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Diluted D-76 & Imporved D-76 at dilution
"Lew" wrote in message ... 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. 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 |
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Diluted D-76 & Imporved D-76 at dilution
"Lew" wrote in message ... On Nov 13, 6:11 pm, "Richard Knoppow" wrote: "Lew" wrote in message ... 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. Thanks, Richard. This increased densities to those I am used to 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 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 |
#3
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The Borax in 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. |
#4
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Diluted D-76 & Imporved D-76 at dilution
"Keith Tapscott." wrote in message ... "Lew" wrote in message ...- 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.-The Borax in 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 Los Angeles, CA, USA |
#5
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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. |
#6
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Diluted D-76 & Imporved D-76 at dilution
"Keith Tapscott." wrote in message ... Richard Knoppow;848014 Wrote: _The_borax_is_not_a_buffering_agent,_it_is_an_alka li_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. 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 -- Richard Knoppow Los Angeles, CA, USA he borax in D-76 is indeed a pH 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 Los Angeles, CA, USA |
#7
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Quote:
Keith. Last edited by Keith Tapscott. : December 2nd 09 at 07:49 PM. |
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Diluted D-76 & Imporved D-76 at dilution
"Keith Tapscott." wrote in message ... Richard Knoppow;848165 Wrote: "Keith Tapscott." 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". I HAVE TO DISAGREE THAT BORAX IS A POOR BUFFERING AGENT 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". AFTER USING D-76 FOR MANY YEARS, I FOUND THAT I WASN`T 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 SEE ANY BENEFITS THAT D-76H MIGHT HAVE OVER D-23. 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". I HAVE SEEN THIS PUBLICATION MENTIONED MANY TIMES, AND 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. "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". I THINK THAT A PAPER WAS PUBLISHED BY R.W.HENN AND J.I. 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 Thanks for your correspondence 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 Los Angeles, CA, USA |
#9
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Quote:
D-23 replenished with DK-25R is all that is needed and does everything that D-76 does, but with better consistency. I found the development times with D-76d very long even when used at full-strength. Last edited by Keith Tapscott. : December 3rd 09 at 06:58 AM. |
#10
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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. |
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