Optimum Development Temperature?

G

giganova

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I'm starting to develop my B&W film myself. Questions:

How critical is the "optimum" 20c temperature that is given in most tech sheets for film development? The air conditioning in my house is set to a constant 27c = 80F and I'd like to develop at that temp because all my chemicals are thermalized at that temp.

Is it best to chill down the chemicals to 20c with ice or can I develop at 27c and use the appropriate correction for the development time (e.g. 5min @ 20c instead of 9min @20c)?

Would the higher temp affect the grain and contrast curve?
 
Welcome to Rangefinder forum.

Higher temperature equals less time developing and greater chance for error. 30 second error with 5 minute development can cause more to the negatives than 30 seconds with a 10 minute developing time.

Maybe, with your room temperature, to put the tank in a bowl of water chilled to a lower temperature.

Sometimes I will put an ice cube in the bowl to help maintain the lower temperature.
 
As Bill just said, a few seconds difference in a ten minute time is very different from a few seconds at four minutes. I tried higher temp developing a couple of times and found that the resulting negatives looked splotchy in a wavy sort of way. Almost like the film didn't absorb the developer evenly. Cold fresh water was a low cost ubiquitous resource so I never went down that road again.

You might look into pre-soaking your film at the same temperature you're developing at. Not too long, perhaps three minutes, just enough to get the emulsion ready to accept the developer chemicals evenly. I seem to remember something about that somewhere deep in the old silly knowledge bank but I'm not 100% sure.

You might want to run a couple of test lengths of film through the process. Fill the frame with a neutral gray card (or wall) and then look at the negatives through a very high powered loop. Cut the roll in thirds and develop the first at a few degrees higher than your target temperature, the next at your target, and the third at say between the preferred temp and your target. Look for patterns in what should be an otherwise patternless negatives.

Good luck, let us know how you make out.

B2
 
In your situation I'd cool to 24C/75F, my standard dev temperature anyway. The longer times are easier to control, but "drift" with 3 degree difference to ambient is likely to be trivial. I normally use a water bath (a tray of water at the right temperature).

Are you using steel tanks or plastic? The latter take longer to warm up/cool down.

Cheers,

R.
 
Roger Hicks said:
Are you using steel tanks or plastic? The latter take longer to warm up/cool down.
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Jobo plastic tanks and rolls, but I'm thinking about changing to steel anyway.

I guess I could just fill up the sink with 24C/75F water, let the developer sit there for a while until it dropped to that temperature, and soak the film in the Jobo tank filled with water at the same temp for a few minutes before I get started developing.
 
When I process at home, I*normally stabilize all chemistry to be at room temperature. BUT ... if the development time goes under 4 minutes, I either hold off and do the processing at another (cooler) time or I cool the chemistry down.

I find a development time in the 70 to 75°F range for 5-7 minutes, placed there by the combination of temperature and developer concentration, generally nets my best results.

G
 
I'm mostly concerned about consistency here:

While I realize that a temp in the 20c/70F range might be optimal, cooling down the chemicals, tank, etc, might introduce more errors than if I'd always develop at the very constant, higher temp in my house.
 
The above advice is all good. Another route might be to use a more dilute developer which will give you a longer developing time. For instance, D-23 works at about seven and a half minutes at 20 degrees C if the developer is used straight. If diluted 1:3, the times rise to somewhere between 20 and 24 minutes. Which developer are you using?
 
giganova said:
Are you suggesting that I should get up earlier in the morning to develop my film?? ;)
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Or stay up way later.

Not sure where you are located. But at night around here in Iowa the temp drops. If you put your chemicals, film and such where it can be effected by the night cold it might lower the temp enough to be in the recommended range.

For example if the temp by you drops to 75F over night you might wake up at 4:30 AM to soup (develop) your film then go back to bed when you are done.

Just trying to think outside the box a bit.

B2 (;->
 
giganova said:
Jobo plastic tanks and rolls, but I'm thinking about changing to steel anyway.

I guess I could just fill up the sink with 24C/75F water, let the developer sit there for a while until it dropped to that temperature, and soak the film in the Jobo tank filled with water at the same temp for a few minutes before I get started developing.
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That's what I'd do. With a big enough thermal mass in the water bath (a washing up bowl is ideal) you can get very high consistency, especially if the difference in temperature between the water bath and the room is only 3 degrees.

Cheers,

R.
 
I've heard two stories about John Sexton on development temperature: he uses 75-F because the water where he lives won't go down to 68-F, the second version is that he honestly feels 75-F gives him a better product with Tmax400 (and maybe other films).
 
I develop at either 68 or 75. I have never seen a quality difference between them, as long as the 75 degree developing time is not so short that it allows uneven developing to occur. You have to use the correct time for the temp you chose, of course.

I use 68 in winter, and 75 in summer. The tap water where I live never gets as cool as 68 degrees in summer.
 
Feedback:

Developed my first two films at 75F, FP-4 and HP-5 pushed to 800ASA in the same Jobo tank, Ilford DD-X for 8 min, agitated for 10 sec every minute.

Results are perfect! :)
 
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