ποΈ Film Developing Timer
Darkroom countdown with agitation beeps, B&W film presets, and step tracking.
Ready. Pour in the developer and press Start.
Keep the phone out of the darkroom while loading film; bring it in only after the tank is closed. Times are starting points, always verify against the manufacturer chart.
How to Use This Timer
Developing black and white film is a timed chemical process where consistency beats perfection: the same time, temperature, and agitation every roll gives you predictable negatives. This timer handles the timing half. Pick your film and developer preset (or enter a custom time), set your agitation rhythm, and press Start the moment the developer hits the tank. It beeps at every agitation interval and tracks your progress through the development.
Choose a Film + Developer Preset matching your film, developer, dilution, and temperature. All presets assume 20 C (68 F) and box speed unless noted. Pick Custom time for push/pull or other developers.
Set the agitation rhythm. The default (every 30 seconds) suits most developers; 60-second intervals give slightly lower contrast and finer grain with some films.
Press Start the instant you finish pouring the developer. Agitate continuously for the first 30 seconds, then follow the beeps: each beep means 10 seconds of gentle inversions (5 seconds on the 15-second rhythm).
At zero the timer sounds a long tone: pour out the developer immediately and move to stop bath. The step tracker below the clock logs each completed agitation so you can review your rhythm afterward.
How Development Timing Works
Development is the growth of metallic silver in exposed film grains, and it never fully stops until the developer is poured out. Time is the main control: longer development builds more density and contrast, shorter development holds highlights back. That is why pouring out promptly at zero matters more than starting within a second or two; the last minute of development affects the highlights most.
Agitation exists to refresh exhausted developer at the film surface. Without it, bromide byproducts build up along edges and you get uneven, streaky negatives. The beeps enforce the rhythm: continuous for the first 30 seconds to establish even wetting, then brief periodic inversions. Gentle is key; violent shaking causes surge marks around the sprocket holes. Four slow inversions in 10 seconds is the classic motion.
Worked Example: HP5+ in D-76 1:1
You shot a roll of Ilford HP5 Plus at ISO 400 and mixed D-76 1:1 at 20 C. Select the HP5+ D-76 1:1 preset: 13:00 with 30-second agitation. At 20 C water bath, pour the developer and start the timer. Agitate continuously until 12:30, then rest. At each beep (12:00, 11:30, 11:00, and so on) do four gentle inversions over 10 seconds.
Say your darkroom is warm and the chemistry sits at 22 C. Development runs faster: multiply the time by about 0.8, giving roughly 10:24. Select Custom time, enter 10 minutes 24 seconds, and develop normally. Better yet, float the graduate in a 20 C water bath for five minutes first; temperature control beats time math for consistency.
Practical Tips
Standardize everything except the variable you are testing. Same thermometer placement, same inversion count, same pour speed. When a roll comes out thin or dense, you want exactly one suspect, not four. Keep a notebook: film, EI, developer, dilution, temp, time, agitation, and a one-line verdict on the negatives.
Respect the fixer and wash even though the timer only covers development. Under-fixed film looks fine today and turns brown in a year; fix for the full recommended time and test clearing with a film leader snippet. Wash for at least 5 minutes in running water (Ilford's fill-and-dump sequence works too), finish with wetting agent to prevent drying spots, and hang the film where dust cannot reach it.
Frequently Asked Questions
How long should I develop Ilford HP5 Plus?
At box speed (ISO 400) in Kodak D-76 1:1 at 20 C, HP5 Plus needs about 13 minutes. In Ilfosol 3 at 1:9 it needs about 6.5 minutes, and in HC-110 dilution B about 7.5 minutes. Times shift with temperature, dilution, and push processing, so always check the manufacturer chart for your exact combination.
What is the standard developing time for Kodak Tri-X 400?
Tri-X 400 at box speed in D-76 1:1 at 20 C develops for about 9.75 minutes (many round to 10). In HC-110 dilution B it needs about 7.5 minutes, and in XTOL 1:1 about 9 minutes. Pushing to ISO 800 adds roughly 30 to 40 percent to the time.
How often should I agitate during development?
The classic method: continuous gentle agitation for the first 30 seconds, then 5 to 10 seconds of agitation every 30 seconds (or 10 seconds every minute) for the rest of the time. Consistent, gentle inversions matter more than the exact scheme; pick one method and use it every time for repeatable negatives.
Why does developing temperature matter so much?
Developer activity roughly doubles every 10 C, so a few degrees change the effective development significantly. The standard is 20 C (68 F). If your chemistry is at 24 C, cut the time by about 20 percent; at 18 C, extend it by a similar amount. A thermometer and a water bath are the cheapest consistency upgrades in the darkroom.
What are the steps after the developer?
The standard sequence is: developer (the timed step), stop bath for 30 to 60 seconds (or a plain water rinse), fixer for the film manufacturer's recommended time (typically 3 to 5 minutes for rapid fixer), a wash of 5 to 10 minutes in running water, a wetting agent dip for 30 seconds, then hang to dry. This timer tracks the developer stage; keep the later steps consistent by habit.
Can I use my phone as a darkroom timer?
Yes, and this timer is built for exactly that: big countdown display, audible beeps at each agitation interval, and preset times so you are not squinting at charts with wet gloves. Keep the phone out of the darkroom during film loading (any screen light fogs film), and bring it in only once the tank is closed.