How long does pyrocat HD last?

CatLABS · Nov 23, 2013

I am sure this has been discussed many times:

How long does Pyrocat HD last after the bottles have been opened (but not mixed)?
Someone has suggested part B lasts longer then part A, anyone have actual numbers?

Tom Kershaw · Nov 23, 2013

No solid numbers, but I had major reliability problems with Pyrocat-HD when I used it in a Jobo ATL-2300 a few years ago, density and activity was uncertain. I think the concentrates probably last ok (e.g. 6 months) but proceed with caution. Generally I've come to the conclusion that a standard developer is fine in most applications, e.g. D-76 or XTOL.

Tom

CatLABS · Nov 23, 2013

I have had some issues with far less then 6 months, more like 6 weeks, and huge reliability issues.
The material is great but has been so unpredictable, is there any way to increase its reliability?

Tom Kershaw · Nov 23, 2013

Well six months months was a guess, I would need to check my notes. Some people have prepared Pyrocat-HD in glycol solutions but I find XTOL now works perfectly well and I've become somewhat suspicious of magic brew type developers. Do you want to use Pyrocat-HD for a particular reason?

Tom

Thomas Bertilsson · Nov 23, 2013

CatLABS said:
I have had some issues with far less then 6 months, more like 6 weeks, and huge reliability issues.
The material is great but has been so unpredictable, is there any way to increase its reliability?

Did you get any cross contamination between the two bottles of concentrate, perhaps?

The best thing you can do is probably to make smaller batches of it. Even if you make 1 liter batches, divide them up in smaller bottles of, say 250ml each. That way the concentrates are kept under ideal conditions until you use them.

You may also use glycol to mix the chemistry, which has a good effect on longevity.

I had Pyrocat-HD in glycol that lasted well over six months. Then I had a batch go bad on me within six months after that. Impossible to give hard numbers, I should say, but if you do the above and avoid contamination you should be OK for a long time.

Black Dog · Nov 23, 2013

IME PCAT lasts for at least a year in separate bottles-I have a cool darkroom too!

Gim · Nov 23, 2013

I mixed up 5 liters of pyrocat HD in glycol at the end of 2006. I'm still using it with no problems.

CatLABS · Nov 23, 2013

Agreed, "magical" mystery solutions never beat standardized materials, but Pyrocat HD gave some wonderful results, without having to complicate things too much.
I guess mixing in glycol (i thought it already was) can help, but not sure if thats the way to go now.

While D76 ALWAYS works to produce usable images, it sometimes looks, well, pretty bad. That is of course compared to orher more complex/expensive options.

Is glycol a liquid to be had from photographers formulary?

Ian Grant · Nov 23, 2013

It depends on the freshness and purity of the Metabisulphite, and also the quality of the storage bottles for Part A. I'm assuming not made up in a glycol.

The first 2 batches I made up it was weeks, that was mainly down to the plastic storage bottle which were low density. I realised the plastic bottles were an issue and quickly began using High Density bottles (Agfa & Ilford bottles) and that made a huge differance. I also noticed that when Pyrocat collapsed there was no SO2 smell.

Remember that Bisulphite is an inferior grade of Metabisulphite and is far less effective as a preservative. The longevity of Pyrocat depends on how long it takes for the |metbisulphite to decompose completely, after that the Pyrocatechin oxidises quickly With very fresh Metabisulphite 2½ years is the best I've had so far.

Ian

Klainmeister · Nov 23, 2013

I've gone 14 months before finally seeing a weaker image so I bought a new set.

CatLABS · Nov 23, 2013

the difference i saw was quite dramatic, from good density, under control, to almost nothing.

I can say for sure that these were kept in the original stock black containers, and were mixed with separate vessels. The only source of contamination i can think of is using the same syringe to extract correct amounts from each container. That might have been my own undoing.
Though i did throughly wash it between parts...

Loris Medici · Nov 23, 2013

Not exactly an answer to the original question, but I still use the same stok of Pyrocat-MC in glycol that I've mixed myself in mid-2007 w/o any adverse effects. The B solution is even older... (A solution contains very small amnt. of water, it was before the alternative hot / non-water mixing instructions were published.)

Regards,
Loris.

Regular Rod · Nov 23, 2013

OBSIDIAN AQUA seems to last very well, years rather than months...

A lot easier to make up and the results are simply excellent.

RR

erikg · Nov 23, 2013

I always use PyroCat mixed with glycol and have had it last over a year. I don't know how long it could go because I used it up. D-76 changes in activity over time and xtol goes dead with no color change. Really though if you're not using up your developer within 6 months you're not shooting enough.

CatLABS · Nov 23, 2013

I bought it and used it several times, and liked the results, but then had gone through 3 (or more) gallons of d76 (and many gallons of C41) before going back to the Pyrocat only to find it was no good no more.
It was the smallest they sell, it couldent have been much left in there, i was planning to get the larger option the next time.

So - where/how do i get and mix glycol?

Thomas Bertilsson · Nov 23, 2013

I honestly don't know what kind of glycol you should be using, even. You could always buy the kits from Photographer's Formulary, which they already sell mixed in glycol. Or if you want to do the mixing on your own, perhaps PM Gerald Koch or Ian Grant, or some other knowledgeable chemist on this web site.

Thomas Bertilsson · Nov 23, 2013

Here is a link to the Pyrocat-MC material safety data sheet. It looks like standard propylene glycol that they're using, which you should be able to purchase in auto supply stores. But I'm not sure whether some other grade than car grade glycol is needed or not.

http://stores.photoformulary.com/images/store_version1/01-5096 Pyrocat-MC Glycol MSDS.pdf

Ed Bray · Nov 24, 2013

I make up my own Pyrocat HD part A 1 litre at a time from the raw materials. I have never had it 'go bad'. I store it in either Brown (Chemical) or Green (ex beer bottles). The part B I make up fresh before use.

I have this year started using it as a divided developer 1:10 ratio for 6 minutes each part where I feel it really comes into its own with an absolutely amazing Dynamic Range (remember to add a few drops of wetting agent to part A to prevent streaking).

Gim · Nov 24, 2013

I mixed mine in Dec. 06 with chemicals from Artcraft Chemical and The Chemistry Store. I used the Propylene Glycol from the Chemistry Store as it may be more pure than PG sold as antifreeze in the auto stores. The chemistry story, I believe, mainly sells to soap (and stuff) makers but they do carry some chemicals that we can use. I purchased Pot Carbonate & Sodium Sulfite there I believe.

The solution A is stored in 1L clear vodka bottles, kept in the dark in a cardboard box in the darkroom. Then broke down into 8oz or 4 oz brown bottles that just sit on the shelf for normal use. Solution B is made up about a liter at a time as needed and kept in clear bottles with no special care.

This was the first time I ever mixed any chemicals from scratch and it seems to have worked. Still using it from the 2006 batch.

Jim

How long does pyrocat HD last?

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