PMK Pyro exhaustion, user error, or...

[fotoobscura]

I found a few bottles of liquid pyro concentrate sitting around that are at least 5 years old. They've been sitting in the dark and it looks like maybe I mixed one batch.

Anyhow, I found a roll of tmax 100 to develop, read a few posts elsewhere about pyro lasting "forever" unmixed and so I followed the directions to a T and sadly the film came out very poor (streaked up and down the negative, almost patterned) and in general the negatives were thin and garbage. It almost looks as if the developer was not evenly developing...

I fixed extra long to remove anti-halation dye and stained post-fix.

So I suppose the question is- does tightly capped unmixed liquid pyro last 5 years in the dark or did I somehow do something wrong? I suppose the film could have been bad but I doubt it..

Thanks

 

[Ian Grant]

Only a few developers have a 5 year shelf life. I would expect a Pyro dev to possibly have collapsed over that period of time. Storage is critical I found that Pyrocat keeps very well in old Ilford developer bottles but very poorly in some small plastic bottles I had left over from work. So yes PMK might have a long shelf life correctly stored. Some plastics breathe allowing oxidation to take place in a sealed bottle, this happens very slowly but then over 5 years this will be significant. Glass bottles should be far better.

The film will not have been the problem, even if very old it would process OK, and even if not perfect you'd get an image.

Ian

 

[nze]

I have 10 year old pyro pmk solution which still work well.
the only problem I have with pryo is with the Metaborate solution which keeps far less. I had a problem one day after a 2 months of shooting I start to develop my film and they do not have the DRange I use to have. In fact I make a new batch of metaborate and it works great. Till then I use to weight and mix my metaborate just before development.

 

[PhotoJim]

My PMK lasted seven years with no noticeable change in activity.

How was your agitation? PMK is notorious for needing frequent and violent agitation. (I agitate violently by inversion once every 15 seconds.) If you tried using rotary processing this time and normally did inversion, PMK is very prone to aerial oxidation when used this way and needs EDTA added.

 

[Bob Carnie]

We have found that once you mix the A and B into water the shelf live is very limited.
We process immediately to avoid problems you describe.

 

[David A. Goldfarb]

The stock solutions last a very long time. The working solution must be used immediately. It is advisable to mix the B solution with the water, and keep the A solution in a separate graduate, and mix it right before you are ready to develop the film.

The initial immersion of the film is also important with any staining developer to avoid streaking or mottling. If your tank fills slowly, then take the top off and pour in the developer in the dark, or fill the tank and drop in the reels, replace the lid, and proceed with the lights on as you normally would.