Stagirit
Does anyone still have the Rodinal PDF data sheet?
Unfortunately, Agfa has taken it down from the website.
I need the pH values for 1+25 and 1+50, and possibly the processing times for Neopan 400 as well.
Wolf_XL
...I've probably got that lying about somewhere in the lab – I'll have a look this evening.
cfb_de
Hi Stagirit,
here’s the
technical data
sheet
for the software chemicals
. It’s all I’ve got, but maybe it’ll be of some help.
Best regards,
Franz
Stagirit
Thank you very much!
Unfortunately, Agfa’s data sheets don’t include any pH values.
So I’ll use distilled water and hope for the best.
I want to develop a Neopan 400 at its rated speed; if I use the Super Prodol curve, I get 5 3/4 minutes at 20°C.
Is that acceptable?
I usually only develop Neopan in Microdol, but I’ve run out of that stuff.
Wolf_XL
Hello Stagirit,
I don’t have what you’re looking for either – I only have the English-language table, which also lists the 1+100 times. There are no pH values on this table...
Wolfgg
Why are you worrying about the pH level with Rodinal? You only really need to worry about that when developing E6 film, so the colour doesn’t run all over the place.
Stagirit
When I open an ancient bottle that’s been sitting open in the fridge for a year (it wasn’t mine), I prefer to check the pH level.
I always do this when I make my own solutions.
Here’s what I’ve found out:
Alkaline developers such as Rodinal are around 10–11
Fine grain developers such as Microdol are around 6.5
I’ve printed out the data sheets straight away and filed them away – thanks again for that.
piu58
If I open an ancient bottle that’s been sitting open in the fridge for a year (it wasn’t mine), I’d rather check the pH level first.
When I make my own solution, I always do this as a matter of principle.
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Rodinal contains concentrated potassium hydroxide. The concentrate should have a pH of around 13–14 and is likely to break down most test strips and substances.
Stagirit
The pH level is between 10 and 11; the film has been developed and, at first glance, looks very good. I won’t be making prints until the weekend at the earliest.
Wolfgg
However, simply knowing the pH value doesn’t tell you whether the antioxidant in the developer (usually sodium sulphite or potassium sulphite) has managed to keep harmful atmospheric oxygen away from the actual developing agent right until the end. Only a test development can reveal that. But from what I’ve read, you’ve already had success.
Wolf_XL
...well, with Rodinal, I might start to worry if it’d been sitting around for thirty years... ;-)
Stagirit
You can never be absolutely certain. St Murphy’s Law alone puts a stop to that.
I don’t usually work with Rodinal. I prefer to use my own homemade developers.
I’ll take some with me on my next holiday, though, as I want to carry out the Ilford SFX development straight away so it doesn’t sit around for too long.
cfb_de
Hello Stagirit,
As far as the pH value is concerned, I completely agree with Wolfgg and Uwe. If the concentrate really does have a pH of 13, then a pH of around 11 would be expected for a 1:100 dilution.
However, the test strips you appear to be using have an error margin of almost +/-2pH. Unfortunately, the human eye is simply too colour-blind and lacks sufficient contrast to detect this.
But that doesn’t mean much, because the pH value and the oxidation state of the developer substance correlate about as well as the Pope in Rome does with the practical act of procreation.
My Rodinal, which I’ve opened especially for you (it’s been sitting here since 2003), has a pH of 11.9 – just titrated. But that doesn’t mean much either, as significant fluctuations are normal in the technical handling of such products. Still, it’s always nice to be able to take a step back and return to the craft you’ve studied :-)
Regarding Wolf_XL: Thirty-year-old Rodinal, pitch black and sitting on top of the sediment, should actually still be as good as new. Things only get critical at >60 years. And even this bottle, which had been stored in the loft since the late 1950s, was just as good as brand-new R09 – with a significantly lighter colour and consequently less oxidation. I used up the heirloom and sold the empty bottle, complete with the Reich vulture, to Britain. For a tidy sum. Inheritance is sometimes worthwhile even for things that would normally end up in the bin.
Best regards,
Franz
SamuliSchielke
On a completely different note, since we’re on the subject of Rodinal. I’m flying to Egypt this weekend. The specialist lab I’ve chosen there has quite a bit of variation in the black-and-white process, and they only sell developer in 10-litre tanks intended for large-scale labs, which is why I’m taking my own developer with me.
But are you actually allowed to carry something as strongly alkaline as Rodinal on a plane?
After all, it does have the warning ‘corrosive’ on it, and you’re not actually allowed to carry that on a plane. Otherwise, I’ll just use a less aggressive stop bath, but Rodinal would definitely be my first choice.
Incidentally, my 1957 photochemistry handbook claims that undiluted Rodinal has a pH of 12.3.
Samuli
Stagirit
Well, the Rodinal doesn't have to be in the original bottle. :angry:
