DK-76.

[Keith Tapscott.]

What is the purpose of this developer compared to the standard D-76/ID-11 developers? Is (was) it used for processing special purpose films?
Perhaps P.E. might know the history of this process.

http://www.digitaltruth.com/techdata/dk76.php

 

[Ian Grant]

DK76b is another variant with Sodium Metaborate, so are FD22 (Fuji) and KD22 (Konica).

Over the years there have been numerous variations of D76 from Kodak, at least 8, and Afga, Fuji, Konica, Orwo produced their own variations. Basically they were all trying to find the best buffering system.

Ian

 

[Mick Fagan]

Keith, I'm not a chemist, but that is a stock standard D76 formula as far as I can ascertain. I mix that formula at least once a month.

Page 206 of Developing, by Jacobson & Jacobson eighteenth edition 1976 and reprinted 1980, lists this as one of 14 fine grain developer formulae.

Borax is another name for Sodium Metaborate, others will correct me if I'm wrong, but another name is Kodalk which is a trade name for the same stuff from Kodak.

I'm assuming the K in the developer description possibly refers to Kodak, maybe?

Mick.

 

[Mick Fagan]

Ian, obviously I'm up late and you're up early, I would like your comments on my posting

Mick.

 

[df cardwell]

Back in the day, Kodak tried to exploit the advantages Kodalk had over Borax.

From " Elementary Photo Chemistry", EKC, 1941.

Page 94 [Formula D-76]

"A faster working developer can be obtained by increasing
the quantity of borax. By increasing the borax quantity 10 times
(... from 2 grams to 20 grams per liter), the development will be about one-half that of regular D-76. If a still more active developer is required, replace the borax in D-76 with 10 times as much Kodalk (... 20 grams per liter). With this concentration of Kodalk the development time will be one-quarter that of regular D-76."

This might have been handy of you were processing at lower temps. And there WAS a war on. I think Suzuki mentions this formula.

Using 2 grams of Kodalk might suggest the desire to try a different buffer than Borax in the original formula, but according to Suzuki, Borax is the better buffer. All the derivations of D-76 exchange benefits for problems, and simply shift the balance of the original formula. Using the Haist 'no borax' version seems to be the best choice today: storage isn't an issue as few of use are running D-76 in big tanks !

In other words, I haven't got a clue.

 

[Ian Grant]

Ian, obviously I'm up late and you're up early, I would like your comments on my posting
Mick.

DK76 isn't specifically listed by Jacobson However he does list D76 and the replenisher as using Borax or Sodium Metaborate (Kodalk). Borax is Sodium tetraborate. Kodalk can be substituted by using Borax & Sodium Hydroxide, For every 10g of Kodalk, add 1.3g sodium hydroxide and 6g Borax. That's always worked fine for me in various formulae.

On page 205 Jacobson states if Kodalk is used the developer is more active & films requires shorter dev times.

Ian

 

[Snapshot]

On page 205 Jacobson states if Kodalk is used the developer is more active & films requires shorter dev times.

Ian

The formula I have for DK-76 has 2.0 grams of sodium metaborate but doesn't indicate a decrease in development time. By what factor do you decrease development time due to the increased activity? Also, I'm wondering does the pH increase enough to activate the hydroquinone?

 

[Ian Grant]

Using 2 grams of Kodalk might suggest the desire to try a different buffer than Borax in the original formula, but according to Suzuki, Borax is the better buffer. All the derivations of D-76 exchange benefits for problems, and simply shift the balance of the original formula. Using the Haist 'no borax' version seems to be the best choice today: storage isn't an issue as few of use are running D-76 in big tanks !

In other words, I haven't got a clue.

The attempts to improve D76 are really to improve long term stability in a tank / replenishment system.

For many years I processed all my films in Kodak Deep tanks, there were 3 photographers using the same ID-11 (D76) and stability & consistency were important. We always knew when the developer was on the turn as activity increased and negatives became slightly thinner but with more contrasty.

I've always replenished developers even without deep tanks, starting with Microphen back in the late 60's through ID-11, Adox Brax MQ to Xtol. The results are more like using the same developer at about 1:2. Better grain, tonality & sharpness.

Ian

 

[df cardwell]

The attempts to improve D76 are really to improve long term stability in a tank / replenishment system.

Which is why Kodak came up with D-23.

And Polydol.

And Xtol.

Big fan, here, of replenished systems.

 

[Photo Engineer]

The problem with any tank of developer is that the pH will drop due to aerial oxidation and absorption of carbon dioxide from the air. The term "pH" must be separated from the term "buffer capacity". So, while the pH of 10 g /l of Kodalk and 2 g / L of Kodalk might be the same (or nearly so), the buffer capacity of the 10 g/l solution is 5x higher and will develop more rapidly.

It will also maintain activity longer due to higher buffer capacity against atmospheric carbon dioxide.

I have not looked up this specific developer, nor any history but what I can remember is consistant with the fact that Kodak twiddled developer formulas in the early days, but since about 1970 or thereabouts, formulas were stable and unchanged except for new items on the shelf like XTOL, and the change from Calgon to Quadrofos as sequestrant or anti sludging compound.

PE

 

[Keith Tapscott.]

I have not looked up this specific developer, nor any history but what I can remember is consistant with the fact that Kodak twiddled developer formulas in the early days, but since about 1970 or thereabouts, formulas were stable and unchanged except for new items on the shelf like XTOL, and the change from Calgon to Quadrofos as sequestrant or anti sludging compound.

PE

Thanks to everyone who replied. I am aware of many variants of D-76 and DK-76 is briefly mentioned on Ryuji Suzuki`s site on D-76 history. Mick, Borax is sodium tetraborate and sodium metaborate is `Kodalk`hence the `K` which is a little more active and used in DK-76, everything else is identical. I am wondering if DK-76 was specifically mixed and used for processing certain types of scientific plates and emulsions?

 

[df cardwell]

Back in 'the day', I worked in the darkroom of a portrait studio that used DK-50 in the tanks,
and Ektonal (a Kodalk developer) in the trays. I've wondered more than once since then
how both the film and prints seemed so consistent day to day, and week to week, month to month.

Maybe it was more than my innocence, that the Kodalk developers did what EKC intended them to do,
and that my boss knew what he was doing .

 

[Photo Engineer]

There are many "economy" versions of developers on the market that do the job when mixed, but when put to the test of hard usage, they fail. Kodak wanted stability for the amateur and the pro.

PE

 

[dancqu]

Borax is another name for Sodium Metaborate,..

There are three borates; orthoborate, metaborate, and
tetraborate. The later being borax. Dan

 

[Mick Fagan]

Yep, I should have walked out to the darkroom, instead of relying on my retained knowledge, many thanks for the corrections.

Ian I have now read the previous page, it's clearer now in the light of a new day.

Mick.

 

[Christiaan Phleger]

Ah, loved that Ektonal. Great stuff, really wish I could find the formula, been looking for years. Its got Na Hydroxide, Kodalk, Metol and HQ, Na Sulfite of course, but the exact % are a mystery.

 

[gainer]

Was DK-76 one of the ways to counteract the initial "surge" of activity of D-76?

 

[nworth]

...
Borax is another name for Sodium Metaborate, others will correct me if I'm wrong, but another name is Kodalk which is a trade name for the same stuff from Kodak.

I'm assuming the K in the developer description possibly refers to Kodak, maybe?

Mick.

Borax ans sodium metaborate are quite different chemicals, sodium metaborate being considerably more alkaline and producing more active developers. Developing times for D-76 with sodium metaborate (Kodalk) substituted for borax will be shorter and the grain will be greater. This is similar to Agfa 17 vs. Agfa 17M.

Kodak developers are named either D-nn or DK-nn (and sometimes SD-nn for "special" formulas). I don't know the rationale behind the different names or if the numbering is a different series for the D and DK names.

 

[Keith Tapscott.]

Was DK-76 one of the ways to counteract the initial "surge" of activity of D-76?

Perhaps to speed up the development times of the thick emulsion films around 1930`s onwards?:confused:

http://photo.net/black-and-white-photo-film-processing-forum/00QCLS

 

[Photo Engineer]

All developers with HQ and relatively low buffer capacity suffer a surge. Basically, HQ decomposes during mixing to form the HQ-monosulfonate and sodium hydroxide, and the pH goes up and then it drifts down as the solution equillibrates. There is a complete description of this in both Mees and in Haist. This effect is also seen in Dektol.

PE

 

[dancqu]

Was DK-76 one of the ways to counteract the
initial "surge" of activity of D-76?

That surge is the result of the hydroxyle ion
produced as a by product of the oxidation of
hydroquinone. You well know the result of
hydroxyle ion on borax. For those who
do not, the result is metaborate.

The ph of sodium metaborate is well below
that of sodium hydroxide although higher
than sodium tetraborate. Dan