I’m glad this resource is useful for folks.

Regarding my development methods with Diafine, at it’s simplest I develop for 5+5 and use continual roller agitation.

My more detailed response is to consider time, temperature and agitation.

Conventional wisdom regarding temperature is that Diafine is most sensitive to differences in temperature. Best results are near 68 degrees Farenheit, and increases or decreases will affect contrast. I’m happy with my results matching temperatures by feel, and don’t have any consistency issues, so I don’t normally bother with a thermometer.

I don’t presoak or prewash. I use development times of 5 minutes in Solution A and 5 minutes in Solution B. My rationale is based on the fact that Diafine develops “to completion”. By putting dry film into Solution A for the full five minutes, I can get as much developer soaked into the film as possible. It’s the Solution A that is soaked into the film that will be carried over into Solution B. Leaving the film in Solution B for five minutes will allow all of Solution A combined with Solution B to do their work until Solution A is exhausted. In fact, the Solution A may be exhausted well before five minutes elapses — but there is no harm leaving the film in Solution B as long as five minutes, and it will ensure exhaustion actually occurs.

When I began using Diafine, I followed my usual practice of agitation for 10 seconds, at sixty second intervals. However, a couple of years ago I had two things happen. First, I had a roll of film that showed the effects of “bromide drag” which is uneven development usually caused by insufficient agitation. Second, I was running low on mixed Solution A and Solution B. As a result, I have switched to a low-rent version of rotary processing. Using newish Paterson tanks in good condition, I burp the air out of the top lid and the tank becomes very water-tight. I then lay the tank down on its side and roll the tank gently back and forth from one hand to the other hand. This allows me to use slightly less volume of developer and constantly agitate the developer. I found an immediate benefit in evenness of development and full tonality. I worried that grain would become a problem, but haven’t seen any issues. Grain remains reasonable, and when developing 120 format film no problem at all.