Time/temperature variation in Print dseveloping

[Jim Benson]

I’m looking for a time temperature variation formula for RC and FB prints.

I’m unable to precisely control the developer temperature in the darkroom I currently use, though I do what I can to have some influence. Currently I place bell jars full of ice in the developer tray while I’m cycling through the rest of the chemicals.. I am usually able to keep the temperature within a 5 degree Fahrenheit range

I’m using sprint chemistry and printing Ilford multigrade 16 x 20. I’m currently printing RC but will be moving to FB.

The Sprint technician suggested that I just develop at room temperature, and while there’s a certain appeal to that, even then the temperature will shift from day to day. And although I’m told that there is a new heating/cooling system going in, the room temp goes into the 8os in the Summer, and if the new system doesn’t go in, there’s no way around the ice treatment.

After asking various other sources how to vary print development times with temperature without getting any answers at all, I went to the Ilford web site. (Well, duh!!!)


They gave the following variations for RC paper, but these are for using a processing machine They don’t give any numbers for FB paper.

20/68 46 seconds
25/77 32 seconds
30/86 22 seconds
35/95 15 seconds
40/104 12 seconds

If one were to do simple arithmetical projections for one minute at 68 F for Tray development of RC paper and three minutes for FB paper the numbers would be
RC (with numbers rounded)
20/68 60 seconds
25/77 42 seconds
30/86 29 seconds
35/95 20seconds
40/104 16 seconds


For FB (with numbers rounded)
20/68 180 seconds
25/77 2 minutes and 5 seconds
30/86 one minute and 26 seconds
35/95 59 seconds
40/104 47 seconds

I’m assuming that this works as far as it goes, but I need to come up with viable numbers for temperatures between 68 F and 77F. (I don’t expect to have to worry about higher temps than that)

Given that the time difference lessen as the temperature goes up, simply subtracting 2 seconds for every degree hike (RC) or 6 seconds for every degree hike (FB)will not be the best practice. It’s obvious that one should subtract a bit more at the beginning to that scale (68-69) and less at the other end (76-77). How can I arrive at those numbers? And is my initial assumption, basic arithmetical projection, correct?

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And, for a bonus question----


I have been wondering about the mechanics of drain times between trays. I had been taught that you should drain your print back into the tray it was just immersed in, until the steady stream from the bottom corner turns into a drip. The idea being to, as much as possible, keep the chemicals from the trays further down the line. While this may have taken 5 seconds (The figure I have in my notes) for 8 x 10s, in 16 x 20s it is more like 30 seconds.

I had been thinking that once the print was out of the tray and held vertically, most of the chemical is off the print, and little action is going on after that point. I do not count that towards the times I have for various chemicals. Thoughts and advice?

 

[MattKing]

Ralph Lambrecht and Chris Woodhouse are your friends - read here from their book "Way Beyond Monochrome" about Factorial development ("Development Factor").

https://books.google.ca/books?id=tY...#v=onepage&q=developer emergence time&f=false

The emergence time determines your total development time. And the emergence time will be a function of chemical capacity and the ambient temperature.

And with respect to draining the print, if it is essentially fully developed when you start draining it, then very little additional development will take place. But if the development is incomplete, there will be substantial additional development while you drain it.

 

[snapguy]

art

Making a great photo print is as much an art as a science. Numbers alone will not do it. You need to plug into your instinct, as well.

 

[Bill Burk]

Hi Jim Benson,

Welcome to APUG. I don't have a direct connection to this seller, but I use this software/hardware system to manage my film and development times with varying temperatures.

http://curtpalm.com/Software.html

Even the demo version allows you to see suggested slope/intercept values that will give you insight into time versus temperature adjustments.

 

[eddie]

Zone VI made a compensating development timer, which adjusted the timer based on the temperature of your developer. If your first print was at 68 degrees, but the temp rose (or fell) it would automatically decrease (or increase) the time. They're hard to come by, but Curt Palm makes a similar device, which might be worth looking into: http://curtpalm.com/Software.html

 

[eddie]

Bill beat me to it, and has first hand knowledge.

 

[gone]

A 5 degree spread in temps is more than I would be comfortable with, even though paper developing is not as temperature critical as film developing. Unlike film, you're going to be developing your paper to completion, so adjust the times for your temp in your darkroom. Translation: make some tests. Some darkroom paper developers are not as sensitive to having to keep the temps spot on, but if it's too warm you're going to get things messed up..

 

[ic-racer]

What kind of development problems have you been having. Can you post some examples? Without seeing them, I suspect it is under-development if you are 'snatching' the prints at some 'exact time'.

Development can be extended up to 6 minutes without
any noticeable change in contrast or fog. --Ilford MG FB package insert.

 

[philosli]

I believe in normal case you develop your paper to completion, as ic-racer said. The temperature and time is not that important, as long as the temperature is not too low (low development activity) or too high (e.g., one of the two active ingredients in Dektol will become dominant, according to Adams's "The Print"). You use exposure time to control the lightness of the print, and select the paper grade for contrast control.

As far as I understand (I could be wrong), the factorial approach, also discussed in "The Print", is used to control the contrast. This is because the low value (shadow) develop first. You can reduce the development of the highlights by shortening the development time to achieve higher contrast (for example, less than 1/2 grade difference).

 

[RalphLambrecht]

Well,yes,that's what fractional development is for.it compensates for a few variables such as temperature,aging developer or paper; it works best for FB but still worth a try for RC

 

[bernard_L]

Don't waste too much sleep over time-temperature for papers. As already stated, paper is developed to completion. Make a simple experiment, at a "normal" temperature (20°C, give or take). Expose 5 identical small prints with a representative range of tones. Mark them on the back before they go into the developer. Develop for 1', 1'30", 2', 3', 5'. What do you see with your eyes? On which side is it better to err?

As far as I'm concerned, the real problem is printing in winter in a poorly heated room; the ambient temperature can be as low as 13°C~55°F. I'm considering to buy heating mats (sold for reptiles), so that I can heat the developer (and fixer?) tray without the need to heat the whole room to 20°C.

 

[David Allen]

Temperature variations between different printing sessions will not cause you any problems.

For each printing session you simply need to determine the minimum development time required to achieve maximum black. To do this, do one test strip to identify roughly what is the minimum exposure time to achieve black will be. Then do a series of 5 small test prints where you expose each of them for double the time you identified as being the rough minimum exposure (i.e if your very first test indicated 10 seconds then expose the 5 test prints for 20 seconds). Number the test prints on the back from 1 - 5 and then develop them for 1 minute, 2 minutes, etc. Give the prints your normal fixing and give them a quick wash and then dry them (this is very important for FB paper and the easiest way of doing this quickly is to get a cheap second-hand microwave oven and use this to dry them).

Line the 5 prints side by side with the one with 1 minute development to the far left and the one with 5 minutes development to the far right. Now comes the key part of the test, look at each test print and identify which print has a maximum black. Usually, you will find that (with FB) the one with 1 minute development will look OK until you compare it to the one with 2 minutes development which will look darker, etc. Then repeat until you find the print that is darker than the one to its left but the one to its right is not any darker. The print that does this is your absolute minimum development time to achieve a true maximum black. You can always develop for longer than the minimum for the purpose of changing tonality, etc but never less.

In general, with the discontinued Polywarmtone, the discontinued Adox FPVC, the discontinued Kentmere FPVC and the current Foma Variant III and Adox MCC 110, I have found that, irrespective of a ± 5˚ degree variation from 20˚C, all of them require at least 3 minutes when developed in Tetenal Dokumol 1 + 6 to fully achieve a real black.

As to the question about how long to drain a print the KEY thing is to always do the same time irrespective of the size of paper (this includes tests). Complete and repeatable consistency is your target.

For example, I always remove the print from the developer at 3 minutes & 10 seconds and drain until 3 minutes & 30 seconds and then place in to the (in my case water) stop bath. It then stays in the stop bath until 1 minute & 10 seconds and then I drain until 1 minute & 30 seconds. It then goes in to the first fix bath (in my case fresh Adox Rapid Fixer at 1 + 4) and is removed at 2 minutes & 10 seconds and drained until 2 minutes & 30 seconds whereby it then goes in to the second fix bath. Then at 2 minutes & 10 seconds it is taken out to drain and placed in the plain water holding tray at 2 minutes & 30 seconds.

Best of luck with your printing.

David.
www.dsallen.de

 

[Jim Benson]

Time/temperature update

Thank you all for your replies.

I downloaded the recommended software, but couldn’t make get anything out of it; probably more a matter of my limitations with computers than any limitations with the software.

I have a copy of Way Beyond Monochrome on order.

More importantly, in my most recent darkroom sojourn, I managed to be able to return the developer to within .5 degree F of 68, although I had to let all the other chemicals lurk at room temperature. It’s not the ideal, but I didn’t see any problems. Maybe I’ll have a JOBO at some point, and will be able to put all of my attention elsewhere.

 

[Jim Benson]

Oops. Replied to wrong thread!