Stability of 510-PYRO?

[Tony-S]

I get the impression this stuff is like Rodinal. Stable for years in concentrated form?

 

[paul_c5x4]

Don't know about "stable for years" - The two batches I've mixed to date have both gone dark, almost coffee coloured in about six months. But then I seem to be getting through a 100ml batch in a little over six months. As soon as some more TEA arrives, I'm going to be mixing another batch.

 

[mikebarger]

dark color has no effect on performance of 510 pyro. It's just into mid-life when Rodinal is dead and gone.

should get them going eh?

Mike

 

[Tony-S]

OK, is Ilford's Rapid Fixer an alkaline fixer? Or should I make up my own? The TF-3 looks simple to make, but it seems to have a short life once made.

 

[michaelbsc]

dark color has no effect on performance of 510 pyro. It's just into mid-life when Rodinal is dead and gone.

should get them going eh?

Mike

Crimey!! Aren't there enough religious wars going on in the world now?

 

[Gerald C Koch]

From my experience TEA and glycol based developers keep best when they were not overly heated during mixing. What I do is add the ingredients to the solvent and then with stirring slowly warm the mixture until everything dissolves. For some formulations you may not even have to heat the mixtures if you are patient. It may take a few hours or a day or so for everything to go into solution. Just add everything to a glass bottle, cap and gently shake periodically.

The darkly colored solutions may still develop film but may not be as active as fresh developer. The dark color comes from oxidized (and inactive) oxidation products of the developing agents.

Of the common developing agents pyrogallol has poor resistence to oxidation. Probably amidol is the only one with less resistence to oxiidation. Also phenidone slowly degrades in alkaline solutions. A better choice for 510 Pyro would be Dimezone S which was developed for better stability.

While these developers have good keeping properties they are nowhere near as stable as Rodinal or HC-110. Unfortunately there is a manufacturer of a Rodinal formula that is shipped in plastic bottles that do not promote stability to oxidation. This product goes bad very quickly unless it is transfered to a glass bottle. Agfa when it changed from glass to plastic used a composite bottle which blocked oxygen rather well. Still these bottles were not as good as glass ones.

The purpose of developers is to develop film not to be in a competition as to which one keeps best. The ingredients for 510 Pyro are relatively cheap and it is easy to make a new batch when there are doubts.

 

[Gerald C Koch]

dark color has no effect on performance of 510 pyro. It's just into mid-life when Rodinal is dead and gone.

should get them going eh?

Mike

Perhaps the 510 pyro is having a midlife crisis.

 

[Relayer]

I have partially used bottles of 510-Pyro mixed 2 year ago. it's still working very well

 

[mikebarger]

HC110 also gets darker as it gets older, but process times do not change.

 

[Tony-S]

Hmm, that's interesting because I've seen TF-3 recommended as a fixer and its formulation is:

Ammonium thiosulfate (58-60%) 800ml
Sodium Sulfite (anhydrous) 60 g
Sodium Metaborate 5 g
Distilled water to make 1000 ml

60g/L seems like quite a bit, but maybe not?

 

[Gerald C Koch]

So if you're using a Pyro developer and want maximum imagewise stain, you don't want to use chemicals that contain significant amounts of sulfite after development. Use a fixer that doesn't contain sulfite, and don't use a hypo clearing agent in your washing process.

I don't know if this is correct. The stain caused by pyrogallol, catechol, and hydroqionone consists of oxidation products (polyphenols) of the developing agent. These are lumped together under the term humic acids. The stain is dark colored and insoluble in water. I doubt whether the stain once formed can be bleached by the bisulfite ion in the fixer. The stain that forms in developer trays is the same substance and it is very difficult to remove requiring a strong bichromate bleach.

Humic acids are not soluble in acid solutions but dissolve in strongly basic ones.

 

[Gerald C Koch]

I have degrees in chemistry which is why I questioned the exposure to sulfite after development. From a purely chemical perspective the stain once formed is insoluble and hard to remove. It will only dissolve in concentrated solutions of sodium or potassium hydroxide. I doubt that sulfite ion is a strong enough reducing agent to bleach the stain.

Unfortunately there seems to be little scientific study of staining developers. What I have found on the internet is mostly conjecture and personal bias. There is also a lot of bad information and even mysticism. One example, the need to place the negatives back into an alkaline solution after fixing.

 

[Tony-S]

What are some non-acidic commercial fixers?

 

[john_s]

If near neutral is good enough, Kodak Flexicolor fixer (made for some kind of colour processing but quite suitable for black and white film and paper) is often significantly cheaper than "black and white" fixers. Its pH is around 6.5, so not far from neutral.

I use it since the demise of Agfa FX-Universal which was sold as a fixer for colour and black and white. Its pH was around 7.5 (so it was truly alkaline, but not much).

 

[Kirk Keyes]

If near neutral is good enough, Kodak Flexicolor fixer (made for some kind of colour processing but quite suitable for black and white film and paper) is often significantly cheaper than "black and white" fixers. Its pH is around 6.5, so not far from neutral.

Ilford Hypam fixer has a pH of about 5.5 and it works just fine with pyro stain.

I actually once developed two sheets of 4x5 film in PMK (maybe it was the original Pyrocat) and put one into a water rinse instead of stop bath, and the other went into Kodak Indicator Stop Bath. They then were fixed together. The sheet through the water bath was about 0.01 density units higher than the one in the Indicator Stop Bath. I atribute the difference to just random error of the densitometer, or perhaps the water bathed film continued development for just a few second more than the stop bath film.

But I hope this shows that pH of the stop has little effect on the pyro stain.

I suspect that the pH of the fixer has little effect as well.

 

[Tony-S]

Hmm, so maybe my Ilford Rapid Fixer will work just fine? Does it get discarded after the fix, or poured back into the bottle?

Thanks for all the replies so far.