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Dk-76.
I saw a formula for a developer called DK-76 which is the basic D-76/ID-11 formula, except that the Borax is replaced with an equal weight of Sodium Metaborate. Is this an official `Kodak` formula?
http://www.digitaltruth.com/techdata/dk76.php Last edited by Keith Tapscott. : July 17th 08 at 12:00 PM. |
#2
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Dk-76.
Keith Tapscott. wrote:
I saw a formula for a developer called DK-76 which is the basic D-76/ID-11 formula, except that the Borax is replaced with an equal weight of Sodium Metaborate. Is this an official `Kodak` formula? http://www.digitaltruth.com/techdata/dk76.php Yes. At one time it was believed to give better shadow detail. I do not know if that was true or not. D-76d is yet another similar formula, but its buffering is better. Its main advantage is that it does not gain strength with exposure to air (as in a partly filled bottle). It is the same as D-76, but instead of 2 gm/l of borax, it uses 8 gm/l of borax and 8 gm/l of boric acid. Many believe that is what you get if you buy commercial D-76. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 09:15:01 up 21 days, 18:35, 4 users, load average: 4.27, 4.31, 4.18 |
#3
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Dk-76.
"Keith Tapscott." wrote in message ... I saw a formula for a developer called DK-76 which is the basic D-76/ID-11 formula, except that the Borax is replaced with an equal weight of Sodium Metaborate. Is this an official `Kodak` formula? http://www.digitaltruth.com/techdata/dk76.php -- Keith Tapscott. It is although it was first published as Kodalk D-76 without the DK prefix. At the time it was thought that the metaboate would be able to buffer the pH of the developer but it was not effective so the buffered version D-76d, announced in 1929 remains the preferred version. DK-76 was formulated at the time Kodalk was made available by Kodak who published several developer and fixer formulas using it at the time. Kodak did not invent metaborate but did patent an economical method of producing it. The buffering is made necessary by a slow increase in pH in the original D-76 which affects its activity enough to cause problems in predicting results. This effect is caused by a slow reaction between the hydroquinone and the sodium sulfite which results in a small amount of sodium hydroxide. This effect was discovered shortly after the D-76 formula was first published (1927) and a research project at Kodak Labs resulted in the buffered version D-76. The researchers did not discover the cause of the pH increase, only that it did increase. The discovery of the hydroquinone/sulfite reaction was not made until the 1950s. For reference here are the two formulas: D-76 (original) Water (at 125F) 750.0 ml Metol 2.0 grams Sodium sulfite, desiccated 100.0 grams Hydroquinone 5.0 grams Borax, granulated 2.0 grams Water to make 1.0 liter The buffered version is: D76d Water (at 125F) 750.0 ml Metol 2.0 grams Sodium sulfite, desiccated 100.0 grams Hydroquinone 5.0 grams Borax, granulated 8.0 grams Boric acid, crystaline 8.0 grams Water to make 1.0 liter The above has the same activity as the original formula when its freshly mixed and retains that activity in storage. The activity can be varied over a wide range by changing the ratio of borax to boric acid. The Kodalk version is the same as the original version but uses 2.0 grams of Kodalk (sodium metaborate, octahydrate) in place of the borax. Current packaged D-76 is the buffered version. Virtually every film maker has published some version of D-76, they are all pretty similar in practical results. Kodak seems to have been the only one to recognize the necessity for buffering. -- --- Richard Knoppow Los Angeles, CA, USA |
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Thanks Jean-David and Richard for replying. I had not seen the DK-76 formula in any of my own Kodak publications and wasn`t sure if it was a genuine Kodak formula, thanks for clarifying.
I suspect that both Ilford as well as Kodak may well have made some subtle modifications to the basic formula over the years, I also suspect that the current Ilford ID-11R replenisher is close to the "modified" replenisher on page 17 of Kodak publication `03`. I have seen some excellent prints from a former commercial photographer who uses replenished ID-11 for processing B&W sheet-films. See page 7 of the ID-11 technical information "Replenishment".. http://www.ilfordphoto.com/Webfiles/...1159472874.pdf Quote:
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