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Pyrocat HD lasts for ages....??

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JDP

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Back in April 2011 I made up a batch of Pyrocat HD stock solutions (part A and B), with filtered tap water. They were stored in reused 'Calpol' bottles (anyone in the UK with Children is likely to be familiar with these - brown glass bottles with good quality plastic caps). The bottles are stored in a dark, cool cupboard. I mostly use Microdol-X so this developer has been only slowley depleted. The bottles are now about half full, and I have always filled the air gap with an inert gas after use. Anyway, I mixed up the latest working solution this weekend gone, and developed another film. It came out great. The solutions are now three years old, and seem to have plenty of life left.

Anyone beat that?!
 

Gerald C Koch

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With pyro developers the trick is to keep the accelerator (alkali) separate from the developing agents this greatly reduces the rate of oxidation. This is a very old concept as evidenced by ABC Pyro formula which uses 3 components. For developers like Rodinal and HC-110, well known for their longevity, 3 years is not much. For many years I have been using a rodinal type developer made from metol and hydroquinone rather than p-aminophenol. After 8 years a sample in a PET bottle shows no signs of oxidation. It is the same pink color as when it was made. Developers based on glycol solutions are also long lived.
 

Ian Grant

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3 years - yes it's possible I have some (only using water) that old that's as good as the day I made it up, it's part used in a recycled Ilford HD plastic developer bottle. It'll last as long as the Metabisulphite is still OK and there's SO2 in Part A.

Longevity is dependent on the freshness of the Metabisulphite when you make up Part A and we do get particularly good Sodium & Potassium Metabisulphite here in the UK.

Ian
 
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JDP

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I was surprised at the longevity as most indications I came across indicated a shelf life of 12 months; but I guess they were a little on the conservative side.

I must use it more, as I like the way it retains highlight detail.
 

Gerald C Koch

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A developer called Kalogen was first marketed in 1917 by Paul L. Anderson. For years, photographers had favored a German developer called Rodinal. With the outbreak of World War I, Rodinal was no longer available. Anderson created Kalogen to remedy this situation. The formula appeared in his book "The Technique of Pictorial Photography", J. B. Lippincott, 1939.

Distilled water (50°C) .................. 750 ml
Metol ....................................... 13.5 g
Sodium sulfite (anhy) ................... 180 g
Hydroquinone ............................. 53.0 g
Sodium hydroxide ........................ 25.0 g *
Potassium bromide ....................... 5.0 g
Benzotriazole, 1% ........................ 80.0 ml
Distilled water to make ................. 1.0 l

* see instructions below.

Method of Preparation

Weight out the Metol and sulfite. Dissolve a pinch of the sulfite in the water before adding the Metol. Dissolve the other ingredients in the order given. A precipitate will form upon the addition of the hydroquinone which will dissolve upon the addition of the sodium hydroxide. Add the 25 g of sodium hydroxide . The precipitate will probably not completely dissolve. Keep adding small amounts of hydroxide with constant stirring until the precipitate just dissolves.

Transfer the solution to a 1 liter glass or PET bottle, stopper and allow it to stand for 2 to 3 days. A small amount of impurities will precipitate out and the solution will become lighter in color. Filter the solution and transfer it to several small (2 to 4 ounce) glass bottles and label. When prepared correctly the solution will be a clear pinkish tan color.

When stored in nearly full and tightly capped small bottles, the stock solution will keep for months at room temperature. Should any crystals form due to storage at low temperature, they may be redissolved by warming and shaking the bottle.

The concentrate is diluted 1+29 to 1+59 for films. For the latter dilution the average development time is 5 min @ 22C. Kalogen also makes an excellent paper developer when diluted 1+11 to 1+14 producing results similar to D-72. Develop 2 to 2-1/2 min @ 22C. The formula was published by Walter C Snyder, Dignan Newsletter, August 1973, pp 13-14.

Walter Snyder in the Dignan Newsletter article said that the original formula called for 9 grams of potassium bromide. He reduced the amount and added the benzotriazole. He made other changes to the original formula changing the Metol/hydroquinone ratio from 1:2 to 1:4. I have the feeling that he never adjusted the sodium hydroxide amount which may explain why there is an excess in his formula. I calculate 26 grams for 98% purity sodium hydroxide as enough to just dissolve the precipitate.
 
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Ross Chambers

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Pardon me, but I just had a crazy idea (I've been compiling food recipes on and off this week) I use an "app" called Yummy Soup but there's a few out there.

This formula would drop into a food recipe compilation neatly, and be accessible along with any others that you want to keep.

Just a thought, if you have a number of formulae for developers etc.

Yeah, I know it's April Fools' Day.
 
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