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Richard K.
9-Apr-2011, 20:15
've had this for over a year. The A bottle is cinched in the middle indicating that no further air has entered the plastic bottle and oxidized the developer. But, when I pour the 1:1:100 mix into water, the water turns momentarily greenish then clear then starts getting red-muddy. Is this stuff still good? I threw it out because I wasn't sure, rinsed the tray and put in PMK to do a few negs. The spent PMK developer looked really greenish-muddy compared to the deep blood brown-red I usually get. I guess it reacted with the Pyrocat HD residue even though I rinsed the tray? Can one use a single tray for both processes with wash/rinse in between alternate uses or should one use dedicated trays? Thank you! :confused: :)

Jim Fitzgerald
9-Apr-2011, 20:26
Richard I have used my HD for a little over a years and it has worked well. I keep it in Brown Glass bottles out of the light. I'd use the one year as a standard. I mix it from scratch so it is less expensive that way. I'd use separate trays just to be sure.

Diane Maher
10-Apr-2011, 07:21
As you use Pyrocat HD, the mixture does turn to a dark color as it begins to oxidize. I use mine in a Jobo Expert tank when developing, so I don't know how fast it changes color.

Edit: I should say it is dark when it is spent/oxidized. Sorry!

Diane

Colin Graham
10-Apr-2011, 08:37
Plastic soda bottles are fairly air permeable, so I probably wouldn't trust the stock solution after a year. The Pyrocat-P working solution does turn wine colored even when fresh, but I've never seen the original Pyrocat-HD tint like that at any dilution, unless spent.

It sounds like you might be mixing A and B directly together, then pouring that into the water. I usually add the A component to the water, rinsing the grad thoroughly before adding the B part.

Richard K.
10-Apr-2011, 08:42
Has the water turned momentarily greenish for you when you first pour the developer in?

Richard K.
10-Apr-2011, 08:44
Plastic soda bottles are fairly air permeable, so I probably wouldn't trust the stock solution after a year. The Pyrocat-P working solution does turn wine colored even when fresh, but I've never seen the original Pyrocat-HD tint like that at any dilution, unless spent.

I guess I better mix fresh!


It sounds like you might be mixing A and B directly together, then pouring that into the water.

Yes, is that bad?

Colin Graham
10-Apr-2011, 08:46
Has the water turned momentarily greenish for you when you first pour the developer in?

I've never noticed that, no. I do use a light gray tray for development though, not sure if that would mask a greenish tint or not.




Yes, is that bad?

That seems like it would likely accelerate the oxidation/exhaustion, not sure if it's an absolute no-no, but I haven't risked it.

Gem Singer
10-Apr-2011, 09:02
Sounds like you are contaminating the A and B solutions.

Do not mix parts A and B directly together in the same measuring device.

For example, add 10ml part A to 500ml water in a measuring device. Add 10ml part B to 500ml water in a separate measuring device. Pour the two 500ml solutions into the developing tank to make 1,020ml of working solution.


At that point, a light color change to olive green is normal.

Richard K.
10-Apr-2011, 10:44
Thanks Gem...

lbenac
10-Apr-2011, 11:21
Sounds like you are contaminating the A and B solutions.
Do not mix parts A and B directly together in the same measuring device.
For example, add 10ml part A to 500ml water in a measuring device. Add 10ml part B to 500ml water in a separate measuring device. Pour the two 500ml solutions into the developing tank to make 1,020ml of working solution.
At that point, a light color change to olive green is normal.


I did not know about that :eek:
How does the contamination of the concentrate takes place when pouring into the same device?
I can understand it for Divided Pyrocat where residue of A could be left to contaminate the working solution B but I cannot see how pouring out of a bottle would contaminate the concentrate in that bottle.
I am very interested as I have Pyrocat HD in glycol in two Brown bottles that I am hoping to keep good for a year or until finished. Shipping Pyrocat (or other chemicals) from the US to Canada is always a little bit expansive.

Thanks for the tip

Luc

mandoman7
10-Apr-2011, 11:24
Perhaps its too obvious, but films can have different colored backing such that the rinses will have different coloring than you might expect if you've changed films. Otherwise, I would say glass bottles are in order.

Gem Singer
10-Apr-2011, 11:54
Luc,

The measuring device should be clean and dry each time it's used. If not, it's possible for contamination to take place. Especially true if it's made of plastic.

It's easier and safer to use separate measuring devices for part A and part B than to clean and dry the same one over and over again.

Part A and part B should be mixed together after diluting with water. Mixing the two concentrates together before diluting leads to rapid oxidation.

I have found that Pyrocat-HD in glycol lasts a long time (more than a year) in the original brown plastic bottles from Photographer's Formulary if I'm careful not to contaminate part A and part B, and tighten the caps back on the bottles immediately after use.

lbenac
10-Apr-2011, 13:36
Thanks Gem.
Now I get it :) and of course I was doing it the wrong way. I will do it right from now on. I already have the measuring devices (plastic I am afraid) marked A and B for preparing diluted Pyrocat which BTW I was never able to success with :(

Cheers,

Luc



Luc,

The measuring device should be clean and dry each time it's used. If not, it's possible for contamination to take place. Especially true if it's made of plastic.

It's easier and safer to use separate measuring devices for part A and part B than to clean and dry the same one over and over again.

Part A and part B should be mixed together after diluting with water. Mixing the two concentrates together before diluting leads to rapid oxidation.

I have found that Pyrocat-HD in glycol lasts a long time (more than a year) in the original brown plastic bottles from Photographer's Formulary if I'm careful not to contaminate part A and part B, and tighten the caps back on the bottles immediately after use.

nolindan
10-Apr-2011, 13:52
Mixing the stock solutions won't cause oxidation - there just isn't enough oxygen present in the system.

Pyro won't act as much of a reducing agent in an acid environment - which is why solution A seems to last forever; I don't think one needs to be overly careful for storage. I use glass bottles on a general good practices philosophy, I don't think it is neccessary, though. FWIW PF supplies their stock solutions in bog-standard plastic bottles.

Pyro when it goes from an acid to a base solution does some funky color changes, going from clear to green and eventually settling down to a pale orange. That the concentrates form a murky red-ish mess isn't surprising. If the resulting developer is pale orange after dilution with water then things are probably OK. It's easy enough to test by dropping a bit of scrap film in and seeing if it turns dark in a few minutes.

Mixing the concentrates will result in a very alkaline solution. I don't know that this will or will not have any effect.

You can always take a test picture on a bit of film and drop it in a beaker of a few oz of developer and see if it develops properly.

Pyros of all types turn a dark color after they are done developing. Jobos are the worst, and even Rollo Pyro is a dark mess after a 5 minute spin in the tank.

I don't know how a measuring device can contaminate the stock solution unless it is a pipette or one is in the habit of over-pouring and then returning the excess to the stock bottle.

Richard K.
10-Apr-2011, 15:30
Thanks for your excellent answer, Nicholas. The colour change sequence is exactly as I observed so maybe my developer is OK. I will test it. :D