Film & darkroom
Film development temperature: control the actual bath
A water-bath plan and a record of what the thermometer measured.
Room temperature, water-bath temperature and developer temperature are separate observations. The recipe refers to the processing solution. A well-organised session checks the actual bath, rather than assuming that the room or heater display supplies that value.
Time belongs to a temperature
ILFORD’s DD-X technical sheet pairs development times with specified temperatures and film exposure indices. One example for DELTA 100 PROFESSIONAL at EI 100, dilution 1+4, is 10 minutes 30 seconds at 20°C. Use the matching row and processing method; do not transfer the example to another film.
Evidence: Technical data sheet
A rehearsal before the roll
Our temperature rehearsal uses water in the intended containers. Place them as they will stand during processing, then record the starting reading and another reading after the expected session duration. Check that the measuring device can read the range clearly. This identifies drift without risking exposed film.
Write observations, not assumptions
Record solution temperature just before use, together with the time and measuring location. If the working bath is outside the documented condition, resolve it before beginning rather than inventing an adjustment mid-roll. Keep the source’s approved time-temperature guidance beside your notes when an alternative temperature is supported.
Sources & further reading
Sources for the specific facts and product descriptions above. Our worked examples, interpretations and practical suggestions are original editorial guidance.
- ILFORD PHOTO — ILFOTEC DD-X technical dataTechnical data sheet