Pyrocat MC Sudden Death!

[Eric Rose]

I will wait to see what PF has to say. There is no chance of contamination in the protocol I use. This is the first time I have experience this type of failure myself and I've gone through a lot of PC-HD over the years.

 

[Ian Grant]

Pyrocatechin is quite unlike other developing agents, I have about a kilo of old stock, dating back to the 60's. Some was in a plastic container still sealed from the supplier and had deteriorated, it was affected by migration through the plastic. The rest is in glass bottles, the developer or rather the fumes from it has attacked the lids of the bottls. The developer (agent) at first appears to be still usable, but in practice causes excess base fog/staining due to the slight decomposition. I should add I don't use this old stock.

Pyrocat, which ever variety, is unusual because there are very few developers we would make up ourselves which are used so highly diluted. So even slight deterioration has a far greater effect. In the past I always used brown glass storage bottle for small quantities of developer. I happened to have some translucent plastic bottle left over from work so used these to sub-divide a batch of Pyrocat, thinking it would keep far longer this way, so I was very surprised to see the developer deteriorating after about 6 or 7 months. There seems to be two reasons, the very slight oxidation of the Pyrocatechin, and the loss of efficiency of the Sodium Metabisulphite/SO2 equilibrium in the solution, both due to the slow migration of gases through the plastic.

One difference I noticed with my Pyrocat in an old Ilford Dev bottle was even under half full and over a year old, there was still a very strong smell of SO2, also not even the slightest sign of oxidation. (I didn't deliberately sniff it - the Pyrocatechin is toxic enough). I hadn't noticed any hint of SO2 with the Pyrocat in the small bottles that had begun to deteriorate. All the raw chemicals are from the same batches.

A few months ago an APUG member who's also a plastics engineer made a post explaining which types of plastic and bottles are most prone to this gas migration. As Sandy says it keeps very well in glass bottles, with or without Glycol, my own experience is it also keeps extremely well in the right type of plastic bottle.

Ian

 

[gainer]

Let me say it again. If you mix A and B before adding the water of dilution, you can expect trouble no matter what the name of your developer concentrate. In particular, if you are using the 1:1:100 dilution, during the time between mixing A with B and adding the 100 parts of water, your solution is 100 times more active than the expected working solution. This means it is also 100 times more subject to aerial oxidation. The B solution is in water even if the A is in glycol.

 

[Tom Hoskinson]

Let me say it again. If you mix A and B before adding the water of dilution, you can expect trouble no matter what the name of your developer concentrate. In particular, if you are using the 1:1:100 dilution, during the time between mixing A with B and adding the 100 parts of water, your solution is 100 times more active than the expected working solution. This means it is also 100 times more subject to aerial oxidation. The B solution is in water even if the A is in glycol.

Yes! I store my stock solutions in amber glass containers with polyseal tops. I add the appropriate amount of the A solution to the (tempered, deionized) water that I use for dilution, mix, then add the appropriate amount of the B solution and mix.

 

[Cor]

Yes! I store my stock solutions in amber glass containers with polyseal tops. I add the appropriate amount of the A solution to the (tempered, deionized) water that I use for dilution, mix, then add the appropriate amount of the B solution and mix.

My routine is as follows (I use a JOBO): I put the appropriate amount of water in the Jobo container in the processor to allow to reach the correct temperature. I add B (the alkali) to the water, load the film, prewash the film in the JOBO, and shortly before the development starts I add the Pyrocatchin (A), mix and pour in the lift to start development.

I guess it shouldn't matter: first A to the water and than B, or vice versa, as long as Gainer already said, do not mix first mix A and B since than the reaction starts..

best,

Cor

 

[Eric Rose]

It seems some have cast aspertions as to my darkroom technique. Let me detail just how I mix up my PyroCat-HD. As mentioned I have used PyroCat-HD for quite some time and have never had a problem. This using the very same techniques and similar storage containers I as am I using now.

I have two measuring containers, one marked A and the other B. The A container has never touched the PyroCat-HD "B" bottle. In fact the closest they have come to each other is probably 4 feet. The same goes for the B measuring container.

I use filtered water which I put into my tank prior to adding any chemicals. I first take down the "A" bottle, take off the cap, put it to one side and then measure the stock solution into the "A" measuring container. Once this is done I pour the measured amount into the water. I then put the cap back onto the "A" bottle, wash "A" measuring container and then put both of them back on the self. The same procedure is done for "B".

I then mix the water with a glass stir rod.

It was suggested to me in what I take to be a rather insulting (to my intelligence anyway) email that I have contaminated the chemicals. Why suddenly after over 30 years of successfully working in a darkroom I have sloppy technique rather mystifies me.

If the containers that PF ships their chemicals in are not suitable for long term storage then this should be clearly identified. If someone was not able to avail themselves of the collective wisdom of this forum then how would one find out that this particular solution will not keep in the original containers if not from the people who make it, sell it and ship it.

I really don't give a rat's behind if someone still has an original batch of the glycol (or whatever it is) version of PyroCat-HD and it still is fine.

I guess I will just have to go out and find some of these magical amber bottles. First time in over 30 years I have had to do so but hey if that's what it takes.

All I know is I will be buying the powdered stuff next time and mixing it myself.

 

[juan]

I have a friend who purchased a Pyrocat/water kit from PF. His procedures are like Eric's - two measuring spoons - one for A and another for B. He suffered complete developer failure. In trying to figure out what had gone wrong, we tried a batch of his A solution and added sodium carbonate powder to the working solution rather than the B solution from PF. The developer then worked perfectly. PF made him happy, so don't take this as an attack on the firm.

I don't know how the B solution could have gone bad, but I saw it happen in this case. And, FWIW, I always store my developers in glass.
juan

 

[gainer]

It seems some have cast aspertions as to my darkroom technique. Let me detail just how I mix up my PyroCat-HD. As mentioned I have used PyroCat-HD for quite some time and have never had a problem. This using the very same techniques and similar storage containers I as am I using now.

I have two measuring containers, one marked A and the other B. The A container has never touched the PyroCat-HD "B" bottle. In fact the closest they have come to each other is probably 4 feet. The same goes for the B measuring container.

I use filtered water which I put into my tank prior to adding any chemicals. I first take down the "A" bottle, take off the cap, put it to one side and then measure the stock solution into the "A" measuring container. Once this is done I pour the measured amount into the water. I then put the cap back onto the "A" bottle, wash "A" measuring container and then put both of them back on the self. The same procedure is done for "B".

I then mix the water with a glass stir rod.

It was suggested to me in what I take to be a rather insulting (to my intelligence anyway) email that I have contaminated the chemicals. Why suddenly after over 30 years of successfully working in a darkroom I have sloppy technique rather mystifies me.

If the containers that PF ships their chemicals in are not suitable for long term storage then this should be clearly identified. If someone was not able to avail themselves of the collective wisdom of this forum then how would one find out that this particular solution will not keep in the original containers if not from the people who make it, sell it and ship it.

I really don't give a rat's behind if someone still has an original batch of the glycol (or whatever it is) version of PyroCat-HD and it still is fine.

I guess I will just have to go out and find some of these magical amber bottles. First time in over 30 years I have had to do so but hey if that's what it takes.

All I know is I will be buying the powdered stuff next time and mixing it myself.

Before you try the new, try replacing the old B solution with fresh to see if that might have lost its poop somehow.

I do not remember anything I wrote that could insult your intelligence. The comment I made about the danger of mixing the A and B before adding water was directed, though not by name, to the the person who stated that he had done exactly that.

 

[hka]

I discoverd in my Pyrocat MC (glycol based) a small dark layer on top of solution A. When I shuttle this a while then I see everywhere dark flakes some zinc to the bottom others are rebuilding a same kind of layer as before. I made it myself from scratch. The development results sofar are good.
Does somebody know what's going wrong here?
Thanks for your help.

 

[gainer]

The problem with putting Metol into a propylene glycol solution is that it doesn't dissolve. Metol has a sulfuric acid "tail" added to make it soluble in water, which keeps it from being soluble in glycol. Removing the tail by use of a small amount of TEA and water makes Metol soluble in glycol, but it may be that even the small amount of TEA (no, not Lipton's or a competitor's) and water caused an accumulative problem.

I found what I think is a better way. 2.5 grams of Metol and 4 grams of ascorbic acid will dissolve in 100 ml glycerol at 250 F and stay dissolved after it cools. This mixture is soluble in glycol along with catechol to make Pyrocat MC without introducing any TEA or water. I told Sandy and I think I remember that he posted that information some time ago, but not before July, 2009 because that's when I told him.

I think the high temperature is necesary because there is in fact a reaction going on. Anyway, it IS necessary. That temperature is far below either the flash point (407 F) or the boiling point (635 F) of glycerol, so it could be obtained in a bake oven if you feel inclined to try it yourself. This MC-glycerol solution may be made in any desired quantity, so that Pyrocat MC can easily be made in small quantities. It may also lead you to other fantastic experiments. Together with an alkali, it could make a non-staining MC developer.

 

[hka]

Mr. Gainer,
Thanks for your information about this.
If I do understand you I take, for example, 10 ml of the glycerol mix, as described above, pour this into the glycol and add the pyrocathechin to make 100 ml of solution A?
And forget the TEA.

Is this CAS# 56-81-5 for the glycerin/glycerol the one I need?
Is saw two versions one is the anhydroes. Is this one preferable?
Many questions I know but I am not a chemist at all...

 

[gainer]

Mr. Gainer,
Thanks for your information about this.
If I do understand you I take, for example, 10 ml of the glycerol mix, as described above, pour this into the glycol and add the pyrocathechin to make 100 ml of solution A?
And forget the TEA.

Is this CAS# 56-81-5 for the glycerin/glycerol the one I need?
Is saw two versions one is the anhydroes. Is this one preferable?
Many questions I know but I am not a chemist at all...

Anhydrous is preferred, and is what you will get under the Leader label at many pharmacies. In any case, heating to 250 F and holding that temperature for a little while will dehydrate it.

The pyrocatecin-glycol mixture may be made first, allowing 10% for the MCG mixture. In your case, you can add the pyrocatechin to glycol to make 90 ml and add 10 ml of the MCG.

 

[hka]

Thanks again this is very helpfull.