Diluted D-76 & Imporved D-76 at dilution
Lew
would be less active at 1:3 dilution than standard, out of the box
D-76? Although my home made D-76 compares favorably with store bought
D-76, results at 1:3 seem underdeveloped.
Richard Knoppow
"Lew" <lew...@gmail.com> wrote in message
news:68d884b2-fd5c-4625...@u7g2000yqm.googlegroups.com...
It could be. The amount of metol in standard D-76 is
minimal. I would suggest increasing it to perhaps 5 grams
per liter.
Also, in general, the activity of the developer is
slightly lower than standard D-76. This is shown in the
graphs in the 1929 paper from Kodak Research Labs. Metol and
hydroquinone act to regenerate each other but in D-76 the pH
is too low to activate hydroquinone as an effective
developer. So, the developer works about the same without
the hydroquinone but has a shorter life and there may be
differences in such things as edge/border effects (less with
the hydroquinone present).
--
Richard Knoppow
Los Angeles, CA, USA
dick...@ix.netcom.com
Lew
> "Lew" <lew1...@gmail.com> wrote in message
>
> news:68d884b2-fd5c-4625...@u7g2000yqm.googlegroups.com...
>
> > Is it possible that my home brewed, 'improved,' no
> > hydroquinone D-76
> > would be less active at 1:3 dilution than standard, out of
> > the box
> > D-76? Although my home made D-76 compares favorably with
> > store bought
> > D-76, results at 1:3 seem underdeveloped.
>
> It could be. The amount of metol in standard D-76 is
> minimal. I would suggest increasing it to perhaps 5 grams
> per liter.
seeing. I also took advantage of a Gainer post on Apug in which he
states that there's little or no harm in increasing the borax in the
formula as well.
> Also, in general, the activity of the developer is
> slightly lower than standard D-76. This is shown in the
> graphs in the 1929 paper from Kodak Research Labs. Metol and
> hydroquinone act to regenerate each other but in D-76 the pH
> is too low to activate hydroquinone as an effective
> developer. So, the developer works about the same without
> the hydroquinone but has a shorter life and there may be
> differences in such things as edge/border effects (less with
> the hydroquinone present).
>
> --
> Richard Knoppow
> Los Angeles, CA, USA
Richard Knoppow
I have to find the citation for the Kodak research
paper. Among other things Kodak suggested increasing the
amount of borax up to perhaps 10 grams per liter as a way of
regulating gamma. This was left out of most of the
instructions for D-76. However, increasing the borax may
result in somewhat increased grain.
D-76 was originally published in 1927 in a data booklet
for a than new motion picture negative duplicating film. I
have never been able to find a copy. It was quickly adopted
for general purpose negative development. Before long it was
discovered that the activity was not constant but increased
over time. Kodak researched this problem and traced it to a
slow increase in pH. While they did not discover the
chemical basis of this for some thirty or more years they
did come up with a cure, namely to buffer the developer by
using a combination of borax and boric acid. This also
provided a way to vary the pH and thus the activity of the
developer so that contrast could be controlled without
changing development time. Since motion picture development
was slowly changing to machine processing at the time this
was of importance. It was discovered in the late 1950s (I
think) that the increase in pH was due to a slow reaction
between hydroquinone and sulfite which produced a small
amount of sodium hydroxide. This probably happens in all M-H
developers but is masked in those with carbonate or other
higher pH alkali accelerators.
Supposedly D-76 was the first developer to be
formulated with any understanding of the functions of metol
and hydroquinone in combination. Most other developers of
the time were the results of cut and try methods.
The introduction of photographic sound to motion
pictures required much tighter control of exposure and
processing. This is because the print contrast is fixed by
the requirements for the sound track. In photographic sound
tracks certain distortions occuring in the negative are
cancelled in printing but only when the negative and
positive are matched. This meant that the print development
could not be varied in order to compensate for variations in
the picture negative as commonly done in the silent picture
era. As a result the control of exposure and development of
the picture negative had also to be controlled pretty
accurately.
In the silent era most film, both negatives and
postives, were developed by semi-hand methods usually using
"rack and tank" type machines. Once sound was introduced
more automated developing machines began to be used. This is
also the period when research into replenishing processing
solutions began.
Movies have a lot to answer for:-)
--
--
Richard Knoppow
Los Angeles, CA, USA
Richard Knoppow
"Keith Tapscott." <Keith.Tapscott..554b5b8@photobanter.com>
wrote in message
news:Keith.Tapscott..554b5b8@photobanter.com...>> news:68d884b2-fd5c-4625...@u7g2000yqm.googlegroups.com...-
>> Is it possible that my home brewed, 'improved,' no
>> hydroquinone D-76
>> would be less active at 1:3 dilution than standard, out
>> of
>> the box
>> D-76? Although my home made D-76 compares favorably with
>> store bought
>> D-76 is there as a buffering agent. If you leave out the
> Hydroquinone, then you might as well leave out the Borax
> as well, as it
> is only mildly alkaline.
> The neatest answer is to use Metol and Sulphite alone, as
> in Hans
> Windisch`s Metol, Sulphite compensating formula and Kodak
> D-23.
>
>
>
>
> --
> Keith Tapscott.
The borax is not a buffering agent, it is an alkali for
the purpose of electrolyzing the developing agents and is
significantly higher in pH than sulfite alone. D-76d, a
Kodak formula is buffered by using a combination of borax
and boric acid to maintain a constant pH but it is the same
as the pH of freshly mixed regular D-76.
The pH of borax is not high enough to activate the
hydroquinone in D-76. Without the metol the solution will
barely develop at all. However, the hydroquinone still
interacts with the metol. The two act to mutually preserve
and regenerate each other so that D-76 has a larger capacity
than a similar developer without the hydroquinone.
Metol will develop quite nicely without the
hydroquinone, however, formulas with only metol in them
usually contain a considerably larger quantity of metol than
D-76 in order to have a reasonably high capacity. There were
numerous "fine grain" developers during the 1940s using
metol and carbonate. However, metol will develop even in a
slightly acid soluton so it can be used with sulfite along
as the alkali, as in D-23, or in sulfite buffered to neutral
with metabisulfite, as in D-25. both formulas have 7.5
grams/liter of metol in contrast to the 2 grams in D-76.
Kodak has never recommended D-76 at 1:3, however,
Ilford gives times for ID-11 for this dilution. They are
about right for D-76 also. At 1:3 either developer becomes a
high acutance develope with exagerated edge/border effects
and some compensation (shouldering off at high densities).
I've used it but don't much like the way it looks.
Low contrast is usually from insufficient development
time. At 1:3 D-76 will require at least double the time
given for it full strength and maybe more.
Kodak D-23 gives approximately the same grain and speed
as D-76 but with somewhat longer development times. It is
about the simplest developer formula possible:
Kodak D-23
Water (at about 125F or 52C) 750.0 ml
Metol 7.5 grams
Sodium sulfite, desiccated 100.0 grams
Water to make 1.0 liter
Here is Windisch's version as a compensating developer,
probably the one you mean:
Water 1.0 liter
Sodium sulfite 100.0 grams
Metol 2.5 grams
Windisch proposed several developers. One well known one
uses orthophenylenediamine as a silver solvent.
Orthophenylenediamine is related to paraphenylenediamine, a
popular extra-fine-grain developer popular in the 1930s and
1940s but it has no developing activity.
Paraphenylenediamine was thought to produce extra fine grain
due to its considerable halide solvent properties. It did
this at a very considerable loss of speed and a need for
very long development times to achieve any degree of
contrast. It was usually used on combination with Glycin.
Windisch's idea was to combine the inactive form of the
developer with metol to obtain a very fine grain developer
which still delivered reasonable film speed. The formula for
this follows:
Windisch fine grain developer
Water (boiled) 600.0 ml
Sodium sulfite 55.0 grams
Orthophenylenediamine 7.0 grams
Metol 7.0 grams
Potassium metabisulfite 6,0 grams
Water to make 1.0 ml
Dissolve all the chemicals except the sulfite after the
water has cooled to lukewarm. When fully dissolved add the
sulfite and bisulfite.
Speed loss is about one stop.
The form of the sulfite is not specified but is probably
desiccated.
I have no idea if this is a practical formula.
A compensating developer attributed to Windisch follows:
Solution A
Water 100.0 ml
Pyrocatechin 8.0 grams
Sodium sulfite 1.25 grams
Soluton B
10 per. cent. solution of sodium hydroxide.
For normal use take 12 parts of A and 7 parts of B to 500
parts of water. He gives some other variations.
D-76 and D-23 do not need anti-foggants as would a
developer with carbonate. However, fresh D-76 (and probably
D-23) will deliver very slightly higher film speed if about
0.25 grams/liter of potassium bromide is added to the stock
solution. This suppresses a slight tendency to fog
characteristic of D-76 type developers. Where the developer
is re-used or used in a replenished system the bromide from
the film will accomplish the same thing.
For reference and comparison here is a typical fine
grain carbonate type developer of the same period:
Agfa-12 Fine Grain Tank Developer
Water (at 125F or 52C) 750.0 ml
Metol 8.0 grams
Sodium sulfite, desiccated 125.0 grams
Sodium carbonate, monohydrated 5.75 grams
Potassium bromide 2.5 grams
Water to make 1.0 liter
Richard Knoppow
"Keith Tapscott." <Keith.Tapscott..5560738@photobanter.com>
wrote in message
news:Keith.Tapscott..5560738@photobanter.com...
>
> Richard Knoppow;848014 Wrote:
>>
>>
>> _The_borax_is_not_a_buffering_agent,_it_is_an_alkali_for_
>> the_purpose_of_electrolyzing_the_developing_agents_and_is_
>> significantly_higher_in_pH_than_sulfite_alone._
>>
>> The pH of borax is not high enough to activate the
>> hydroquinone in D-76.
>>
>> as D-76 but with somewhat longer development times. It is
>> about the simplest developer formula possible:
>>
>> Kodak D-23
>> Water (at about 125F or 52C) 750.0 ml
>> Metol 7.5 grams
>> Sodium sulfite, desiccated 100.0 grams
>> Water to make 1.0 liter
>>
>> Here is Windisch's version as a compensating developer,
>> probably the one you mean:
>>
>> Water 1.0 liter
>> Sodium sulfite 100.0 grams
>> Metol 2.5 grams
>> Richard Knoppow
>> Los Angeles, CA, USA
>> buffer.
>
> http://www.borax.com/detergents/pheffect.html
>
> I have never really seen the point of the so called D-76H
> formula which
> isn`t an actual Kodak formula by the way, but is
> acknowledged as a
> suggested formula by Grant Haist, a former Kodak
> photo-chemist (hence
> the `H`).
> There is in fact an official Kodak formula called D-76h
> which is a
> buffered-borax MQ developer, just to add confusion. :)
>
> From MODERN PHOTOGRAPHIC PROCESSING (Volume 1) by Grant
> Haist on page
> 246.
>
> "THE SULFITE ALKALI`S. "Sodium sulfite is a weakly
> alkaline salt that
> is capable of acting as the sole alkali for developing
> agents of the
> amino groups, as for example, Metol or Amidol. Sodium
> sulfite is an
> alkali because it hydrolyzes in solution to produce sodium
> hydroxide"
> (caustic soda).
>
> The borax in D-76 is there to prevent or at least minimise
> a rise in pH
> due to the complexes formed by the sulphite to produce
> hydroxide which
> can activate the hydroquinone. If the hydroquinone is left
> out, then
> you don`t need the borax.
>
> As you have said, Metol-sulphite developers are as simple
> as it gets,
> so there is no need to add borax to obtain a very
> effective fine-grain
> developer.
>
> The formula I have seen for Windisch Metol-Sulphite
> developer is 2.5
> grams of Metol and 50 grams of sodium sulphite,
> (crystalline) in a
> litre of water.
>
> The point I am trying to make is if a D-76 type of
> developer is
> required, then keep the Hydroquinone in the formula and
> add a borate to
> stabilise the pH, other wise make a D-23 type instead.
> Sulphite is the
> only alkali required for the D-23 type of developer, there
> is no need
> at all to add borax or Kodalk.
>
>
>
>
> --
> Keith Tapscott.
I don't know where my copy of Haist is. The pH of D-76
is considerably higher than that of D-23 due to the borax.
Borax has some buffer action but is not a good buffer. The
reaction of hydroquinone with sulfite was not known when
D-76 was formulated nor was it discovered for about three
decades after. The rise in pH was observed and a buffer of
borax and boric acid was substituted for the borax only in
the D-76d formula described in Capstaff's 1929 paper.
If the hydroquinone isx not present there is probably no
rise in pH. If the borax is left out the effect will still
take place, as you state, but the activity of the developer
will be less. I think the target pH of D-76 is about 8.7, I
can't remember what it is for D-23. In any case, if the
hydroquinone is left out of D-76 there is little difference
in activity as pointed out in the 1929 paper which explored
something like 30 variations of the formula. The one thing
that they did not try was a metol-sulfite developer. I think
perhaps the films of the time would have required too long a
development time with it or, perhaps, they just didn't think
of it.
The paper was published in the _Transactions of the
Society of Motion Picture Engineers_ the quarterly
predecessor of the Journal. They are hard to find. I have a
copy because a friend with access to the MIT library Xeroxed
it for me. I will find the citation for you because it is a
very interesting paper. I don't think many other developers
were ever analysed as thoroughly as D-76.
There was another variation of D-76 which was published
sometime about the mid 1930 at the time Kodak was pushing
Kodalk (sodium metaborate) as an alkali for all developers.
This one uses Kodalk instead of borax. Supposedly it Kodalk
had better buffering qualities than borax but it turned out
not to so the formula was never used much. It is identical
to the original D-76 but has 2 grams per liter of Kodalk
instead of borax. I think its possible that Packaged D-76 at
one time contained metaborate but the current stuff is a
variation of the buffered formula.
D-25, pubished about the same time as D-23 (early
1940s) is D-23 buffered to neutral pH with metabisulfite.
The lower activity makes it a very fine grain developer but
I think it had problems with dichroic fog with some films.
The old DK-20 formula, which contained sodium thiocyanate as
a silver halide solvent had serious problems with post-WW-2
emulsions and was discontinued as a packaged product. It is
an interesting formula but no longer practical. D-25 is just
as fine grain and works for more films. Microdol-X has a
proprietary formula although there are similar formulas in
some Kodak patents. It uses sodium chloride (common salt) as
the fine grain agent. I think Haist talks about this a
little but doesn't really give a full explanation of how it
works. I think he may have been constrained by being a
former Kodak employee not to disclose stuff Kodak considered
trade-secrets.
--
Richard Knoppow
"Keith Tapscott." <Keith.Tapscott..55c9ebb@photobanter.com>
wrote in message
news:Keith.Tapscott..55c9ebb@photobanter.com...
>
> Richard Knoppow;848165 Wrote:
>> "Keith Tapscott." Keith.Tapscott..5560738@photobanter.com
>> wrote in message
>>
>> Richard Knoppow;848014 Wrote:-
>>
>> The borax in D-76 is indeed a pH
>> buffer.-
>> http://www.borax.com/detergents/pheffect.html--
>> Keith Tapscott.-
>>
>>
>> "Borax has some buffer action but is not a good buffer".
>>
>> FOR REASONS I
>> HAVE ALREADY PROVIDED IN THE LINK. YOU SEEM TO BE
>> IGNORING THE
>> COMPLEXES FORMED WHEN SULPHITE AND BORAX ARE DISSOLVED IN
>> SOLUTION.
>> D-76 DOES ONLY CONTAIN 2 GRAMS PER LITRE, BUT EXTRA BORAX
>> AS IN SOME OF
>> THE D-76 DERIVATIVES SUCH AS ANSCO/AGFA 17, ADOX BORAX MQ
>> AND KODAK`S
>> OWN D-96 WILL PROVIDE GREATER BUFFERING CAPACITY.
>> BORAX RELEASES A WHOLE MYRIAD OF BORON IONS WHEN IT IS
>> DISSOLVED,
>> INCLUDING B2O3 (BORIC ANHYDRIDE). IT IS MUCH MORE THAN
>> JUST A MILD
>> ACCELERATOR.
>>
>> "The reaction of hydroquinone with sulfite was not known
>> when
>> D-76 was formulated nor was it discovered for about three
>> decades after.
>> The rise in pH was observed and a buffer of
>> borax and boric acid was substituted for the borax only
>> in
>> the D-76d formula described in Capstaff's 1929 paper".
>>
>> USING MUCH OF
>> THE U.S. GALLON SIZES QUICKLY ENOUGH AND THE 1 LITRE SIZE
>> WASN`T VERY
>> GOOD VALUE FOR MONEY, SO I DECIDED TO MAKE MY OWN FROM
>> RAW CHEMICALS.
>> THE ONE`S I TRIED WERE D-76 (BASIC FORMULA) AND D-76D TO
>> START WITH. I
>> FOUND THE STANDARD FORMULA TO MATCH KODAK`S OWN D-76 FOR
>> TIMES AND
>> CONTRAST, WHILE THE SAME TIMES FOR D-76D GAVE ME VERY
>> UNDER DEVELOPED
>> NEGATIVES.
>> I ALSO MADE MY OWN CUSTOM D-76 BASED ON THE XTOL PATENT
>> WHICH I
>> PUBLISHED ON APUG IN THE NON-STAINING DEVELOPERS SECTION
>> WHICH WORKED
>> WELL. I THINK THAT \"MODIFIED DK-76\" WOULD HAVE BEEN A
>> MORE
>> APPROPRIATE DESCRIPTION.
>> "I think the target pH of D-76 is about 8.7, I
>> can't remember what it is for D-23. In any case, if the
>> hydroquinone is left out of D-76 there is little
>> difference
>> in activity as pointed out in the 1929 paper which
>> explored
>> something like 30 variations of the formula. The one
>> thing
>> that they did not try was a metol-sulfite developer. I
>> think
>> perhaps the films of the time would have required too
>> long a
>> development time with it or, perhaps, they just didn't
>> think
>> of it".
>>
>> I DON`T
>> PERSONALLY USE D-23, BUT I HAVE SEEN RESULTS FROM A
>> PHOTOGRAPHER WHO
>> USES D-23 REPLENISHED WITH DK-25R AND THE RESULTS ARE
>> SURPRISINGLY VERY
>> GOOD.
>> I DIDN`T THINK I WOULD EVER LIKE D-23, BUT I AM NOW
>> SERIOUSLY
>> CONSIDERING USING IT THE SAME WAY, FULL-STRENGTH AND
>> REPLENISHED HAVING
>> SEEN THE RESULTS.
>> THIS FELLOWS DEVELOPMENT TIMES AVERAGE AROUND 6-8
>> MINUTES, DEPENDING ON
>> THE FILM USED.
>> "The paper was published in the _Transactions of the
>> Society of Motion Picture Engineers_ the quarterly
>> predecessor of the Journal. They are hard to find. I have
>> a
>> copy because a friend with access to the MIT library
>> Xeroxed
>> it for me. I will find the citation for you because it is
>> a
>> very interesting paper. I don't think many other
>> developers
>> were ever analysed as thoroughly as D-76".
>>
>> WOULD APPRECIATE
>> A SCANNED COPY (PDF) IF THAT`S OK WITH YOU RICHARD[/B].
>>
>> \"THERE WAS ANOTHER VARIATION OF D-76 WHICH WAS PUBLISHED
>> SOMETIME ABOUT THE MID 1930 AT THE TIME KODAK WAS PUSHING
>> KODALK (SODIUM METABORATE) AS AN ALKALI FOR ALL
>> DEVELOPERS.
>> THIS ONE USES KODALK INSTEAD OF BORAX. SUPPOSEDLY IT
>> KODALK
>> HAD BETTER BUFFERING QUALITIES THAN BORAX BUT IT TURNED
>> OUT
>> NOT TO SO THE FORMULA WAS NEVER USED MUCH. IT IS
>> IDENTICAL
>> TO THE ORIGINAL D-76 BUT HAS 2 GRAMS PER LITER OF KODALK
>> INSTEAD OF BORAX. I THINK ITS POSSIBLE THAT PACKAGED D-76
>> AT
>> ONE TIME CONTAINED METABORATE BUT THE CURRENT STUFF IS A
>> VARIATION OF THE BUFFERED FORMULA\".
>>
>> [B](SEE MY COMMENT ON D-76D ABOVE).
>> SOMEONE SUGGESTED TO ME, THAT DK-76 MIGHT HAVE BEEN
>> USEFUL FOR
>> PROVIDING QUICKER DEVELOPMENT TIMES THAN THE STANDARD
>> FORMULA, WHICH
>> MIGHT HAVE BEEN WELL OVER 10 MINUTES WITH THE FILMS BACK
>> THEN.
>> CRABTREE CALLED
>> \"ELON SULFITE AND ELON, SULFITE-BISULFITE DEVELOPERS\"
>> AROUND 1944.
>> NOW THAT KODAK HAVE DISCONTINUED MICRODOL-X AND THAT
>> PERCEPTOL IS ONLY
>> AVAILABLE IN 1 LITRE SIZE PACKAGES, IT MIGHT BE WORTH
>> EXPLORING THESE
>> TYPES OF DEVELOPERS FURTHER.
>>
>> --
>> --
>> Richard Knoppow
>> Los Angeles, CA, USA
>> Richard.
>
> Keith.
>
>
Despite what the article says the buffering action of
Borax alone is not sufficient to maintain the pH of D-76.
The pH rises slowly due to the reaction between the
hydroquinone and the sulfite. Also, the main purpose of
Borax in the formula was to raise the pH not to act as a
buffer. Why Capstaff chose Borax is unknown. D-76 was about
the first developer to use it rather than a carbonate. D-76
was intended to be a fine grain soft working (meaning fairly
slow) developer for dupicate negatives but was quickly
adopted for general negative work in the motion picture
industry.
Richard Knoppow
"Keith Tapscott." <Keith.Tapscott..55d9bde@photobanter.com>
wrote in message
news:Keith.Tapscott..55d9bde@photobanter.com...
>
> In the British Photographic Almanac 1957, the D-76d
> formula (also known
> as Ilford ID-166) was the developer used to compare some
> of the then,
> new PQ fine-grain developers designed by Kendall and
> Axford which led
> to the introduction of Ilford Microphen.
>
> The MQ buffered-borax developer lost activity and
> effective film speed
> quickly when KBr was was raised above 0.25 grams per litre
> of
> stock-solution. Developers such as Ilford ID-68 and
> Microphen had good
> stability and working capacity with negligible loss of
> film speed
> compared to the MQ developer with reuse and with minimal
> increase in
> graininess compared to D-76d.
>
> Unfortunately, Ilford discontinued Microphen replenisher a
> long time
> ago. Ilford DD designed for Dip & Dunk processors and it`s
> amateur
> variant DDX are buffered-borax developers which fully
> exploit film
> speed. Perhaps in the fullness of time, these developers
> will remain
> while Microphen might be discontinued.
> Xtol is an interesting alternative to D-76 and Microphen.
> It would be
> nice if Kodak designed a liquid concentrate similar to DDX
> based on
> their Xtol formula.
>
>
>
>
> --
> Keith Tapscott.
I have never heard of this before Kendall and Axford are
well recognized photo scientists. Do you have a citation to
this work? In the old D-76 paper it was found that about
0.25 gram of bromide suppressed the slight fog typical of
_fresh_ D-76 resulting in a slight increase in film speed.
As far as reliability and activity is concerned remember
that buffered D-76 used with replenishment was a standard
developer for motion picture negative development for many
years. It would not have been if not reliable.
Adding bromide does lose film speed but does not affect
devloper activity, they are different functions.
Microphen is essentially buffered D-76 with Phenidone
substituted for metol and adjustments made for the required
pH. It requires some bromide due to the propensity of
Phenidone to produce fog. However, benzotriazole is more
effective because the anti-fog property of bromide is not
very effective with Phenidone. Microphen is not quite the
same as the published formula, for one thing it has a
different pH.
D-23 will mostly duplicate the results of D-76 as far as
film speed and grain but is not as long lived and can not be
replenished as long as D-76. The mutually regenerative
effects of metol and hyroquinone in D-76 extend its useful
life considerably.
I don't understand why you found development times with
buffered D-76 so long. It has the same activity and pH as
fresh standard D-76. The comparisons were done long ago by
Crabreee, et.al. in their 1929 paper.
Richard Knoppow
"Keith Tapscott." <Keith.Tapscott..55eed60@photobanter.com>
wrote in message
news:Keith.Tapscott..55eed60@photobanter.com...
>
> Richard Knoppow;848532 Wrote:
>>
>>
>> I have never heard of this before, Kendall and Axford are
>> well recognized photo scientists.
>> (1) DO YOU HAVE A CITATION TO THIS WORK?
>> *(2) In the old D-76 paper it was found that about
>> 0.25 gram of bromide suppressed the slight fog typical of
>> _fresh_ D-76 resulting in a slight increase in film
>>
>> As far as reliability and activity is concerned remember
>> that buffered D-76 used with replenishment was a standard
>> developer for motion picture negative development for
>> many
>> years. It would not have been if not reliable.
>> Adding bromide does lose film speed but does not affect
>> devloper activity, they are different functions.
>>
>> Microphen is essentially buffered D-76 with Phenidone
>> substituted for metol and adjustments made for the
>> required
>> pH. It requires some bromide due to the propensity of
>> Phenidone to produce fog.
>>
>> EFFECTIVE BECAUSE THE ANTI-FOG PROPERTY OF BROMIDE IS NOT
>> VERY EFFECTIVE WITH PHENIDONE. MICROPHEN IS NOT QUITE THE
>> SAME AS THE PUBLISHED FORMULA, FOR ONE THING IT HAS A
>> DIFFERENT PH.
>> *(4) D-23 will mostly duplicate the results of D-76 as
>> film speed and grain but is not as long lived and can not
>> be
>> replenished as long as D-76. The mutually regenerative
>> effects of metol and hyroquinone in D-76 extend its
>> useful
>>
>> (5)I DON'T UNDERSTAND WHY YOU FOUND DEVELOPMENT TIMES
>> WITH
>> BUFFERED D-76 SO LONG. IT HAS THE SAME ACTIVITY AND PH AS
>> FRESH STANDARD D-76.
>> The comparisons were done long ago by
>> Crabreee, et.al. in their 1929 paper.
>>
>>
>> --
>> --
>> Richard Knoppow
>> Los Angeles, CA, USA
>> and post the citations here.
>
> (2) I believe that Kodak call D-76d with 0.25 gram of KBr,
> SD-21. D-76d
> is said to cause higher base-fog than standard D-76/ID-11.
>
> (3) I don`t think the benzotriazole is required in
> Microphen types, due
> to their low-moderate pH. BZT is often used in PQ
> enlarging-paper
> developers, along with KBr.
>
> (4) D-23 is a very effective developer, there is a
> photographer over on
> APUG who uses D-23 replenished and claims to keep it
> working over
> several months before discarding the old stuff. I have
> also seen some
> good enlargements made with D-23 processed negatives.
>
> (5) I don`t understand why the times for D-76d are longer
> either, but
> they are. The film I used was HP5 Plus in D-76d diluted
> 1+1 and the
> negatives were very flat. I gave the time I normally use
> with packaged
> D-76.
>
> However, the standard formula gave excellent negatives at
> the same
> dilution. If Kodak are using a different way of buffering
> than just
> borax or with borax+boric acid, then they must have found
> a way to make
> the times the same as the standard formula. That is not to
> say D-76d is
> a bad formula, as long as a suitable time can be found
> through
> experiment. I think it might be better to use D-76d only
> at
> full-strength. Even then, I suspect that the times will be
> closer to
> the basic formula when that is diluted 1+1.
>
> What ever is going on with Kodak`s packaged D-76, then it
> is matching
> the basic developer for times. D-76d is behaving very
> differently from
> my own trial with it. Any idea why?
>
> Richard, do you have any raw chemicals of your own to
> experiment with?
> I ask because it would be interesting to compare your
> findings with
> mine. The chemicals I have were bought from Rayco in the
> UK, although
> Silverprint in London are now the main suppliers now that
> Rayco has
> ceased trading.
>
> Also, is it OK to contact you by PM or the email you have
> with your
> signature?
>
> Keith.
>
>
>
>
> --
> Keith Tapscott.
The answer to the last question is yes, its OK but you
will get a challenge message from the spam blocker at
Earthlink/Netcom. I will unblock you.
I have a few chemicals but my source for many years,
Tri-S Sciences, closed a couple of years ago and I have not
found a replacement although I could get most of the stuff
from Photographer's Formulary. I do have the necessary
equipment to mix stuff, a couple of good scales and the
glassware.
It would be interesting to know the actual pH of mixed
developers. According to Ryuji Suzuki measuring pH of
photographic developers is not trivial partly because the
solutions tend to destroy some types of pH meters.
Packaged D-76 is not the same as the published formula.
For one thing it is modified so that the metol can be
included in the same package as the sulfite. I don't know
how Kodak does this. It also uses boric anhydride which I
believe becomes boric acid in solution.
Original D-76 also causes a slight fog when fresh. When
re-used enough bromide is leached from the film to suppress
this. The 1929 paper shows that a small amount of bromide,
0.5 gram per liter, suppresses this in the fresh developer.
The smaller amount in the Kodak special developer may be
closer to optimum. AGFA also added the bromide to Agfa-17,
their version of D-76 which also has closer to the optimum
amount of sulfite, 85 grams per liter. For reference here is
the formula:
Agfa-17
Water (at about 125F or 52C) 750.0 ml
Metol 1.5 grams
Sodium sulfite, desiccated 80.0 grams
Hydroquinone 3.0 grams
Borax, granular 3.0 grams
Potsasium bromide 0.5 grams
Water to make 1.0 liter
I also found that AGFA had a metaborate version of this
formula. Its identical to the above but has 2.0 grams per
liter of Sodium Metaborate instead of the 3.0 grams of
Borax. Kodak also published a Kodalk version of D-76 called
DK-76, again identical to the original formula but with 2
grams of Kodalk in place of the borax. At the time the
metaborate was supposed to be a better buffer than borax but
evidently it isn't.
I think you are right about the use of bromide rather
than benzotriazole in Microphen. Anti-fog chemicals are most
effective at different pH.