What happened to my Pyrocat?
Hi everyone...heh, my first post here after much lurking...
Until yesterday I've been very happy with the negatives from my home-mixed Pyrocat, and was thinking it could become my main developer. My original 100 ml batch, now 2 months old, is about 2/3 gone, and I've been processing some film every weekend for the last few weeks with some really great results. Yesterday, however, my Pyrocat experience suddenly took a turn for the worse.... I shot some 4x5 Classic 200, exposing it at ISO 100 and processing it in my Jobo (1:1:100) as I've been doing, and every one of my negatives looks severly underexposed! The shadow areas are beautifully clear, and there's hardly even any midtone density, but the highlight areas are quite dense....it's as if the film took a sudden dive in effective speed. After racking my brains trying to figure out whether the problem is equipment or exposure related, I came to the conclusion that it must be the developer. So today I shot some test negatives of a contrasty sunlit scene, all at the same exposure, and developed one in Pyrocat and the other in Xtol. The Pyrocat negative has the same look of severe underexposure, while Xtol produced a full negative, consistent with the metering technique I've been using all along.
So what happened to my Pyrocat? One possibility that occurred to me is that the phenidone in the part A has conked out. If I've got the concept right, phenidone is usually superadditive with a second developing agent in a developer, in this case catechol. My negatives still show a brown stain, implying that the catechol is still doing some work, but without the kick of the phenidone, it's only active enough to develop the highlights. Since I mixed the stock solutions using spoon measurements, I'm wondering if I had too little phenidone...enough for the developer to work for a while, but too little to resist decay in the slowly emtying glass bottle. Come to think of it, the diluted solution doesn't have the pinkish or tan color it may have had originally....but I'm not sure.
Do these conclusions make sense to anyone, or has anyone had a similar experience? I keep the solutions in 100ml brown glass bottles, but are there better storage ideas?
Thanks for any ideas....
I had exactly the same result from my first batch of Pyrocat-HD, but right from the start. At the time, I put it down to bad phenidone, since the other chemicals have proved since then to be ok. I don't believe that I made a mistake in mixing.
I need to make the following admission to not following the instructions completely. I made up a stock solution of 5gram phenidone in 100mL of alcohol (95% food grade). I used the appropriate amount of that stock solution
My next batch was using metol (at Sandy's recommended amount) instead of phenidone since I was worried about my source of phenidone. I have been absolutely delighted with the metol version, and I get at least EI 320 out of Neopan 400, which is fast enough. Probably a bit more with minimal agitation.
If the developer was working fine when you first mixed it I believe you should discard the theory that there was too little phenidone. The amount you need anyway is miniscule and in my experience it would not go bad in two months in a partially full bottle.
Originally Posted by j_landecker
The two most likely reasons why the developer may have failed, in mind would be.
1. Somehow either one or both of the stock solutions was contaminated.
2. You failed to add the B solution when mixing the working solution, or the B solution is mislabeled and contains something other than potassium carbonate at the necessary strength.
The very thin negatives that you describe would in fact be what one would expect from using a very weak Stock B solution. This is the accelerator part of the developer that increases the working solution to the pH needed for development, and without it the catechol and phenidone will just sit there and do nothing.
Next time you mix a working solution check the pH if you the means to do so. It should be around pH 10.9 or so.
Thanks for the information and for debunking my chemistry "theories". The solutions were definitely from the right bottles, so I guess that leaves contamination. I use a pipette with a rubber bulb on the end to measure out the concentrates, and although I try to wash it out thouroughly, a few drops of tap water are always left inside. The rubber bulb is also hard to control, and if I suck up too much concentrate, I squirt the excess back into the bottle, but maybe I shouldn't do that! I'll try to mix up some new sol'n B, and see what happens...
It's been my experience that you need to be extremely careful when using pipettes, because contsmination is very easy. Your best recourse is to use pipettes dedicated to each solution, or small graduated cylinders, again dedicated to each solution. I try never to put excess stock solution back into the bulk container and never had a problem with contamination of this type.
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I have discovered that the best way to avoid contamination is to get a graduated cylinder small enough to accurately measure small amounts of chemistry. I have a couple that measure 10ml in (1cc?) increments.
if you want to use pipettes, the best procedure is to have several on hand and never use the same one twice when measuring chemicals. This way you are sure you have a clean one for each different solution. Wash them up when you are done and you are ready to go next time.
"Fundamentally I think we need to rediscover a non-ironic world"
if you want to use pipettes, the best procedure is to have several on hand and never use the same one twice when measuring chemicals.
Some months ago I purchased in UK a box of graduated plastic ones and got 500 for about the equivalent of $25.
Cogito, ergo sum.
I use 10mL pipettes with some rubber bulbs that have a valve at the top (for expelling some air) and below (for controlling the amount of liquid sucked up). They are from a lab supplier. The valves are simply moulded into the bulb, and release very gradually with pressure from finger and thumb, so the movement of liquid up the tube is slow and steady if you want it to be.
Smaller ones are available, and would be adequate for me in terms of volume, but they're harder to rinse because of their narrowness.
Originally Posted by PJC
I have been using the same pyrocat premix solutions for 8 months with no let-up in effeciency. For dispensing of the 2 solutions I use childrens medication syringes which are calibrated to 5ml (in 1ml increments) and cost under a £1 each. You can take them apart for cleaning (and drying) plus they come with a rubber stopper for the top of the (100 ml medicine) bottles that use. I have labelled each one so reduce risk of contamination. This works very well for me.
It is not tradition that secures the survival of our craft, its the craft that secures the survival of our traditions.
i use those little medication syringes too, have done with all of the 2 solution developers I have used with no cross contamination at all - and the pharmacist gives me them for free!