How does Pyrocat go bad?

When Pyrocat goes bad, how does it do it? Does it just stop working or does it lose potency?

I'm doing film tests in the new garage darkroom and I'm seeing some really odd behavior from FP4+ souped in Pyrocat 1:1:100. I just finished the PSP calibration step that Phil recommends using FP4+ in DD-X 1+6 and it landed spot on 2.4, so I'm pretty sure I've got my exposure down right for the tests and I haven't touched the enlarger since calibration. The odd behavior is that the negs developed in Pyrocat look way, way under exposed. Here's an example from the 16 minute dev slice (all readings using white light).

Step DD-X Pyrocat
0.03 2.23 1.37
0.21 2.08 1.26
0.36 1.96 1.18
0.51 1.83 1.10
0.67 1.71 1.01
0.81 1.60 0.93
0.95 1.48 0.84
1.10 1.35 0.74
1.25 1.21 0.62
1.40 1.05 0.47
1.56 0.89 0.30
1.69 0.76 0.20
1.82 0.64 0.13
1.97 0.51 0.10
2.14 0.40 0.08
2.31 0.30 0.07
2.46 0.22 0.07
2.63 0.17 0.07
2.77 0.14 0.07
2.92 0.13 0.07
3.06 0.12 0.07

I'm using 300ml of developer in a Jobo expert drum for one sheet of 4x5, so I don't think I should be exhausting it. The Pyrocat solution A is about 15 months old, mixed in propylene glycol. The solution B is closer to 2 years. I've got all the ingredients for solution A in tightly sealed jars from when I mixed up the last batch. I'm wondering if I should mix up some new (or maybe take the opportunity to try one of the new variants) and see if that solves the problem. Any thoughts?

Thanks,
Dean

The white light measurement of Pyrocat HD should be less than the blue light or UV light measurement. I good test if you have no way to measure with blue or UV would be to compare contact prints from your DDX and Pyrocat step wedges on graded paper. I'm betting the Pyrocat will not look so underdeveloped there.

It appears that your contrast index for DDX is about 0.86 and for Pyrocat is about 0.52 in white light.

How does Pyrocat go bad?

Well, first it starts hanging out with the wrong kids, then it stays out all night and then...

(Sorry, couldn't resist)

Hi Dean,
I have had exactly the same problem with most of the pyrocat hd I have been using, both from Photographers' Formulary and what I mixed myself. My negatives looked underexposed, though I knew that was not the case. A recent reply by sandy King to someone else with the same problem provided the solution. the problem is with the B solution, either contaminated or too weak. I doubled the amount of solution B so the diution was 1.5:3:100 (as in Clay harmon's article on Unblinking Eye) and got great results. I will be trying 1:2:100 for projection printing soon. Give it a try.

Mark Fernald

DeanC said:

I'm using 300ml of developer in a Jobo expert drum for one sheet of 4x5, so I don't think I should be exhausting it.

Click to expand...

The film is probably not exhasting the developer, but I suspect the oxygen from the air that is inside the Expert Drum is exhausting the developer. Try using a larger volume of developer. I've used up to 1500 mls in my 3010 drum with no problems.

Kirk - www.keyesphoto.com

gainer said:

The white light measurement of Pyrocat HD should be less than the blue light or UV light measurement. I good test if you have no way to measure with blue or UV would be to compare contact prints from your DDX and Pyrocat step wedges on graded paper. I'm betting the Pyrocat will not look so underdeveloped there.

It appears that your contrast index for DDX is about 0.86 and for Pyrocat is about 0.52 in white light.

Click to expand...

The blue light readings look similar, albiet with slightly more density and a steeper curve in Pyrocat. Still the same problem with the first 6 or 7 steps being esentially just base + fog though, at the same exposure that shows useful density in DD-X.

Mark and Kirk,
Thanks, those are both interesting suggestions. I'll shoot two more films under the enlarger tonight and try them at 1:2:100/300ml and 1:1:100/600ml. I seem to recall Sandy mentioning somewhere that 75ml/4x5 sheet should be enough, but I'll give it a go. It'll be several days before my p-aminophenol and potassium carbonate arrive from The Formulary anyway, so I probably won't get to play chemist until this weekend.

Dean

In line with Kino's astute observation, I might add:

"There are no bad Pyro Cats - only bad photographers".

Dean,

Here are my thoughts.

First, unless contaminaed the Stock A and B solutions are very long lived. I have solutions that are well over two years old and are still working perfetly.

The Stock solutions might to bad for the following reasons.

1. Very long storage (over about 1.5 years) may result in some loss of potency of the phenidone. This could take place even if the Stock A remains clear. If this happens the developer will still work, but longer development times will be required.

2. Storage in partially filled bottles will result over time in oxidation of the catechol in Stock A. If this happens Stock A is kaput and should be discarded right away.

3. Contamination of either Stock A or B with even minute parts of the other Stock will result in greatly accelerated aging. This could reduce the life of the developer to weeks rather than months. But this will be visible because both stock solutions will discolor with contamination.

Both Stock A and Stock B should be stored in glass containers for maximum shelf life. If you buy your developer commercially in liquid kit I recommend transfer from the plastic to glass containers.

I hope that covers the issue. However, there may well be things going on that I do not understand, or don't understand well enough.

Sandy

DeanC said:

When Pyrocat goes bad, how does it do it? Does it just stop working or does it lose potency?

I'm doing film tests in the new garage darkroom and I'm seeing some really odd behavior from FP4+ souped in Pyrocat 1:1:100. I just finished the PSP calibration step that Phil recommends using FP4+ in DD-X 1+6 and it landed spot on 2.4, so I'm pretty sure I've got my exposure down right for the tests and I haven't touched the enlarger since calibration. The odd behavior is that the negs developed in Pyrocat look way, way under exposed. Here's an example from the 16 minute dev slice (all readings using white light).

Step DD-X Pyrocat
0.03 2.23 1.37
0.21 2.08 1.26
0.36 1.96 1.18
0.51 1.83 1.10
0.67 1.71 1.01
0.81 1.60 0.93
0.95 1.48 0.84
1.10 1.35 0.74
1.25 1.21 0.62
1.40 1.05 0.47
1.56 0.89 0.30
1.69 0.76 0.20
1.82 0.64 0.13
1.97 0.51 0.10
2.14 0.40 0.08
2.31 0.30 0.07
2.46 0.22 0.07
2.63 0.17 0.07
2.77 0.14 0.07
2.92 0.13 0.07
3.06 0.12 0.07

I'm using 300ml of developer in a Jobo expert drum for one sheet of 4x5, so I don't think I should be exhausting it. The Pyrocat solution A is about 15 months old, mixed in propylene glycol. The solution B is closer to 2 years. I've got all the ingredients for solution A in tightly sealed jars from when I mixed up the last batch. I'm wondering if I should mix up some new (or maybe take the opportunity to try one of the new variants) and see if that solves the problem. Any thoughts?

Thanks,
Dean

Click to expand...

Thanks Sandy. I'm going to mix up some Pyrocat-P and a new batch of Stock-B tonight for use this weekend. I'll try a sheet in each of: my existing batch of Stock-A and the new Stock-B and Pyrocat-P + new Stock B to see if there's any difference.

Well, it wasn't solution B. I mixed up a fresh batch Friday night and just pulled a film out that looks just like the others (first 6-7 steps clear). Maybe it's solution A. A second film is getting a 5m pre-soak right now before getting a bath in some Pyrocat-P.

Exact same behavior in Pyrocat-P. I guess FP4+ is just an ISO 64 film for me. <shrug>

sanking said:

2. Storage in partially filled bottles will result over time in oxidation of the catechol in Stock A. If this happens Stock A is kaput and should be discarded right away.

Click to expand...

Wanted to share info from this weekend while developing negatives using Pyrocat-HD. The P-cat was prepared from fresh chems (obtained from ArtCraft) at the first of August last year. Prepared 1 L of working stock, split between 2 500ml, amber glass bottles. So far so good, have used the first bottle up until this weekend, but noticed that something was going on about a month ago.

What happened...mixed fresh working developer Sat evening, and processed 2 Efke PL100 5x7 negatives and one 120 roll of FP4+. The two 5x7's looked a little underexposed (but I really did not feel they were), then the roll of 120 came out with barely anything on it....hmmmmmmmm!!! I thought maybe I had mixed something up, but decided to dump the working developer, and fix (it was fresh) and weak stop. Got up yesterday morning and processed the other 2 5x7, not sure if they really looked any better and 2 4x5 negative - this is what really got me going. When I first started using P-cat, it was with a bottle that someone gave me - age unkown. The negatives had what I thought was dichronic stain (and had an overall cloudy look to it). Well the 4x5's yesterday had that same look, except is was more of a cloudy look than dirchonic stain. I knew everything was fresh, save the P-cat, so after some running over each step..decided to pull out the other bottle of A & B that were stored (full) when the batch was mixed up.

The results of the last 2 4x5 negatives, blew me away. The apparent density of the fresh developer vs the old stuff (one of the negatives was a duplicate) was definite. There must be at least 1-2 stop difference between the negatives. I have not taken reading of the b+f , but plan to later this week.

So, Sandy your statement above about a partially filled bottle is very true. What surprised me is how gradual the change was - guess I figured it would fail all at once. The other thing that surprised me is the developer seemed to have enough energy to develope part of the Efke films, while the Ilford seemed to need a fresh developer (this is speculation since I did not have another roll of Ilford to develope).

Thanks for the info here Sandy, it helps to understand what happened.

photomc said:

So, Sandy your statement above about a partially filled bottle is very true. What surprised me is how gradual the change was - guess I figured it would fail all at once. The other thing that surprised me is the developer seemed to have enough energy to develope part of the Efke films, while the Ilford seemed to need a fresh developer (this is speculation since I did not have another roll of Ilford to develope).

Thanks for the info here Sandy, it helps to understand what happened.

Click to expand...

I don't know of any way to prove this, but I speculate that what is happening is that the phenidone slowly goes bad in partially full bottle, probably accelerated in some cases by contamination: this would explain the gradual loss of energy, and also the loss of film speed. The pyrocatechin keeps working, but with reduced phenidone the developer is much less energetic. This would definitely explain the loss of film speed, as pyrocatechin by itself is slow acting and does not provide full film speed in Pyrocat without the synergism of a second developer.

An obvious solution to this problem is to split the original Stock A into smaller amounts, and store in glass bottles. This will also prevent contamination of the entire stock, which I suspect happens more than people realize since it is quite easy to do.

Sandy

sanking said:

This will also prevent contamination of the entire stock, which I suspect happens more than people realize since it is quite easy to do.

Sandy

Click to expand...

This is one of the big reasons I switched to disposable pipets for measuring out my developer. They're graduated in 1ml increments and have a 3ml capacity. I use one for stock-a, a different one for stock-b and then discard. Each one might have to dip into the stock solution a couple of times to get enough total chemistry but it doesn't get set down and it doesn't touch any other liquids or containters between dips.

Dean

Something like in this thread happened to me two weeks ago. T-Max 100, at 64, Pyrocat HD 1:1:100, 75F, for 12 minutes, SS Reel, 3 inversions every minute. Only the highlights show in the negs, probably about a zone 3, like as if the film was 5 stops underexposed, which I can't believe. The Pyrocat came from small (4oz, I think) bottles from the Photog Formulary, the smallest size they sell, purchased around Nov last year. I have been doing testing to see how I like it. Just three days earlier, I did some TMax 400 at about a minute longer, which came out as expected. I am careful in measuring with a syringe, and flushing the syringe each pull with running water. The two stock bottles were about a quarter full. I was going to repeat the test to check myself using new Pyrocat, but I thought I would add this to the thread.

Hi Sandy, and Thank You for your response...you confirmed what I suspected, though with much more detail. My quess was some component had started to go bad, just not sure which one. I figure 8 months was pushing the life of one part, in a bottle with that much air. What did encourage me is the fact that the bottle that was full still seemed to be just like a fresh mix bottle. I had taken extra care to not contaminate the part A & B, by using separate transfer pipet for each one and cleaning after each use.

The next batch I make up will be for a stock of 500ml, and separated into 100ml or 250ml bottles since the it seems that I use less than 500 ml in a 8 month period.

Thanks again for your input, and for such a nice product.

sanking said:

I don't know of any way to prove this, but I speculate that what is happening is that the phenidone slowly goes bad in partially full bottle, probably accelerated in some cases by contamination: this would explain the gradual loss of energy, and also the loss of film speed. The pyrocatechin keeps working, but with reduced phenidone the developer is much less energetic. This would definitely explain the loss of film speed, as pyrocatechin by itself is slow acting and does not provide full film speed in Pyrocat without the synergism of a second developer.

An obvious solution to this problem is to split the original Stock A into smaller amounts, and store in glass bottles. This will also prevent contamination of the entire stock, which I suspect happens more than people realize since it is quite easy to do.

Sandy

Click to expand...

For whatever it might be worth, I have never had Pyrocat HD fail in this manner. My usual practice is to mix a liter of stock solution - it takes between 9-months and a year to use it all.

I'm no chemist, but I would suggest two things that may have helped. First, I keep the A solution in an amber glass rather than plastic bottle. I also keep the bottle in a cabinet so it's exposed rarely to light. It's my understanding that most plastics will eventually allow oxygen to exchange with the outside air - something that glass is not supposed to do. It's the oxygen exchange with the outside air that's the big problem - not so much the oxygen in the bottle.

Second, I avoid B solution contamination by not using a B solution. I have computed out the amount of dry carbonate needed for each of the dilutions I use. To make a working solution, I measure out the water, add the A solution, then add the dry measure carbonate. There's no way to contaminate the A solution using that method.

juan