Temperature Discipline

Most inconsistency is not chemistry. It is drift.

For the first year I blamed my results on film, on developer, on the scanner. The actual cause was that I never measured anything twice. The developer went in somewhere near twenty degrees and came out somewhere else, and every roll got a slightly different process.

What actually needs controlling

1. Developer temperature — the one that changes contrast. Half a degree is fine. Three degrees is a different negative.
2. Time — measured from when the developer goes in, not from when you finish pouring.
3. Agitation — same pattern, same interval, every time.
4. Rinse temperature — mainly to avoid shocking the emulsion between steps.

A routine that removed most of the variance

Nothing clever, just written down and repeated:

Step	Detail
Pre-soak	Two minutes, plain water at process temperature
Develop	Per the chart, agitate 10 seconds each minute
Stop	Water, three changes
Fix	Fresh fixer, timed — twice the clearing time
Wash	Fill-and-dump, five cycles with increasing rests
Wetting agent	Thirty seconds, no agitation

Agitation

Too little gives uneven development and streaks off the sprocket holes. Too much raises contrast and can produce surge marks. The middle ground — inversions for ten seconds at the start of each minute, then set the tank down — is boring and works.

Whatever you choose, write it in the log next to the roll number. Six months later that note is the only thing that explains why one roll looks different from the rest.

Keeping a log

One line per roll: film, rated speed, developer, dilution, temperature, time, agitation, date. It takes twenty seconds and it is the difference between a practice and a series of accidents.