Just bought large quantities of powder to make PyrocatHD

[Steven Ruttenberg]

I should not run out for a long time!

Question? What is the difference/benefit of using glycol vs water? Is there really any difference in quality of development?

[Jim Noel]

Glycol has far better keeping qualities than water. The P-Cat HD i have mixed in glycol has lasted over 2 years w/o noticeable change in negative quality.

[Steve Sherman]

I mix PyroCat HD in ordinary water, 1000ml at a time, store in a brown jug. I date every chemical in my Darkroom and have not seen any issues with PyroCat kept for 5-6 months.

[mrred]

I should not run out for a long time!

Question? What is the difference/benefit of using glycol vs water? Is there really any difference in quality of development?When using water, there is much lower chance of contamination from freshly cleaned syringes and other utensils. If you make quantities that are more reasonable for your consumption, you need not worry of it lasting long enough.

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[Jim Fitzgerald]

I've mixed from powders from day one. I've always used water to mix mine. It has lasted over a year in brown liter bottles. I keep it in the dark. I do use a lot for ULF film so I use it up rather quickly if I'm developing a lot of film. So if you mix in water shoot more film!!

[Steven Ruttenberg]

Shooting more film is option! Its crazy how many negatives I have yet to scan, not to mention print in darkroom when I build it next year.

Sounds like a personal preference really.

[Steven Ruttenberg]

I mix PyroCat HD in ordinary water, 1000ml at a time, store in a brown jug. I date every chemical in my Darkroom and have not seen any issues with PyroCat kept for 5-6 months.

I have taken to dating everything and have a boatload of 500ml brown jugs and half as much 1000ml. Mine are glass from PF.

[Mark Sawyer]

Developers age primarily by oxidation. Developers exposed to the air oxidize pretty quick, as air gives up its oxygen easily. Developers not exposed to air but mixed in water age more slowly because the water gives up its oxygen more slowly. Developers mixed in glycol and not exposed to air age slowest because glycol's oxygen is very stable and ain't goin' nowhere. That's why decades-old HC110 in full bottles is still good; it's mixed in glycol.

Keeping developers refrigerated also helps, because cold slows all that stuff down.

[Steven Ruttenberg]

Didn't think of refridgerating the stuff. I csn do that.

[Mark Sawyer]

Didn't think of refridgerating the stuff. I csn do that.

The best method would be to keep the stuff in powder form and mix as needed, within a few weeks of using it.

[jp]

I mix it in glycol and last time I made 1L of mix, I put half in a 500ml bottle and rest in 100ml bottles. Then 90% of it is never exposed to air more than a few times since I use 10-25ml at a time. The part-B mix just lasts and needs no special storage.

[koraks]

I too use glycol and mix tiny batches of 50ml at a time because I always use only 1-5 ml, so even 50ml lasts me quite some time. When I used water, oxidation was noticeably faster; I never noted problems, but to be safe I use glycol anyway.

[esearing]

I remember reading somewhere that substituting Metol for the phenidone could improve shelf life. Pyrocat M formula doesn't need the Bromide. Glycol adds to the cost as well. And you may want to try Jay Defehr's Hypercat and/or Obsidian Aqua now that you have the basic ingredients.
I have had Glycol mix go bad when purchased pre-mixed due to age. With the water version, the only problem I had recently was due to not shaking the part A bottle well enough and/or maybe letting it get below 68 degrees while sitting. Fresh small batches avoids both problems.

Pyrocat M:
Stock A
Distilled Water at 120F 750 ml
Metol 2.5g
Sodium Metabisulfite 10g
Pyrocatechin 50g
Water to 1000ml

Hypercat and OA formulas:
http://hypercatacutancedeveloper.blogspot.com/2012/07/obsidian-aqua.html

[jp]

I've been making pyrocat hdc which has one less ingredient and is thus simpler to make. Function is identical best I can tell.

[Doug Herta]

The historical consensus appears to be there are no differences in development quality between distilled water and glycol when using PyrocatHD.

If the OP is mixing Pyrocat HD from component chemicals from Artcraft Chemicals or other suppliers, I don't see the economy of using glycol - you can mix a quantity in distilled water that works for you. I mix 500ml at a time with distilled water in lower shooting periods and keep in 250mm brown bottles. Date label and throw out the remainder of any non-full bottle after 6 months. Adjust if you are not going through the developer (Shoot more! Mix less!). During periods of higher output I mix 1000mm at a time and keep in 500mm bottles.

Refrigeration sounds like a possible idea - for SOME. I bought (now make) various tonics to add to sparkling water, gin, lime (you get the idea). Store bought tonics around here come in 500mm brown glass bottles. I would not want party-goers to be mixing Gin and Pyrocat instead of Gin and Tonics. The fridge has film but nothing that could be mistaken for a beverage!

[Steven Ruttenberg]

That would be bad! Also stocking up on filmnin the event manufacturers go stupid and stop everything.