How does chemicals affect development times?

pkr1979 · Mar 28, 2022

Hi all,

How does the amount of metol, sodium sulphite, hydroquinone, sodium carbonate, potassium bromide, and sodium hydroxide affect development time?

I ask becuase I'll try Orwo 842 (replacing phenidone with metol) instead of Ilford PQ Universal. They time I used with PQ was at 24 degrees celsius for 10 minutes. I assume this is aprox 14:30 if developed at 20 degrees celsius.

The film developed was Tmax400 (at about 160 ISO) and the time is for first development in reversal processing.

The Orwo recipe is here: http://lostlabours.co.uk/photography/formulae/developers/rev_filmotec.htm
Note that Im intending to use the second developer as first developer (meaning omitting the thiocyanate).

Here is the PQ recipe: http://lostlabours.co.uk/photography/formulae/developers/devID62.htm
(UPDATE: I used the concentrated stock diluted 1:5)

I get that assuming development time isnt an exact science... but I figured Id try 14:30 at 20 degrees celsius as this have given good results with PQ. But, are there components in the Orwo recipe that differs to such an extent from the PQ recipe I should consider reducing or prolonging the development time some?

Cheers
Peter

albada · Mar 28, 2022

I believe main factors that determine development time are:
- temperature.
- pH (amount and kind of alkalis). carbonate and hydroxide will have a large effect.
- amount of each developer (metol, HQ), and their ratio.

From my investigation, it seems development time should be decreased by 8.8% for each degree (C) rise in temperature.
For the other factors, experimentation must be used to determine dev time.

pkr1979 · Mar 28, 2022

The Orwo recipe contains much more hydroxide, and more carbonate (but no benzo). In which direction will this push the development time?

mohmad khatab · Mar 28, 2022

I love Oslo.. my dear
I advise you to declutter these idiotic formulas.

I respect the mentality of German scientists very much, and I trust their accuracy.
The attached format, I used it with all kinds of Ilford films and it worked with great success..
I do not like re-exposure using a lamp, I do not trust this method at all, so I used a re-exposure solution for a minute and a quarter of a temperature of 38 degrees Celsius, and these are its components.
Reversal solution
Calgon ………………………….3.0 g
Stannous chloride dihydrate 1.0 g
p-aminophenol………………..0.1 g
Sodium hydroxide ………………8 g
Glacial acetic acid…………. 15 mL
Water to make 1,000 mL
pH 6.00
Of course I replaced Phendion with Metol;in a ratio of 1:11 and not 1:10 as is the case, which means I used 2.2 grams of Metol and everything works fine,

Raghu Kuvempunagar · Mar 29, 2022

Just curious to know why you're thinking of using Orwo 842 second developer as your first developer? What is wrong with Orwo 829 first developer?

pkr1979 · Mar 29, 2022

829 contains thiocyanate, 842 does not. Thats the only difference. I dont want to use thiocyanate.

Don_ih · Mar 29, 2022

pkr1979 said:
I dont want to use thiocyanate.

Omitting thiocyanate from the first developer may result in muddy slides.

As for development times, the PQ Universal recipe uses a lot of benzo in the stock recipe. Benzo, in my experience, slows overall development (but slows shadow development more). You'll need to test to get a time for the Orwo recipe - it's too different from the PQ one.

Raghu Kuvempunagar · Mar 30, 2022

Don Heisz said:
Omitting thiocyanate from the first developer may result in muddy slides.

Not only that, the presence of Thiocyanate in the first developer affects grain, contrast, DMax, speed and sharpness of the positives, at least for films that have not been specifically designed for reversal processing.

pkr1979 · Mar 31, 2022

Ive never had any luck with neither thiocyanate or thiosulfate. I just developed TMY2 in 842 replacing the phenidone with metol and it looks very good at 200 ISO for 12 minutes (20 degrees). Im probably trying other ISOs too at both shorter and longer times. Im pretty close to what Im looking for... Id like to warm up the image a tiny and have to figure out how to do that.

Don_ih · Mar 31, 2022

pkr1979 said:
Ive never had any luck with neither thiocyanate or thiosulfate. I just developed TMY2 in 842 replacing the phenidone with metol and it looks very good at 200 ISO for 12 minutes (20 degrees). Im probably trying other ISOs too at both shorter and longer times. Im pretty close to what Im looking for... Id like to warm up the image a tiny and have to figure out how to do that.

Are you talking about using it to develop the film to a negative or to a positive? Thiocyanate in a first developer for making positives is recommended - not at all recommended to just develop negative film.

RalphLambrecht · Mar 31, 2022

pkr1979 said:
Hi all,

How does the amount of metol, sodium sulphite, hydroquinone, sodium carbonate, potassium bromide, and sodium hydroxide affect development time?

I ask becuase I'll try Orwo 842 (replacing phenidone with metol) instead of Ilford PQ Universal. They time I used with PQ was at 24 degrees celsius for 10 minutes. I assume this is aprox 14:30 if developed at 20 degrees celsius.

The film developed was Tmax400 (at about 160 ISO) and the time is for first development in reversal processing.

The Orwo recipe is here: http://lostlabours.co.uk/photography/formulae/developers/rev_filmotec.htm
Note that Im intending to use the second developer as first developer (meaning omitting the thiocyanate).

Here is the PQ recipe: http://lostlabours.co.uk/photography/formulae/developers/devID62.htm
(UPDATE: I used the concentrated stock diluted 1:5)

I get that assuming development time isnt an exact science... but I figured Id try 14:30 at 20 degrees celsius as this have given good results with PQ. But, are there components in the Orwo recipe that differs to such an extent from the PQ recipe I should consider reducing or prolonging the development time some?

Cheers
Peter

I'm afraid there is no easy answer for this. Reactions and interactions between developer chemicals very complex in the best determined by a test.

pkr1979 · Mar 31, 2022

To a positive. I get better results omitting the thiocyanate.

Don_ih · Mar 31, 2022

pkr1979 said:
To a positive. I get better results omitting the thiocyanate.

Well, the large amount of potassium bromide (6g/l) probably restrains enough of the base fog without thiocyanate. Maybe the thiocyanate in that developer is overkill, anyway.

mohmad khatab · Mar 31, 2022

pkr1979 said:
Ive never had any luck with neither thiocyanate or thiosulfate. I just developed TMY2 in 842 replacing the phenidone with metol and it looks very good at 200 ISO for 12 minutes (20 degrees). Im probably trying other ISOs too at both shorter and longer times. Im pretty close to what Im looking for... Id like to warm up the image a tiny and have to figure out how to do that.

This guy really surprised me...
I read his article hours ago and am seriously considering applying his method. But I don't currently own a D11 developer, so
The method does not need thiocyanate or thiosulfate.
I do not know

pkr1979 · Mar 31, 2022

Ive tried D-11. Its not that great for TMY2.

Don_ih · Mar 31, 2022

mohmad khatab said:
This guy really surprised me.

The "Post in Lightroom" may be a little important.

Raghu Kuvempunagar · Mar 31, 2022

Don Heisz said:
Well, the large amount of potassium bromide (6g/l) probably restrains enough of the base fog without thiocyanate. Maybe the thiocyanate in that developer is overkill, anyway.

Bromide in the first developer primarily affects DMax of the positive by suppressing the fog in the negative silver image but it does nothing to DMin (to give clear highlights). One key function of Thiocyanate in reversal processing is to get clear highlights. So Bromide is not truly a substitute for Thiocyanate, functionally.

Don_ih · Mar 31, 2022

Raghu Kuvempunagar said:
One key function of Thiocyanate in reversal processing is to get clear highlights.

I don't see how a solvent could get clear highlights in that way, since highlights in the slide would be high-density in the negative. That would be the job of the high amount of carbonate in the first developer, in conjunction with the high amount of hq.
Developed to dmax in the negative equals dmin in the positive. No?

pkr1979 · Mar 31, 2022

Thiocyanate/thiosulfate clears highlights but kills midtones. Extending first developer time preserves midtones and clears highlights.

Raghu Kuvempunagar · Apr 1, 2022

pkr1979 said:
Thiocyanate/thiosulfate clears highlights but kills midtones. Extending first developer time preserves midtones and clears highlights.

Why only the midtones? Thiocyanate/Thioshulphate can kill the entire positive image if used in excess. After all, any first developer containing a halide solvent is a monobath. The larger the concentration of the halide solvent in the first developer and/or the longer the first development, the greater the chances that the halide solvent eating up more halides than ideal. So the trick is to tune the concentration of the halide solvent to get clear highlights while not wiping out midtones. Anyway, since you said you're already getting the results you like without halide solvent, this discussion is moot.

Raghu Kuvempunagar · Apr 1, 2022

Don Heisz said:
I don't see how a solvent could get clear highlights in that way, since highlights in the slide would be high-density in the negative. That would be the job of the high amount of carbonate in the first developer, in conjunction with the high amount of hq.
Developed to dmax in the negative equals dmin in the positive. No?

Please read Chapter 7, "Reversal Processing of Black-and-White Materials" in Vol 2 of MODERN PHOTOGRAPHIC PROCESSING by Grant Haist. It answers all your questions and provides excellent technical insight into the role played by Thiocyanate in B&W reversal processing. PDF of the book should be available online or with some members.

Don_ih · Apr 1, 2022

Raghu Kuvempunagar said:
Please read Chapter 7, "Reversal Processing of Black-and-White Materials" in Vol 2 of MODERN PHOTOGRAPHIC PROCESSING by Grant Haist. It answers all your questions and provides excellent technical insight into the role played by Thiocyanate in B&W reversal processing.

Or you could summarize here. This is a discussion, isn't it?
Such a summary would be: the thiocyanate clears highlights by removing undeveloped silver from areas of greatest density in the negative development stage, so that amount of silver cannot be reversed upon positive development.

How does chemicals affect development times?

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