years. A wash aid can shorten the wash, but plain running water, changed regularly, does the job reliably. Hang the film to dry in a dust-free place after washing, and handle it only by the edges.
A worked example
A typical black and white sequence might be eight minutes in developer, one minute in stop, five minutes in fixer, and ten minutes in wash, twenty-four minutes in total. Enter those four numbers, press start, and the timer walks you through: it shows Developer with eight minutes counting down, beeps a warning at ten seconds left, beeps three times at the change, and moves to Stop bath. You pour out one solution and pour in the next during the changeover, which is why the warning beep matters: it tells you to have the next bottle ready.
Colour film follows the same pattern with different times and usually tighter temperature control: enter the colour process times from your kit’s instructions instead of the black and white defaults. Push processing, where you extend development to compensate for underexposure, is also simple: enter the extended developer time and the rest stays the same.
Darkroom habits that save film
Prepare everything before the lights go out. Line up your four solutions in order, check their temperatures, and put the timer where you can hear it. Label bottles clearly, because developer and fixer look identical in the dark and swapping them ruins film. Keep a towel and a spare graduate within reach, and know where everything is by touch before you start.
Work calmly at each changeover. Pour out completely, pour in promptly, and start agitation at once. Rushing causes spills, and spills in the dark cause confusion about which solution is in the tank. If you lose track, stop and think rather than guessing: a minute of thought costs less than a roll of film. After the wash, inspect the negatives while they are still wet and note any problems for next time.
Frequently asked questions
Will the timer work if I switch apps? Browsers may throttle background tabs, so keep this tab in the foreground and the device awake. The timer only sounds while the page stays open.
What if my process has different stages? Combine or split stages to fit the four slots, or set an unused stage to zero and the timer skips it. The total time shown updates to match.
Do I need sound? Sound is strongly recommended, because darkroom work is hands-on and eyes-busy. If your device is silent, watch the large countdown display, but sound is the safer option.
Use the timer above with your real stage times, keep the page open and the sound on, and let it call the changes while you concentrate on agitation and pouring. Good negatives come from consistent timing, and consistent timing is exactly what a timer gives you.
Related calculators
- Spanish version
- Film Development Time Temperature Calculator – Corrected Times When Developer Runs Hot or Cold
- Reciprocity Failure Calculator – Corrected Long Exposures for Film Photography