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#1
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Fomadon-P = D-76d.
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#2
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Fomadon-P = D-76d.
On Wed, 29 Jul 2009 15:49:54 +0100, Keith Tapscott.
wrote: Has anyone tried this developer? http://tinyurl.com/kqegre I haven't tried their developer, but I shot a lot of Foma B&W film in the past, and the quality was quite acceptable, so I would expect the same from their other products. |
#3
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Fomadon-P = D-76d.
"Keith Tapscott." wrote in message ... Has anyone tried this developer? http://tinyurl.com/kqegre -- Keith Tapscott. I have not tried it. I did a little searching around. The box suggests its D-76d, which is the buffered form of D-76. Kodak's packaged D-76 is of this type. The buffered formula was devised in 1929, a couple of years after the release of the original D-76 formula, because it was found that the original slowly increased in activity causing a significant increase in the contrast obtained after a given developing time. Kodak labs found that the pH of the solution increased slowly with time and that using a borax-boric acid buffer system would control it. There is an MSDS for the Foma product at the Freestyle site but its wrong listing sodium thiosulfate (hypo) as one of the ingredients. Of course, they mean sodium sulfite. The only other ingredients listed are metol and hydroquinone so its incomplete in any case. Assuming they followed the published formula for D-76d it should be about equivalent. However, Kodak includes other stuff in their packaged chemistry. For instance, D-76 comes in a single bag where the Foma product comes in two parts. This is because the metol normally must be dissolved before the sulfite or it becomes very difficult to get into solution. However, Kodak does something or includes something so that everything can be mixed at once. Also, Kodak packaged developers generally contain a sequestering agent for magnesium and calcium salts in the water. Of course, there is a big difference in price between the two and the Foma developer is probably quite satisfactory. For those who are interested here are the formulas for the two variations of D-76. Note that virtually every manufacturer of film or photo chemicals had some variation. Kodak D-76 (original 1927 formula) Water (at about 125F or 52C) 750.0 ml Metol 2.0 grams Sodium Sulfite, desiccated 100.0 grams Hydroquinone 5.0 grams Borax, granular 2.0 grams Water to make 1.0 liter Dissolve chemicals in order given. Kodak D-76d (1929 buffered formula) Water (at about 125F or 52C) 750.0 ml Metol 2.0 grams Sodium Sulfite, desiccated 100.0 grams Hydroquinone 5.0 grams Borax, granular 8.0 grams Boric acid, crystalline 8.0 grams Water to make 1.0 liter Do not use powdered Boric acid, it dissolves only with difficulty. Mix chemicals in order given. The two formulas have about the same activity when freshly mixed but the buffered version is stable where the original is not. -- Richard Knoppow Los Angeles, CA, USA |
#4
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Quote:
original is not." I have been researching D-76 (ID-11) and it`s derivatives for quite a few years now, including mixing some of the formulas from scratch. I have to say that I disagree that D-76 and D-76d have the same activity and that the buffered-borax version needs significantly longer development times to match the film contrast of those films which were developed in the commercial formula. I also found that the standard formula seems to match the commercial D-76 developer for developing times, unlike D-76d. Ryuji Suzuki provided some useful data about D-76 and it`s variants on his website. The MSDS for D-76 list diboron trioxide/B2O3 (boric anhydride), but from correspondence with a former employee at Kodak, is that D-76 commercial is identical to the published product, although there is a special method for encapsulating the developing agents, so they are protected against the other constituents in the single-powder. There are patents for packaging single-powder developers which you may be of interest to you. It wasn`t until recently that I noticed the Foma Fomadon-P packaging that gave me a clue as to why the development times are radically different. Take a look at the MASSIVE DEVELOPMENT CHART on the Digital Truth website for Fomadon-P. |
#5
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Fomadon-P = D-76d.
"Keith Tapscott." wrote in message ... Richard Knoppow;822714 Wrote: "Keith Tapscott." wrote in message ...- Has anyone tried this developer? http://tinyurl.com/kqegre -- Keith Tapscott.- I have not tried it. I did a little searching around. The box suggests its D-76d, which is the buffered form of D-76. Kodak's packaged D-76 is of this type. The buffered formula was devised in 1929, a couple of years after the release of the original D-76 formula, because it was found that the original slowly increased in activity causing a significant increase in the contrast obtained after a given developing time. Kodak labs found that the pH of the solution increased slowly with time and that using a borax-boric acid buffer system would control it. There is an MSDS for the Foma product at the Freestyle site but its wrong listing sodium thiosulfate (hypo) as one of the ingredients. Of course, they mean sodium sulfite. The only other ingredients listed are metol and hydroquinone so its incomplete in any case. Kodak D-76 (original 1927 formula) Water (at about 125F or 52C) 750.0 ml Metol 2.0 grams Sodium Sulfite, desiccated 100.0 grams Hydroquinone 5.0 grams Borax, granular 2.0 grams Water to make 1.0 liter Dissolve chemicals in order given. Kodak D-76d (1929 buffered formula) Water (at about 125F or 52C) 750.0 ml Metol 2.0 grams Sodium Sulfite, desiccated 100.0 grams Hydroquinone 5.0 grams Borax, granular 8.0 grams Boric acid, crystalline 8.0 grams Water to make 1.0 liter Do not use powdered Boric acid, it dissolves only with difficulty. Mix chemicals in order given. The two formulas have about the same activity when freshly mixed but the buffered version is stable where the original is not. -- Richard Knoppow Los Angeles, CA, USA Richard, you say that: "The two formulas have about the same activity when freshly mixed but the buffered version is stable where the original is not." I have been researching D-76 (ID-11) and it`s derivatives for quite a few years now, including mixing some of the formulas from scratch. I have to say that I disagree that D-76 and D-76d have the same activity and that the buffered-borax version needs significantly longer development times to match the film contrast of those films which were developed in the commercial formula. I also found that the standard formula seems to match the commercial D-76 developer for developing times, unlike D-76d. Ryuji Suzuki provided some useful data about D-76 and it`s variants on his website. The MSDS for D-76 list diboron trioxide/B2O3 (boric anhydride), but from correspondence with a former employee at Kodak, is that D-76 commercial is identical to the published product, although there is a special method for encapsulating the developing agents, so they are protected against the other constituents in the single-powder. There are patents for packaging single-powder developers which you may be of interest to you. It wasn`t until recently that I noticed the Foma Fomadon-P packaging that gave me a clue as to why the development times are radically different. Take a look at the MASSIVE DEVELOPMENT CHART on the Digital Truth website for Fomadon-P. -- Keith Tapscott. Kodak published a long technical paper in 1929 (I'll get the citation if you want) detailing the research on D-76. D-76 was originally published in a brochure describing a new fine-grain film for duplicating motion picture negatives, I have never been able to obtain a copy. It was rapidly adopted as the standard motion picture negative developer for the industry. It was originally used in rack-and-tank developing machines. It was discovered that there were problems with obtaining consistent development time. This was eventually traced to a slow rise in pH. Kodak cured this by using the buffer but the real cause was not discovered for a couple of decades. It turns out that a slow reaction between the hydroquinone and the sulfite generates a small amount of sodium hydroxide, enough so that after a month of storage the developer will produce the same gamma as fresh developer in slightly more than half the time. With the buffer the development time remains constant. The paper shows that the activity of the two formulae is very similar when fresh. Note that the activity of the buffered solution can be varied over a quite wide range by adjustment of the buffer. The paper includes a chart showing the variation with the ratio of the two components. This was an advantage where it was difficult to adjust processing speed, hense time, in automatic or semi-automatic machines. There are alternate names for a lot of common chemicals plus they can become different when in solution than when dry. Its possible that the current packaged version of D-76 is not exactly identical with the published D-76d but it is the same stuff. I can't account for large variations in activity other than the effects of poor control in the experiments. BTW, if you read Ryuji's stuff you know that measuring pH of photographic solutions, particularly developers, is not trivial. I think Kodak's old research is still valid. I am aware of Ryuji's work on developers. He found, for instance, that the optimum amount of sulfite for a D-76 type developer is around 80 grams/liter. The difference between that and the 100 grams/liter in D-76 is not large but is measurable. Agfa, in their Agfa 17, uses 80 grams/liter plus a slightly different ratio of hydroquinone to metol. They also add 0.5 gram/liter of potassium bromide. Kodak found that a small amount of bromide added to the unused developer would actually increase effective film speed slightly by suppressing a small amount of fog characteristic of D-76. If the developer is re-used the bromide leached out of the emulsion has the same effect. In replenished systems adding some bromide at the start is similar to the "ripening" or starting solutions used in color developing machines. Kodak also found that the presense of hydroquinone had very little effect on development. The pH of D-76 is too low to activate hydroquinone so it acts as a regenerator for the metol extending the capacity of the developer. In fact, D-76 without the hydroquinone is an effective developer and its life can be extended by using more Metol, perhaps 5 grams/liter as in D-23. Before D-76 was devised the motion picture industry used a variety of developers including Pyro with development by inspection. One reason for the supplanting of this by a different developer was that with the coming of sound pictures the film used for picture negative changed from orthochromatic to panchromatic eliminating development by inspection plus, at least for sound on film, a much tighter control of gamma was necessary. This required controlled automatic machines for release printing which, in turn, required much tighter control of the negatives since the prints could not be individually taylored to the negatives without changing the sound characteristics. -- Richard Knoppow Los Angeles WB6KBL |
#6
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The increase in the activity of M.Q. developers is well known. As the hydroquinone oxidises, it actually converts in solution to produce hydroquinone monosulfonate (HQMS) which is a much weaker, slower acting and more stable constituent than hydroquinone (HQ). HQMS is used in colour developers and is very expensive to buy and it requires a lot more HQMS in the formula to equal HQ. I have seen 5 parts HQMS to 1 part HQ cited as a very rough guide for making developers. The downside is complexes formed with the sulphite which produces hydroxide and increases the activity of the developer. Thus the pH of an M.Q. developer can cycle down, then up and be variable making a difference of around +/- 10% difference in development time compared to fresh. This difference is usually with unused undiluted developer in partly fillled bottles. The common practise these days, is to dilute stock developers with water and use them as a one-shot solution where these variations often goes unnoticed. What I can say having mixed D-76 and D-76d from scratch is that the standard D-76 formula seems to kinetically match Kodak`s commercial developer where as the D-76d buffered-borax version does not. I have seen mentioned some Ilford patents where a developer which resembles D-76/ID-11 but has increased borax in the formula of either 3 or 4 grams per litre of stock which also provides greater buffering capacity. I am not entirely convinced of Kodak`s MSDS either due to complexes formed when borax goes into solution which can form a whole myriad of boron ions in the developer. As some of the photo-chemist have mentioned to me, MSDS`s are a good way of disguising what goes into solution for those with little experience in chemistry. KODAK D-76 MSDS. Weight % - Component - ( CAS Registry Number). Concentrate: 85-90 Sodium Sulphite (007757-83-7) 1-5 Hydroquinone (000123-31-9) 1-5 Sodium Tetraborate (001330-43-4) 1-5 Bis (4-hydroxy-N-methylanilinium) sulphate (000055-55-0) 1 Boric Anhydride (001303-86-2) 1 Pentasodium (carboxylatomethyl) iminobis (ethylenenitrilo) tetraacetate (000140-01-2) Weight of concentrate = approximately 110 grams/litre. (This it self rules out D-76d formula which is 123 grams per litre of stock, not to mention sequestering agents etc). From the book "Modern Photographic Processing" by Grant Haist, Volume 1: Borate Alkali's: "Borax,Na2B4O7.10H2O, is the common name for sodium tetraborate, an alkaline compound used in the preparation of low-contrast, fine-grain developers. Borax may be written (NaBO2)2.B2O3, which shows the boric anhydride that limits the alkalinity possible from borax. Borax acts as a buffer; that is, it maintains a reservoir of alkali but delivers only small quantities of hydroxyl ions at any one time. The alkalinity is maintained relatively unchanged until all of the borax has been neutralised." As I don`t process as much B&W films these days, I no longer buy D-76 in the U.S gallon size packages and the 1 litre sizes are not as good value for money. I now make my own to the standard formula as and when required and I have found it to be very reliable despite what the 1929 publication says. In fact, I actually prefer the scratch-mixed developer which I use diluted 1+1. Try it and you may be pleasantly surprised with the results. :-) Last edited by Keith Tapscott. : August 1st 09 at 07:40 PM. |
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