2 pyrocat-hd questions

1)
I am checking and comparing prices between mixing my own Pyrocat-HD and just buying premixed but I only know of two chemical places, Photoformulary, and artcraft chemicals. Are there other places?

2)
Ball park # of 8x10 sheets that can be run through a 1 gallon deep tank. That is a lot of chemicals and I want to maximize output and minimize waste. I have 5 racks.

mark said:

1)
I am checking and comparing prices between mixing my own Pyrocat-HD and just buying premixed but I only know of two chemical places, Photoformulary, and artcraft chemicals. Are there other places?

2)
Ball park # of 8x10 sheets that can be run through a 1 gallon deep tank. That is a lot of chemicals and I want to maximize output and minimize waste. I have 5 racks.

Click to expand...

The most expensive component is the propylene glycol, and I've found it much less expensive on ebay than the photochemical suppliers. My rule of thumb is about 200 ml / 8x10, so 19-20 sheets in a gallon.

Thanks Barry.

Right now there is free shipping at the Formulary for orders over 65.00 (no affiliation). Now if you are mixing the -HD in glycol and need more than a liter, go to the Tractor Supply store--they sell one gallon 99% pure for around $22. I also get the powder Ascorbic Acid at Trader Joes (if you are mixing -HDC version).

You can use propylene glycol instead of ethylene. It is non-toxic and safe to keep around the house if you have children and pets. I buy mine from http://www.chemistrystore.com. Their prices are quite reasonable $6.62/qt, $19.88/gal. They also sell some other useful chemicals.

mark said:

1)
I am checking and comparing prices between mixing my own Pyrocat-HD and just buying premixed but I only know of two chemical places, Photoformulary, and artcraft chemicals. Are there other places?

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For certain common chemicals used in various formulations, such as potassium carbonate, sodium metabisulfite, etc. you can't beat The Chemistry Store. Bostick & Sullivan also sells chemicals as well as pre-mixed Pyrocat HD, which is excellent.

All this glycol talk has me scratching my head. I got the recipe off unblinking eye and there is no mention of glycol. Is that recipe out of date and there is a new bester recipe?

Dissolving Part A in propylene glycol slows down the oxidation process and greatly extends the shelf life.

From the Pyrocat-HD site:

Pyrocat-HD (For one liter of Stock Solutions A and B)

Tests show that the Pyrocat-A stock solution is stable in partially full bottles for up to a year. If shelf life of longer than one year is desired I recommend mixing Stock A in glycol. Stock Solution B has indefinite shelf life.

Part A
Distilled Water (50¡ C) 750 ml
Sodium Metabisulfite 10 g
Pyrocatechin 50 g
Phenidone 2.0 g
Potassium Bromide 1.0 g
Distilled Water to make 1000 ml

Part B
Distilled Water 750 ml
Potassium Carbonate 750 g
Distilled Water to make 1000ml

Mixing directions for one liter of Pyrocat-HD Stock A solution in propylene glycol:

Weigh out all of the chemicals for Stock A. 50.0g of pyrocatechin, 10.0g of sodium metabisulfite, 2.0g of Phenidone and 1.0g of potassium bromide.
Pre-heat 750ml of propylene glycol to about 150F in a water bath or hot plate stirrer.
Add the pyrocatechin to the warm glycol and stir until dissolved. Should take no more than about a minute.
Add the phenidone and stir. Should dissolve completely in about a minute.
Add the bromide and sodium metabisulfite to about 50-75ml of hot distilled water at about 120F. Stir until completely dissolved, and then add this solution to the propylene glycol solution.
Top off the solution with glycol to 1000ml.

Mixing Directions for Stock B:

Start with 700ml of distilled water.
Weigh out 750g of potassium carbonate and add the chemical very slowly to the water, with constant and rapid stirring. If you add the solution too fast, or don't stir enough, it will be impossible to dissolve all of it in the water. As you add the chemical an exothermic reaction takes place and the solution will warm up appreciably.
Add distilled water to 1000ml.

Pyrocat-HD Stock Solution A, when mixed in propylene glycol, has a shelf life of several years.

Even when mixing your working stock with glycol-based concentrate, Pyrocat HD is a one-shot developer. You won't be able to get four batches of 5 sheets out of that gallon of developer. Maybe not on the second batch, but somewhere after the first batch, your developer will collapse and you'll have very thin negatives. You're much better off tray processing single-shot, or rotary processing single-shot.

Can you please explain collapse. I've never heard that before when talking about any sort of developer.

mark said:

Can you please explain collapse. I've never heard that before when talking about any sort of developer.

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Meaning that it will fail. The primary developing agent will have oxidized to a sufficient degree that it will no longer develop your film to completion. You'll put in properly exposed negatives that would develop normally with fresh developer given N time, but get out negatives that look 4-5 stops underexposed with that same amount of time. In other words, catastrophic failure.

collaspe is when you you reuse your developer for more than the recommended sq. in or sq. cm for dev/film ratio. if you use it more you risk the developer not working correctly. I think you need 250ml for 80 sq. in. some people say less. once you use it for that amount. discard it. do not attempt to run another set of film thru. this action if taken, will cause the dev. to "collapse". in other words not work. I do not use the glycol version. I use distilled water to mix all my chem's in. Many people here on Apug like to use the glycol version because it last longer, therefor they do not need to soup as often. I develop 4 sheets of 4x5 in 1000ml of 1:1:100. my times are a little bit different but I have leaned to work with it. But it is fresh, and i do not re-use. I have always gotten great results with developer. I always recommend this developer for any film and any format.

I think what flying camera is trying to say is that pyrocat hd oxidizes rapidly when mixed into working solution. Time becomes a factor as well as square inches developed. If you mix it to working solution and let it sit there even if you don't process any film at all it will still die.

TheFlyingCamera said:

Meaning that it will fail. The primary developing agent will have oxidized to a sufficient degree that it will no longer develop your film to completion. You'll put in properly exposed negatives that would develop normally with fresh developer given N time, but get out negatives that look 4-5 stops underexposed with that same amount of time. In other words, catastrophic failure.

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Scott is 100% right here. I've tried squeezing extra mileage out of Pyrocat HD in 1 gallon and 3.5 gallon tanks, with poor to fair results at best. Bottom line is that trying to save a few extra pennies on developer is not worth ruining a $4+ sheet of film (not to mention other costs associated with obtaining the exposure on the film!). Buying the components and mixing at home is much more economical in the long run.

As you may have noticed, there are several kinds of Pyrocat-HD, most particularly those where Part A is mixed with water and those where it is mixed in glycol. I don't know of any sources other that those you mentioned, but some may be out there. Pyrocat-HD was originally designed to be used as a one-shot for use with rotary processors like the Jobo. The issue with these processors was mostly ensuring adequate coverage of the film in the tank. I remember it took about 330 ml to process 6 sheets of 4X5 in the 2509N tank. Pyrocat-HD worked well with the recommended solution amounts at the standard dilution (1+1+100 for the water based version). The original documentation recommended 300 ml per 8X10 sheet for a rotary processor, with the tank type unspecified. That works out to about 13 sheets per gallon. Pyrocat-HD was not designed for deep tank use; it is meant for one-shot use at high dilutions. I have not made any tests, but I would guess that the life of the diluted developer is fairly short, although it resists aerial oxidation in the rotary processor quite well.

I make up my stock Pyrocat HD with de-ionised water. In the right type of bottle, high density plastic or glass, it lasts for over 3 years without Glycol and works perfectly. There is one proviso the Sodium Metabisulphite must be reasonably fresh as this prevents oxidation during storage, once all the Metabisulphite has broken down the Pyrocatechin oxidises rapidly.

Normally I get through Pyrocat HD quite quckly so there's no benefit of using Glycol, I did however make up some double strength Part A in propylene glycol about 5 years ago, (double strength to cut the weight when flying), I have Pyrocat HD stock in Turkey as well as the UK.

I didn't plan to keep Pyrocat HD Part A (without Glycol) for over 3 years, circumstances meant it had little use but it has kept well in a partially full bottle which is quite surprising.

Ian