Dektol....same as D72?

[tony lockerbie]

I usually buy Dektol when I can, but this is not always convenient, so I mix up D72 instead. I guess the question is....are they the same? Not that it matters too much, just curious.

 

[Ian Grant]

Yes, the same. Kodak publications with D72 say that it's available a s a packaged developer, without giving the name.

There's two published versions, virtually identical, the most commonly published has the weights rounded to the nearest gram

Ian

 

[Anscojohn]

It is my understanding that the stuff one finds in a Dektol package is different somewhat from D-72; but that this difference is in the sequestering agents bonded to the varius constituents so that they all dissolve in the proper order. In addition, I believe there might be some kind of water conditioners incorporated as well.
For myself, I have always considered Dektol and D72 direct equivalents; just that Dektol is more convenient to mix up, that's all.

 

[Mahler_one]

How about Zone vi developer? Is such also a variant of Dektol John?

Ed

 

[Photo Engineer]

Dektol = D72 + a sequestering agent (at one time Calgon, then Quadrofos and now.... Dequest? IDK)

The sequestering agent has nothing to do with the order of dissolution of ingredients, nor is it bonded to anything. It is just another part of the mix.

The developing agents and the alkali are encapsulated in two different capsules of bonding agents which separate and protect the developing agents from the alkali. When they hit water, the "capsules" all dissolve and form a uniform mixture. The mix is packed under an inert gas.

Neither the sequestering agent, nor the encapsulating material affect development properties unless you mix D72 using very hard water. In that case, you may get some sludge or a fine precipitate.

If the formula for Zone VI = D72 then they are equal.

PE

 

[tbm]

I have never used Dektol for paper development. What appearance does it give a darkroom print--cold or neutral blacks?

 

[Ian Grant]

Kodak say Neutral to Cold.

There is also liquid Dektol, which is the same as Polymax T developer, this has been re-formulated in recent years to use Potassium Sulphite, Potassium Carbonate & Potassium Hydroxide in place of Sodium Sulphite and Sodium Carbonate, this a allows a more concentrated solution, and cuts costs. Ilford have done the same with their Liquid paper developers.

Ian

 

[pgomena]

If I remember correctly, Fred Picker advertised his Zone VI developer as having no sequestering agents. It is/was packaged in two separate packages that are mixed with water. What the exact ingredients and proportions are, I have no idea. Is it close to Dektol, I'd say yes. The differences are/were small. Noticeable, yes, but not night and day.

Peter Gomena

 

[Ian Grant]

The truth is most companies made very similar developers, so there's Ilford & Agfa (inc Ansco.Gaf & Orwo/Calbe) developers that are equivalent to Dektol/D72.

Many of Kodak's early developers came either from companies they took over, like Nepera (Velox), Wratten etc or were clones of European developers, many of which were in publications like the British Journal of Photography. Much early work on developers was done by companies like Lumiere & Hauff.

Ian

 

[Photo Engineer]

I would have to add that virtually every formula that Kodak used or produced but did not originate was published in some manner by Kodak at one time or another. Formulas that originated through internal R&D were never published.

And so we can find Dektol = D72 as an open formula, but Microdol X is not.

PE

 

[Ian Grant]

Formulas that originated through internal R&D were never published.
PE

Not strictly true when the developer was covered by a Patent, like Xtol, HC-110, but of course we can't be 100% sure the Patent version is identical to the final commercial product.

Ian

 

[chriscrawfordphoto]

Kodak originated D76, didn't they? And it was published.

 

[Ian Grant]

Kodak originated D76, didn't they? And it was published.

There were already fine grain MQ Borax developers, so D76 was a derivation balanced specifically for cine films.

Ian

 

[Anscojohn]

How about Zone vi developer? Is such also a variant of Dektol John?

Ed

*******
I don't know. Except that any MQ paper developer is, essentially, D-72(Dektol), as far as I can tell.

 

[Anscojohn]

Dektol = D72 + a sequestering agent (at one time Calgon, then Quadrofos and now.... Dequest? IDK)

The sequestering agent has nothing to do with the order of dissolution of ingredients, nor is it bonded to anything. It is just another part of the mix.

The developing agents and the alkali are encapsulated in two different capsules of bonding agents which separate and protect the developing agents from the alkali. When they hit water, the "capsules" all dissolve and form a uniform mixture. The mix is packed under an inert gas.

Neither the sequestering agent, nor the encapsulating material affect development properties unless you mix D72 using very hard water. In that case, you may get some sludge or a fine precipitate.

If the formula for Zone VI = D72 then they are equal.

PE

******
I stand corrected.

 

[Photo Engineer]

Not strictly true when the developer was covered by a Patent, like Xtol, HC-110, but of course we can't be 100% sure the Patent version is identical to the final commercial product.

Ian

That is exactly the problem.

The Microdol-X formula is probably the most famous, but the HC-110 formula is almost impossible for the small experimenter to reproduce as it requires cylinders of Sulfur Dioxide gas and Hydrogen Bromide gas. Not nice things to store at home.

And, the reactions involved to make it in-situ are messy and dangerous.

I believe that the Xtol patent is also devious based on what Bill Troop and I have discussed regarding this patented formula. And, I know from experience that process chemistry is quite at variance with many patents which seem to disclose all.

Interestingly, the patented formulas will (and of course must) work.

PE

 

[Kirk Keyes]

I thought I heard from you (PE), that Sylvia says the Xtol patent was a "teaching patent" - I took that to mean that the patent for XTOL pretty much disclosed the actual formula. Am I wrong in my interpretation of her comment?

 

[Photo Engineer]

I thought I heard from you (PE), that Sylvia says the Xtol patent was a "teaching patent" - I took that to mean that the patent for XTOL pretty much disclosed the actual formula. Am I wrong in my interpretation of her comment?

All patents must "teach one skilled in the art, the method of operation of the claims of the patent". It does not state that the optimum formula must be disclosed and in fact, the claims give ranges and preferred ranges.

Therefore, you, as a chemist, might make a very good educated guess and I might do even better due to experience, but an average person might be totally lost just by the very definition of the purpose of a patent.

So, what I said to you was the quote above. I believe that Dick and Sylvia would agree.

PE

 

[Ian Grant]

*******
I don't know. Except that any MQ paper developer is, essentially, D-72(Dektol), as far as I can tell.

MQ paper developers can be very varied and differ in their use & effects but they tend to fall into groups.

Normal, like D72 would be: Ilford ID-20, Dupont 53-D, Haloid D1, Agfa 125 plus many more

Contrast Developers: Ilford ID-14, ID-21

Warm Tone: Kodak D52 (Selectol), D32, D166, Agfa Ansco 135,

There are so many variations for special uses that the list is enormous, but the ratios of Metol to Hydroquinone, the Sulphite & Carbonate levels as well as the Bromide are all varied to give different contrasts and image colour, ranging from Blue Black to very warm Red-brown tones and High Contrast to softer working although the softest working developer like Selectol Soft (D165) and ID-3, Adaptol etc are Metol only.

Ian

 

[tony lockerbie]

Wow, thanks for that...the usual wealth of information!

 

[cmacd123]

Published formuals?

I would have to add that virtually every formula that Kodak used or produced but did not originate was published in some manner by Kodak at one time or another. Formulas that originated through internal R&D were never published.

I thought that most of the "chemicals" for the motion picture processes are published. some of them come with warnings about needing a licence to use them commercially.

http://motion.kodak.com/US/en/motion/Support/Technical_Information/index.htm

 

[Photo Engineer]

I thought that most of the "chemicals" for the motion picture processes are published. some of them come with warnings about needing a licence to use them commercially.

http://motion.kodak.com/US/en/motion/Support/Technical_Information/index.htm

This is true.

You can even buy a high level EK license / contract which supplies you with formulas, analytical and other control features and technical support.

At Cape Canaveral we had such support and could call in EK assistance right from the local office in Orlando. We had scratch mix facilities and processed B&W and color MP right there on-site. But, it was essentially an NDA situation in that the information was confidential and only licensed.

This is also done in Hollywood.

PE