Unfortunately, I don’t have any personal experience with the Scala developer kit.
However, when determining unknown initial development times using the ‘conventional’ method with its five to six baths (Dokumol as the developer; my main film is Fomapan R100), I tried to start by using known values for that film in other developers as a guide and work from there to deduce suitable times.
So
,
a practical example
: for two old (expired over 14 years ago) Agfapan APX100 rolls from my freezer, I compared old time specifications for the APX100 from the Tetenal kit’s instructions with the times listed there for Plus-X-Plan.
Where necessary, I also consulted the table for the Foma developer kit.
Then, in the next step, I took the Plus-X-Pan time for ‘my’ current primary developer from a table and used that to work out a time for the APX 100.
A rough rule of thumb: the Tetenal primary developer was about twice as fast with Plus-X-Pan as my current developer. So I roughly doubled the Tetenal time for the Agfapan as well.
Bullseye :thumbs-up: . The two APX 100s that expired in 2009 turned out perfectly.
(Note: With today’s APX 100, reversal processing is no longer said to produce usable results.)
Of course, you have to take the film sensitivities into account: The old APX 100 should receive ISO 200/24 DIN exposure during development using the Tetenal kit.
Admittedly, the whole thing is a bit of a shot in the dark – but I didn’t know any better.
Second example, this time a bit of a long shot due to the limited data available
: I wanted to find out the initial reversal development time for Rollei infrared film ISO400/27DIN. As is well known, this is a negative film.
Plus-X-Pan served as the ‘reference film’:
In ‘my’ developer, Plus-X-Pan would need to be left in the bath for 7 minutes for reversal development.
In D-76, it would need about 6 minutes for negative development.
In D-76, the Rollei infrared film would need 10 minutes 50 seconds.
So I concluded that the Rollei infrared film would need around 12 minutes 40 seconds in ‘my’ initial developer.
As a guideline, 12 minutes actually proved to be accurate.
That said, with infrared film, testing is unavoidable: with a 720nm filter, this results in an extension factor of around 40 – but for important subjects, I always do a test series.
I had mistakenly overexposed the first test films by one or two stops. In that case, the appropriate initial development time was closer to 9 to 9½ minutes.
To return to the candidate
Fomapan 100R in the Adox Scala set
using this method:
The only process for which I can find figures for both films is
the one by Klaus Wehner
:
this
was
discussed here in the forum
years ago. Perhaps that will help you.
Mind you: the temperature there
is
22 degrees!
According to Wehner, Adox Scala 160 requires 19 minutes for the nominal speed, 22 minutes for ISO 200/24 DIN.
Fomapan R100 at ISO 200/24 DIN requires 11 minutes 30 seconds. So just under half the time at the same speed.
In the Adox Scala process, I find 8 minutes for Adox Scala 160 at 24 (!) degrees.
So you
could
try it with the Fomapan at 24 degrees for just over 4 minutes.
But
: I would only subject the Fomapan to 24 degrees on a trial basis. Consequently, I would rely on the temperature/development time curves previously included in Ilford instructions, lower the processing temperature to 20 degrees and extend the initial development time accordingly.
Final step: The time calculated so far applied to ISO 200/24 DIN. For a nominal sensitivity of ISO 100/21 DIN, I would shorten the time slightly. A rough guide, based on known times for ‘my’ process, would be a good quarter of an hour shorter.
It is best to use a film strip with a series of exposures comprising perhaps five or six shots of a subject with unproblematic contrast. I would underexpose and overexpose in whole stops, from two stops underexposed to two stops overexposed.
On the subject of
the bleach bath
:
With the potassium permanganate bleach bath, after a few mishaps I started taking the film out of the can and checking it immediately after draining. It should be lemon-yellow.
To be clear: there must be no more stool-coloured... er, nasty black-brown patches visible.
If there are still some there – don’t panic! You could then continue bleaching for a few more minutes – and during the trial phase, I’d try that first.
Often, however, the Bleach bath is spent. In that case, put the film back in the canister, calmly prepare a fresh Bleach bath and bleach for another four or five minutes. So far, this has always sorted things out, and I’ve been able to proceed with the fixing and clearing baths.
For the first attempt with the Fomapan R100, I’d perhaps start with the time for the Adox Scala 50: 4 minutes, if I’m not mistaken.
If that hasn’t been enough upon checking, see above: perhaps extend it by two minutes.
By the way: one can read that, chemically speaking, it’s hardly possible to bleach for too long. That matches my experience. However, I would keep the bleaching time to a minimum when dealing with a sensitive emulsion.
The Rollei infrared film is a prime example: it must be treated like a raw egg – otherwise the coated layer will peel off :flushed-face: . Rinse and handle with care, and above all, do not bleach for too long.
You can tell that the permanganate bleach bath is finished at the latest during the subsequent rinsing: when the pink colour of the water poured out of the can starts to fade noticeably sooner than with a fresh bleach bath.
In my practice (Jobo Tank 1510, approx. 230 ml of liquid with the can constantly rotated by hand during the baths), it is still faintly visible with fresh Bleach bath after the second can filling for rinsing (tipping 10 times each). With used Bleach bath, it has already completely disappeared.
