Pyrocat-HD logevity

[nworth]

I needed to develop some film tonight. I looked in the cupboard and found some Pyrocat-HD (the original formula, mixed from scratch). The almost half full bottles were dated 16 December 2013 - pretty old. I didn't really feel like mixing new developer. I checked the Pyrocat-HD solution A. It looked good. In fact, it looked like new. One roll I had to develop didn't have anything even remotely important on it, so I decided to give the old developer a try. It worked fine. I tried it on a more important roll. It worked fine. The stock solutions, prepared with water, are a year and four months old and are still good. This kind of longevity is very good for a film developer. I suspect the solutions will last several more months.

 

[mrred]

The first bottle I bought were the original non-glycol version. It lasted 6 months, after I mixed it (powder). I got to use about half of it. You did not mention which version you have.

I just made the MC version with glycerine and there were reports of 3 years and going strong. Considering I made a litre of this stuff, that's not such a long time.

 

[ritternathan]

Yes, as long as you mix it without water and with as little heat as possible, store it in glass with little to no air, and are meticulous about how you mix the working solution (I use one dedicated syringe marked A) so that the A solution is not contaminated, it should last several years. Even the Formulary's -HD version I had lasted 3 years and that had some water mixed into it.

 

[nworth]

To clarify, the Pyrocat-HD I have is the original formula, mixed with water, and stored in PET bottles.

 

[mrred]

You did very well then.

 

[Ian Grant]

4 years now made up with de-ionised water and stored in old Ilford 1 litre developer bottles. The secret is reasonably fresh Sodium Metabisulphite and the right bottles.

The 4 year old Pyrocat HD is as good as my 3 week old batch.

Ian

 

[Andrew O'Neill]

Mine was mixed up last August and it's still good. Mixed from scratch with distilled water, stored in a collapsible brown container, in a cool dark place.

 

[mrred]

So how do you tell if your "Sodium Metabisulphite" is fresh?

 

[Ian Grant]

So how do you tell if your "Sodium Metabisulphite" is fresh?

Fresh Metabisulphite has a very strong smell of Sulphur Dioxide it's this that prevents the Developing agents oxidising in Part A. It's used in some powder developers in the packaging of Part A for the same reason.

Ian

 

[Matus Kalisky]

My experience is that the Pyrotat-HD (in glycol) will hold very long. However I have kept the bottles half-empty at some point. The solution A became denser and stronger in yellow color with time and started to cause streaks (probably because it did not want to resolve in water when preparing working solution). But that happened after several years.

 

[john_s]

4 years now made up with de-ionised water and stored in old Ilford 1 litre developer bottles. The secret is reasonably fresh Sodium Metabisulphite and the right bottles.

The 4 year old Pyrocat HD is as good as my 3 week old batch.

Ian

I'm about to mix up some Pyrocat-HD. I'm happy with the freshness of my ingredients except the sodium metabisulphite, which is a nearly full plastic jar from a brewing supplies shop, about five years old. It looks ok, but that probably means nothing.

Ian, what happens to it as it ages? What does it become?

 

[Ian Grant]

John, you'll know from the acrid smell of SO2 if it's OK 5 years should be OK, mine's at least that old..

Metabisulphite loses the SO2 over time, first becoming Bisulphite which in turn decomposes (usually in solution) to Sulphite. It's the free SO2 that protects the Pyrocatechin from oxidation.

I'm using or rather just finishing a third batch of Pyrocat HD that's just over 3 years old, and that's in a partially full bottle with a decreasing volume, so I'm very confident on the shelf life in the correct type of bottle.

Ian

 

[john_s]

John, you'll know from the acrid smell of SO2 if it's OK 5 years should be OK, mine's at least that old..

Metabisulphite loses the SO2 over time, first becoming Bisulphite which in turn decomposes (usually in solution) to Sulphite. It's the free SO2 that protects the Pyrocatechin from oxidation.

I'm using or rather just finishing a third batch of Pyrocat HD that's just over 3 years old, and that's in a partially full bottle with a decreasing volume, so I'm very confident on the shelf life in the correct type of bottle.

Ian

Thank you Ian.