Just bought large quantities of powder to make PyrocatHD

[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.blo...dian-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.