In one of the old patents on the technology for the production of powder compositions of developers, I read that in order to improve solubility and keep them dry, the developing substances are preliminarily “activated” in various mixtures of reagents. For example, in a mixture of sulfite and regular sugar. Then the prepared solution is dried and the resulting powder is used in the preparation of the final product.@Kino
Now, regarding the "activation" of hydroquinone, I really don't understand what they mean from what you said. Metol and hydroquinone is a superadditive combination and hydroquinone certainly works in D76. Perhaps they mean the "activation" of quinone, an oxidised form of hydroquinone, by converting it to hydroquinone monosulfonate, which is a mild development agent, but they certainly don't need to add anything special to D76 to do so. Sodium sulfite, which is already present in D76 takes care of this.
@Kino
The formula used by Kodak in their prepackaged D76 is probably a better buffered one. Using a combination of compounds, one can make a pH buffer that will resist, to some extent, pH swings. D76d is a better buffered variant that uses a mix of borax and boric acid instead of just 2g/l borax. It is rumored that this is close to what you get when buying D76.
Now, regarding the "activation" of hydroquinone, I really don't understand what they mean from what you said. Metol and hydroquinone is a superadditive combination and hydroquinone certainly works in D76. Perhaps they mean the "activation" of quinone, an oxidised form of hydroquinone, by converting it to hydroquinone monosulfonate, which is a mild development agent, but they certainly don't need to add anything special to D76 to do so. Sodium sulfite, which is already present in D76 takes care of this.
There's some extra reading here, saved from the now-defunct silvergrain web site of Ryuji Suzuki:
https://web.archive.org/web/20090530193028/http://silvergrain.com/labs/D-76
It's often forgotten that the way D76 is used today is often quite different to it's original origins as a replenished D&P and motion picture developer. It was never designed for amateur use diluted at 1+1 or 1+3.
Changes in buffering improved it's use at 1+1 and 1+3 making it less prone to variations in water supply. The major issue with all Metol & MQ based film developers and replenishment is Bromide build up which suppresses Metol activity meaning you have to use a bleed system of replenishment. This was overcome by Ilford in the late 1950's who introduced Autophen a Phenidone PQ variant of ID-11/D76 for D&P/Photo finishing labs, this needed top up replenishment which is far more economic and not prone to issues with Bromide build up.
Kodak had experimented with Phenidone and Ascorbic acid developers but were prevented from commercial use by a Swedish company's Patent and were only able to introduce Xtol when this expired.
Ian
I think it was @Photo Engineer in this forum who said that Kodak make a blend of chemicals that go in a developer sachet and they cover the development agents used with sulfite. This should reduce oxidation of these agents drastically while the product stays on the shelf.In one of the old patents on the technology for the production of powder compositions of developers, I read that in order to improve solubility and keep them dry, the developing substances are preliminarily “activated” in various mixtures of reagents. For example, in a mixture of sulfite and regular sugar. Then the prepared solution is dried and the resulting powder is used in the preparation of the final product.
Perhaps this is precisely what was meant by the term "activation of hydroquinone."
In one of the old patents on the technology for the production of powder compositions of developers, I read that in order to improve solubility and keep them dry, the developing substances are preliminarily “activated” in various mixtures of reagents. For example, in a mixture of sulfite and regular sugar. Then the prepared solution is dried and the resulting powder is used in the preparation of the final product.
Perhaps this is precisely what was meant by the term "activation of hydroquinone."
The book praises XTOL.
Kodak had experimented with Phenidone and Ascorbic acid developers but were prevented from commercial use by a Swedish company's Patent and were only able to introduce Xtol when this expired.
They don't seem to appreciate the Jobo process.
Still D-76 is classic stuff with some particular aesthetic footprint, of course grain and tonality can also be worked in the processing, but straight D-76 results are nice and one may want exactly that, D-76 is loved by many and a reason has to be there.
Not a surprise, while rotary processing is flawless and consistent it only allows a single kind of processing: continuous agitation. If one wants some kind of compensation from agitation pattern then rotary cannot do that. If one wants adjacency effects then rotary cannot do that also.
And also rotary tends to mix more air's oxygen in the chem, which may have some side effects sometimes.
But of course rotary is great if one just wants continuous agitation.
IMO Troop/Anchell tend to say thinks like they are, sometimes generating controversy about religious matter, and sometimes they also make statements that are debatable, but anyway DCB and FDC are a very, very good reference!!
I'm grateful because I've learned a lot with their books.
This at first suggests a corollary that machine processing is for precise, repeatable development that can be banal and that hand processing is artisanal and inherently variable,
Restraining the development to a known, fixed variable allows some people more flexibility prior to exposure, where as hand processing allows both prior and post exposure manipulation possibilities.
If you dissolve more than a few g/l Sodium Sulfite in water, it becomes next to impossible to dissolve Metol. The biggest accomplishment of Kodak's D-76 was, that they managed to pack D-76 into a single powder bag, and prepare the powder in a way, such that the Metol fully goes into solution before the Sodium Sulfite is exposed to water. All the other D-76 powder kits require two bags - number one containing Metol and some stuff, number two containing the Sodium Sulfite and the whatever bag #1 did not provide.I think it was @Photo Engineer in this forum who said that Kodak make a blend of chemicals that go in a developer sachet and they cover the development agents used with sulfite. This should reduce oxidation of these agents drastically while the product stays on the shelf.
If you compare Haist's version with the original one, you can trade 5g HQ for about 0.5g extra Metol and still get the same activity. This tells me, that the HQ is not overly active at this pH. However, none of these proponents of D-76H ever showed developer capacity compared to regular D-76, owing largely to the fact, that many of these publications (including FDC and FDC2) vehemently oppose developer reuse. If only a small fraction of HQ is active at pH 8.5, then the inactive HQ may well replace active HQ used up during development, keeping the developer more stable over time or with reuse.Why have HQ at all in the formula if it is not "activated".
Rotary reportedly has top consistency, but IMO there are several factors:
> In summer (for BW) the rotary requires a modification in the Thermostat to cool the bath by allowing to source sub 20ºC watter (opening an electrovalve).
> Temperature control in trays is also perfect if we nail the darkroom air temp at 20ºC, or if we use a thermostatic bath.
> Agitation in trays can also be totally consistent if taking care.
> Trays are also daylight is we use a paper safe as the tray, or if we put it inside a paper safe.
> Total consistency in development (time/temp/agitation) is not that critical if anyway we later have to adjust paper grade for each shot. Personally I try to be as consistent as possible, but IMO 20 seconds more or less of effective development are mostly irrelevant.
Yes... in the highlights !!!
But this is allowed by tray/tank development. With a reduced agitation pattern (say 10s each 3 or 4 min) and extending a bit development (30-50%) we allow a regular development for mids/shadows but we limit developement in the highlights, conserving better highlight texture.
Contrary to what is often said, compensation in the highlights does not mainly come from developer exhaustion, but from not removing Bromide by-product from the emulsion as long we not agitate. In the highlights more silver bromide reacts to deliver more free bromide, and bromide is exactly a restrainer that slows development, as equilibrium is displaced.
In fact by controlling agitation we restrain more or less development in the highlights by allowing to accumulate temporary Bromide locally in the highlights, while rotary removes bromide inmediately.
Of course this is irrelevant in many scenes in what "rotary or not rotary" has little effect, but IMO there are scenes where it can be important to not blow extreme highlights, or to make them printable in an easier way. In particular I find that controlling agitation is a very good resource for night photography, as shadows have higher LIRF then we easily blow highlights if exposing to get the shadows, it's no secret that stand (or semi) processing can be powerful in that situation.
There may be detectable differences between classic D-76 and Kodak's single bag version, but neither version will make or break a negative.
My conclusion is, that it's best not to get hung up over some small differences in developers. You won't fall of a cliff, if you mix your D-76 with 80 or 120 g/l Sulfite, or if you add 4 g/l instead of 2g/l Borax. There may be detectable differences between classic D-76 and Kodak's single bag version, but neither version will make or break a negative.
In a double blind situation, I don't think you'd be able to tell the difference between a continuously agitated negative and one with extended agitation cycles, if they were developed to matched contrasts.
It is quite amazing, how far a histogram has to be off before the effect becomes visible. Your statement tells more about the sensitivity of measurement setups than the significance of subtle differences in the image. There are endless threads about modified C-41 processes, which give terrible control strips, but decent looking images.To realize in which amount this happens what I did is taking scans of regular vs stand, with matching contrast, then with Ps I took crops of textures and compared histograms, the difference is more than remarkable, it's huge. Many times the tonal distribution of the texture was doubled in width, the histogram shows it quantitatively.
It is quite amazing, how far a histogram has to be off before the effect becomes visible. Your statement tells more about the sensitivity of measurement setups than the significance of subtle differences in the image. There are endless threads about modified C-41 processes, which give terrible control strips, but decent looking images.
It is quite amazing, how far a histogram has to be off before the effect becomes visible. Your statement tells more about the sensitivity of measurement setups than the significance of subtle differences in the image. There are endless threads about modified C-41 processes, which give terrible control strips, but decent looking images.
An strong compensation requires always low agitation, but agitation alone may not be enough for an strong compensation, this is also true. Rotary does not alow compensation, tanks and trays allow it in the degree you want with right techniques.
Compensation has many factors: kind of developer, dilution, agitation and additional techniques. In the additional techniques you may use intermitent water bath, for example.
It is true that reduced agitation may not have a great compensation effect for many scenes, or better said simple compensation from agitation is seen only in areas of very high overexposure, but we may make very strong compensations for the highlights if you want and none of those can be made with rotary processing.
Regarding adjacency effects, we cannot overlook how textures greatly increase microcontrast in stand and semi-stand. To realize in which amount this happens what I did is taking scans of regular vs stand, with matching contrast, then with Ps I took crops of textures and compared histograms, the difference is more than remarkable, it's huge. Many times the tonal distribution of the texture was doubled in width, the histogram shows it quantitatively.
IMO it's not only what agitation control alone does, it's also what it allows to do with compatible techniques.
This seems like a lot of words that are very delicately trying to sidestep a lack of experience and properly rigorous testing.
There is likely some visible - and noticeable - difference between regular development with full strength developer and stand development in dilute developer.
But is the difference between Kodak's and Ilford's D-76 versions really noticeable?
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