Developer question for PE and others

Paul Verizzo · Jul 16, 2008

I've always been intrigued that DK-50 uses equal amounts of Metol and Hydroqinone. I pretty sure I've never seen any other, other than the divided developer formula of Otha Spencer.

Why?

I'm familiar with the works quoted by Haist comparing activity of PQ and MQ developers per varying ratio. IIRC, 1:4 Metol to HQ results in maximum activity, so that's not the reason.

Also the Kodak info on DK-50 says that it might have a staining effect on the negative. ?????

Thanks!

Ian Grant · Jul 16, 2008

Here are one or two other examples of equal amounts of Metol & Hydroqinone used in a formula:

Orwo 17 - 1.5 & 1.5
Foton N1 - 2 & 2
Foton N2 - 2 & 2
Fuji FD22 - 2.5 & 2.5
DK60a - 2.5 & 2.5
Leonar 4a - 3 & 3
Gevaert 221 - 3 &3
Kodak D82 - 14 & 14

and almost

Foton N -1.4 & 1.6
Agfa/Orwo 1 - 5 & 6
Agfa/Orwo 71 - 5 & 6
Agfa/Orwo 36 - 6.25 & 7

So it's quite common and not always for the same reasons. D82 is a High energy developer while many of the others are softer working.

Ian

Terrence Brennan · Jul 16, 2008

Developer question

I use a modification of the Ansco 17M formula, in which the ratio of Metol to Hydroquinone is 1:1.333, as opposed to the original formula, in which the ratio is 1:2. I have also doubled the the amount of sodium metaborate from the original formula, to 4 g/l. I did this because I wanted shorter development times, but found that I was "blowing out" my highlights, hence the reduction by 1/3 in the ammount of hydroquinone.

The Ansco 17M formula may be found here: http://www.digitaltruth.com/techdata/agfa_ansco_17m.php

Photo Engineer · Jul 16, 2008

I guess it was designed with what works best with the rest of the chemistry.

As for staining, I have never heard of that one. Can you give a reference?

PE

df cardwell · Jul 16, 2008

DK-60a used the same amount of M/HQ as DK-50,
increasing the Sulfite and Kodalk. Things happen pretty quickly in this stuff,
but it was formulated in the '30s when processing solution were commonly untempered.
The shorter development times @65˚ were handy.

Paul Verizzo · Jul 16, 2008

Thanks, all!

I guess I hadn't done my homework, should have spent yet more hours in the Photo Lab Index! I should have caught the other Kodaks and Gaevert, but I've never seen formulas for Orwo or Fuji.

PE, the mention of staining is right off of Kodak's site: http://www.kodak.com/global/en/professional/products/chemistry/bwFilmProcessing/dk50.jhtml

But still no answers as to <i>why.</i> Are there any alleged properties for a 1:1 ratio vs a 1:2.5 like D-76? Or 1:4 for maximum activity? (Haist) Or were these concocted out of the gut way back in the thirties when a lot less was understood?

Ian Grant · Jul 16, 2008

The Photo Lab Index is riddled with errors, many of the developers in my database are obscure, so you might not find them easily

It's not so easy to see patterns in Kodak developers whereas Ilford use more standardised quantities. It really helps being able to sort a table of developers in any way you wish, so I just sorted by Metol & Hydroquinone in descending quantities and spotted when the two were the same.

If you assume that a plain Metol developer is relatively soft working, and that there's also an optimum MQ ratio for maximum super-additivity and also higher contrast etc then varying the ratio has an effect on the contrast. It's all a balancing act.

Ian

Ian

df cardwell · Jul 16, 2008

Instead of overthinking this, why not give DK-50 a test drive ? Until it was displaced by HC-110,
it was a standard Portrait and Commercial developer, and still is a lovely thing to soup film in.

120 Plus-X is spectacular in it.

Crawley experimented with a high dilution of DK-50 in a sulfite solution as a convenient acutance developer;
see Troop, and BJP Almanac.

PE: how buffering work with Kodalk developers ?

Alan Johnson · Jul 16, 2008

Here's an explanation with an outside chance:
In the thread below, Ryuji notes that metol and hydroquinone have mutual inhibition of the aerial oxidation reaction and there is an optimum M:Q ratio that minimises oxidation as a whole (he does not say what it is).
(there was a url link here which no longer exists)

Photo Engineer · Jul 16, 2008

Paul Verizzo said:
PE, the mention of staining is right off of Kodak's site: http://www.kodak.com/global/en/professional/products/chemistry/bwFilmProcessing/dk50.jhtml

Well, on that page you reference, it says that the image tone is slightly brownish. That merely refers to the image and not a stain. In fact, that is probably the reason for the ratios of the developing agents, to give a warm toned negative image. IDK for sure.

A stain is not the same as getting a warm toned image from the silver itself.

PE

Photo Engineer · Jul 16, 2008

df cardwell said:
PE: how buffering work with Kodalk developers ?

I'm not sure I follow this question. Sorry.

I can try an answer. Kodalk is a borate buffer that has good buffer capacity and ability on the alkaline side between about pH 9.5 and 10.5. It is used in a number of developers, but its use is declining due to the toxicity of borate salts to citrus fruit trees.

PE

Ian Grant · Jul 16, 2008

Interesting point Ron, Kodalk is fairly unique to Kodak formulae, although Fuji & Konica, and also Crawley & Paul Lewis (Mytol) each use it in one of their formulae.

Even plain Borax is a good weedkiller

Ian

Photo Engineer · Jul 16, 2008

Ian;

Agfa used Ersatz Kodalk as buffer in their formulas during the war. I would have to look it up though, as I cannot remember what it was.

PE

Keith Tapscott. · Jul 16, 2008

Photo Engineer said:
I'm not sure I follow this question. Sorry.

I can try an answer. Kodalk is a borate buffer that has good buffer capacity and ability on the alkaline side between about pH 9.5 and 10.5. It is used in a number of developers, but its use is declining due to the toxicity of borate salts to citrus fruit trees.
PE

There aren`t many citrus fruit trees where I live. Seriously though, what would photo-chemist use as an alternative to the mild borate alkalis if photographic companies were forced to find an alternative?

Paul Verizzo · Jul 16, 2008

Yuppers!

Ian Grant said:
If you assume that a plain Metol developer is relatively soft working, and that there's also an optimum MQ ratio for maximum super-additivity and also higher contrast etc then varying the ratio has an effect on the contrast. It's all a balancing act.

Ian

Ian

Meese, not Haist, presents other's research on maximum activity for MQ and PQ developers on pages 118-119. The MQ curve is rather flat like a French curve for those who remember what that is. There isn't a whole lot of difference between the 1:4 molar weight ratio and its peak activity and more equal weights like our 1:1 gram weight here. However, the curve for PQ is more like a lopsided sharp letter V, and the peak activity is at 1:9 molar. Most PQ formulas, however, use ratios around 1:24.

My notes show some old calculations for molar vs. gram ratios M:Q. I encourage anyone to double check me on this, I ain't no math whiz. The standard developer used in the test is a 2.81 centimoles/liter with a 10.36 pH. Again, if I did the math right, that's about double that of standard developers and dilutions.

In an MQ developer, the time to reach standard gamma is fastest with a 1:9.4 weight ratio, two minutes. ID-72 and D-72 use a gram weight ratio of 1:4 but the time to gamma is barely different. D-76 is 1:2.5 and is of minimal increase over that. And last, with a 1:1 ratio the time finally is noticably slower, close to 3 minutes.

I hope this confuses things, I mean, offers some insights.

Tom Hoskinson · Jul 16, 2008

Paul Verizzo said:
I guess I hadn't done my homework, should have spent yet more hours in the Photo Lab Index! I should have caught the other Kodaks and Gaevert, but I've never seen formulas for Orwo or Fuji.

PE, the mention of staining is right off of Kodak's site: http://www.kodak.com/global/en/professional/products/chemistry/bwFilmProcessing/dk50.jhtml

But still no answers as to <i>why.</i> Are there any alleged properties for a 1:1 ratio vs a 1:2.5 like D-76? Or 1:4 for maximum activity? (Haist) Or were these concocted out of the gut way back in the thirties when a lot less was understood?

Paul, I could not find any reference to stain in the Kodak Reference you supplied. I did find: "Produces a slightly brownish image tone." So does Microdol-X but that doesn't mean it is image stain (or overall stain - for that matter). It is well known that Hydroquinone can produce image stain that is proportional to exposure (see Haist, Gainer and others). Hydroquinone stain, PyroGallol stain and Catchcol Stain can all be prevented with adding sufficient Sodium Sulfite to the developer solution.

Photo Engineer · Jul 16, 2008

Keith Tapscott. said:
There aren`t many citrus fruit trees where I live. Seriously though, what would photo-chemist use as an alternative to the mild borate alkalis if photographic companies were forced to find an alternative?

Kodak was converting developers from Kodalk to Carbonate when I was working on these types of projects. Thus the P-122 developer went from Kodalk to the Carbonate based EP-3 developer with no change in pH.

This can generally be done as well with TEA, or TEA DEA mixtures or TEA and Carbonate. There will be image tone changes with B&W, but this can be fixed by tweaking other addenda.

PE

dancqu · Jul 16, 2008

Photo Engineer said:
Kodak was converting developers from Kodak to Carbonate
when I was working on these types of projects. Thus the
P-122 developer went from Kodalk to the Carbonate
based EP-3 developer with no change in pH. PE

From Kodak? Kodalk. That and ph. Hydroquinone becomes
active somewhere around the kodalk carbonate ph. Being
that the case it will up the contrast. Given an activating
ph hydrodquinone will in it's porportion to metol increase
contrast. Common knowledge. So, at a 1:1 ratio not
so contrasty; more nearly metol only. Dan

Paul Verizzo · Jul 16, 2008

"Produces a slightly brownish image tone."

Tom Hoskinson said:
Paul, I could not find any reference to stain in the Kodak Reference you supplied. I did find: "Produces a slightly brownish image tone." So does Microdol-X but that doesn't mean it is image stain (or overall stain - for that matter). It is well known that Hydroquinone can produce image stain that is proportional to exposure (see Haist, Gainer and others). Hydroquinone stain, PyroGallol stain and Catchcol Stain can all be prevented with adding sufficient Sodium Sulfite to the developer solution.

That's what I was calling a stain. Should I not?

I guess the relatively low sulfite in DK-50 "let's" it happen sometimes.

Just a note of curiosity.

Tom Hoskinson · Jul 17, 2008

Paul Verizzo said:
That's what I was calling a stain. Should I not?

I guess the relatively low sulfite in DK-50 "let's" it happen sometimes.

Just a note of curiosity.

Maybe, and an easy way to find out is to bleach the silver out of a neg post development and see if the "stain" is still there afterwards. Also, does the "stain" block light? Transmission densitometry can answer that question.

Photo Engineer · Jul 17, 2008

Kodak is referring to the fact that DK50 produces a warm toned silver image with some films just as some papers produce warmer tones in certain images. The image thus appears brownish.

Whether it is a staining developer or not is harder to determine. Bleaching the silver image leaves behind a faint brown image in almost every case I have tested. Often this is a mixture of Silver Sulfide and other complexes in the coating or is true "stain" produced by the developer.

If this brown-yellow imagewise stain can be removed by treatment in acidic fixer, then it is what we consider having been produced by a mildly staining developer.

PE

Igor Savchenko · Jul 29, 2008

Agfa's Ersatz Kodalk

Photo Engineer said:
Agfa used Ersatz Kodalk as buffer in their formulas during the war. I would have to look it up though, as I cannot remember what it was.

PE

Could you please look for that in your notes or let me know a source where I can search myself?
Thanks.

Photo Engineer · Jul 29, 2008

In den Begiebezustatze ist Borax-Ersatz je nach Saure bestimmung oder Borax mit Natrium Carbonate.

During the war, Agfa could not get Borax from the US easily so they made a substitute. This quote above is directly from what I copied from an Agfa formula many years ago. It was published (AFAIK) in the FIAT reports.

I hope I got that right.

PE

Tom Hoskinson · Jul 30, 2008

Photo Engineer said:
Kodak is referring to the fact that DK50 produces a warm toned silver image with some films just as some papers produce warmer tones in certain images. The image thus appears brownish.

Whether it is a staining developer or not is harder to determine. Bleaching the silver image leaves behind a faint brown image in almost every case I have tested. Often this is a mixture of Silver Sulfide and other complexes in the coating or is true "stain" produced by the developer.

If this brown-yellow imagewise stain can be removed by treatment in acidic fixer, then it is what we consider having been produced by a mildly staining developer.

PE

Yes, and if it is a stain image formed by Hydroquinone, Pyrocatechol, Pyrogallol or Amidol, it will block UV light and some other frequencies.

Terrence Brennan · Jul 30, 2008

Metaborate

Ian Grant said:
Interesting point Ron, Kodalk is fairly unique to Kodak formulae, although Fuji & Konica, and also Crawley & Paul Lewis (Mytol) each use it in one of their formulae.

Even plain Borax is a good weedkiller

Ian

AGFA-Ansco also promoted metaborate formulas, such as Ansco 17M, which was a metaborate version of Ansco 17. Ansco 17M had 2.0g/l of sodium metaborate, to replace 3.0g/l of borax in the Ansco 17 formula. There was also Ansco 48M, which had 10.0g/l of sodium metaborate, with correspondingly shorter times than those recommended for Ansco 17M.

Check out these links: Dead Link Removed and http://www.digitaltruth.com/techdata/agfa_ansco_48m.php

Developer question for PE and others

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