Pyrocathecol, catechol age

[haryanto]

anybody know how long we can keep cathecol, and what the best way to keep it long lasting, thanks

haryanto

 

[haryanto]

I've read somewhere in this forum, that we can dissolved it in polypropylene glycol to keep it long lasting, but if not how long it will be getting brownish

 

[jim appleyard]

I've got some 3 year old cat that looks pretty brown, like chocolate. IMO, it's not quite dead, but very ill. I made some Pytocat HD with it and negs were quite thin. It could maybe be used for a warmtone paper dev, but I would think it's tray life be would be one short session.

If you had to store it dry, I would try glass jars, and then put in in a freezer that's not being used for food.

 

[haryanto]

I bought cathecol last year in April from Artcraft, I stored it in glass bottle, and seal it with plastic tight, there's no sign changing color to brown, but I just bought from chemical store in plastic bottle (with trademark "merck") it slighty brownish, I have not try it, but I hope it's still work

thanks Jim

 

[Tom Hoskinson]

I've read somewhere in this forum, that we can dissolved it in polypropylene glycol to keep it long lasting, but if not how long it will be getting brownish

3+ years ago, I made up a stock solution of catechol dissolved in propylene glycol. The solution has not changed color or activity over the 3+ years.

I have obtained the same result with Pyrogallol, Hydroquinone and Phenidone stock solutions in propylene glycol.

Metol isn't readily soluble in propylene glycol unless you first use Pat Gainer's procedure to create the Metol Base.

 

[Bruce Osgood]

3+ years ago, I made up a stock solution of catechol dissolved in propylene glycol. The solution has not changed color or activity over the 3+ years.

I have obtained the same result with Pyrogallol, Hydroquinone and Phenidone stock solutions in propylene glycol.

Metol isn't readily soluble in propylene glycol unless you first use Pat Gainer's procedure to create the Metol Base.

To what percent dilution do you make a stock glycol dilution of these chemicals? How does that percent, say, propylene glycol-Pyrogallol translate into grams per liter for a working solution?

 

[Tom Hoskinson]

To what percent dilution do you make a stock glycol dilution of these chemicals? How does that percent, say, propylene glycol-Pyrogallol translate into grams per liter for a working solution?

Bruce:
1. My Phenidone Stock Solution contains 0.1 gram Phenidone per ml
2. My Pyrogallol Stock Solution contains 0.5 gram Pyrogallol per ml
3. My Pyrocatechol Stock Solution contains 0.5 gram Pyrocatechol per ml
4. My Hydroquinone Stock Solution contains 0.5 gram Hydroquinone per ml

For Example:

To make 500 ml Pyrocat A stock solution
Take 350 ml Propylene Glycol at Room Temperature
Dissolve 1 g Phenidone (i.e. 10ml Phenidone Stock Soln)
Dissolve 25 g catechcol (i.e.50ml catechol Stock Soln)

Add sufficient Propylene Glycol to make 500ml

 

[haryanto]

thank you very much Tom for your info

 

[Bruce Osgood]

Tom,

I'm sorry but I don't seem to grasp your answer.

Do you not make a stock solution of phenidone using proplene glycol that would only contain phenidone?

If you do, and this is what I think you were getting at, to what percent solution is it? And how would this translate back into grams as part of the stock solution of Part A? Are you making a liter of .01 percent solution, wouldn't that be adding .001 grams phenidone to 1000 mL P-G?

Maybe I got this all wrong so excuse me.

 

[Jed Freudenthal]

Pyrocatechol will be stable for a long time (years) . Even if it is light brown or tan, it can be used. I once dissolved it in propylene glycol. Then it is unstable. In the first few days the development activity will increase and thereafter it will decrease again. Anyway, byproducts are apparently created.
I use the pyrocatechol straight, as they do in Europe for over one century. A fresh pyrocatechol often has a strong phenolic odor. When the pyrocatechol becomes older, the odor will disappear. If you do not like that odor or want to be sure for toxic reasons, just weigh and dissolve the pyrocatechol (on a safe place) outside if you do not have a fume hood.

Jed

 

[Tom Hoskinson]

Tom,

I'm sorry but I don't seem to grasp your answer.

Do you not make a stock solution of phenidone using proplene glycol that would only contain phenidone?

If you do, and this is what I think you were getting at, to what percent solution is it? And how would this translate back into grams as part of the stock solution of Part A? Are you making a liter of .01 percent solution, wouldn't that be adding .001 grams phenidone to 1000 mL P-G?

Maybe I got this all wrong so excuse me.

No problem, Bruce

I find it easiest to think in terms of the amount of the chemical in grams per ml of solution because that is really what I need to know in order to make up a developer.

Pyrocat example: In order to make up a liter of (propylene glycol based) Pyrocat Stock A, I will need to dissolve 2 grams of phenidone in 100ml or so of propylene glycol and then add sufficient additional propylene glycol to make a total solution volume of 1 liter.

2 grams divided by the 1000ml total solution volume = 0.002 grams of phenidone per ml of Stock A



My standard Phenidone Stock Solution contains 0.1 gram of Phenidone per ml.

to make up this solution I dissolved 10 grams of Phenidone in about 50ml of Propylene Glycol and then added sufficient additional Propylene Glycol to make a total solution volume of 100ml. Thus, I have 0.1 grams of phenidone for each ml of solution: 10/100 = 0.1

this is often called a 10% solution

To get the 2 grams of phenidone I need to make up a liter of Pyrocat A, I would need to use 20ml of my .1gram/ml phenidone stock solution.

 

[Black Dog]

I have some 11 year old catechol{in powder form} which still works great!

 

[Bruce Osgood]

Tom,

I GOT IT! Thank you for the extra effort.

 

[Tom Hoskinson]

Tom,

I GOT IT! Thank you for the extra effort.

Your'e welcome, Bruce!

 

[haryanto]

Pyrocatechol will be stable for a long time (years) . Even if it is light brown or tan, it can be used. I once dissolved it in propylene glycol. Then it is unstable. In the first few days the development activity will increase and thereafter it will decrease again. Anyway, byproducts are apparently created. ......

Jed

this is really interesting Jed, somebody say if cathecol dissolved in PG will prolong the lifeshelf,

so if we mix developer with PG (propylene glycol) such as pyrocat will it become unstable? and why?

thanks

 

[Tom Hoskinson]

this is really interesting Jed, somebody say if cathecol dissolved in PG will prolong the lifeshelf,

so if we mix developer with PG (propylene glycol) such as pyrocat will it become unstable? and why?

thanks

The simplest explanation for the developer behavior that Jed described is contamination of the solution.

Otherwise, Jed's statement is completely contrary to my own testing experience and the experience of many others. For example, I have a batch of Pyrocat-HD that I mixed up in Propylene Glycol in 2004 that is still fully active and still produces predictable and repeatable results. I periodically test it by mixing up a batch of working developer 1+1 +100 dilution ratio (I use fresh B solution and the A solution mixed in PG in 2004). I then develop a test film exposed to a density step wedge under controlled time/temperature/agitation conditions. After development, fixing, washing and drying; I read and record the density steps with my densitometer.

All of my Propylene Glycol stock solutions (Phenidone, Pyrogallol, Catechcol and Hydroquinone) that I mixed in 2004 also are still fully active.

I periodically perform quick activity tests of all my developer stock solutions by dissolving a few ml of the PG solvent stock solution in some water, then I mix in a few grams of Sodium Carbonate and soak a strip of exposed film in the solution and record the time required to blacken the film. I also read and record the maximum density achieved.

 

[Jed Freudenthal]

this is really interesting Jed, somebody say if cathecol dissolved in PG will prolong the lifeshelf,

so if we mix developer with PG (propylene glycol) such as pyrocat will it become unstable? and why?

thanks

Catechol, pyrogallol ( with and without functional groups) etc are chemically structural related and many of them 'developing power'. Extensive studies were made in Germany on pyrogallol. Reports show pyrogallol related compounds which more interesting features than pyrogallol itself( like higher development power).
My results of my dissolving experiments on catechol indicate a similar behaviour. Catechol is converted ( partially) in other compounds with developing power. Eventually there is a stabilization in development power. The end product is stable with respect to development power, but the identity of the developing agent is for me unknown. And that is what I do not like (as a chemist). There is more to a developer than developing power.

Jed

 

[sanking]

this is really interesting Jed, somebody say if cathecol dissolved in PG will prolong the lifeshelf,

so if we mix developer with PG (propylene glycol) such as pyrocat will it become unstable? and why?

thanks

My experience in dissolving pyrocatechin in proylene glycol in the Pyrocat-HD and Pyrocat-MC formulas is that the resulting developer is very stable over a very long period of time. I first mixed a Pyrocat-HD A solution in glycol about 2.5 years ago, and have on hand at this time a fairly large amount of the original solution which I kept for control and comparison purposes. Results from this solution are for all practical purposes identical to results from fresh solutions of Pyrocat-HD, mixed in either glycol or water. In other words, there has been no change at all in the working property of the A solution mixed in glycol for over 2.5 years.

Sandy King

 

[haryanto]

Catechol, pyrogallol ( with and without functional groups) etc are chemically structural related and many of them 'developing power'. Extensive studies were made in Germany on pyrogallol. Reports show pyrogallol related compounds which more interesting features than pyrogallol itself( like higher development power).
My results of my dissolving experiments on catechol indicate a similar behaviour. Catechol is converted ( partially) in other compounds with developing power. Eventually there is a stabilization in development power. The end product is stable with respect to development power, but the identity of the developing agent is for me unknown. And that is what I do not like (as a chemist). There is more to a developer than developing power.

Jed

So Jed, is that meant there's better to keep the catechol in mix all the the stuff (i.e pyrocat) than to keep it alone in PG?

thanks Jed, Tom, And Sandy for generous to share the info

 

[Jed Freudenthal]

So Jed, is that meant there's better to keep the catechol in mix all the the stuff (i.e pyrocat) than to keep it alone in PG?

thanks Jed, Tom, And Sandy for generous to share the info

Yes, I weigh and mix the catechol just before the development process takes place. Nothing can and is more reproducible than that. And I know I work with catechol. I usually weigh my catechol (1.4 g) just before the development process. I dissolve the catechol in water ( this might take two minutes). Then I add a very small amount of sodium sulfite and after that I add the alkali (potassium carbonate). But you can prepare, say 10 portions, and put them in small plastc bags or so, to be used in future development rounds. Anyway, whether you weigh the catechol just before development, or you put it in a solvent like propylene glycol, you have to take your precautions, because it is a toxic substance. The advantage of catechol over pyrogallol is, that it will give less dust. Although the vapour pressure of catechol is low, there might be some vapor around. But the vapor is heavier than air. So, make sure to weigh on a small table in a ventilated area in a way that the vapors can disappear to the ground. And, of course, put the spoon in a quit way in the chemicals.

Jed

 

[pauldc]

And do I understand it correctly that by making a Pyrocat A solution in proylene glycol as Tom explained in this thread then I only need to use catechol and phenidone and I can dispense with the potassium bromide and sodium metabisulphite that I would normally use when making the A solution in a water base?

If so, this would be much simpler as well as having a good lifespan

 

[Jed Freudenthal]

And do I understand it correctly that by making a Pyrocat A solution in proylene glycol as Tom explained in this thread then I only need to use catechol and phenidone and I can dispense with the potassium bromide and sodium metabisulphite that I would normally use when making the A solution in a water base?

If so, this would be much simpler as well as having a good lifespan

This thread is about the lifespan of catechol. I am not referring to Pyrocat A. I just describe the way I make a catechol developer, I also published on the APUG site under 'high definition developers, staining and non-staining'. The catechol developer published on the APUG site is a modification of a recipe that has been used in Europe during may be a century. In the Netherlands we had an APUG workshop where the participants did the mixing of the chemicals and compared them with a variety of other developers.

Jed

 

[sanking]

This thread is about the lifespan of catechol. I am not referring to Pyrocat A. I just describe the way I make a catechol developer, I also published on the APUG site under 'high definition developers, staining and non-staining'. The catechol developer published on the APUG site is a modification of a recipe that has been used in Europe during may be a century. In the Netherlands we had an APUG workshop where the participants did the mixing of the chemicals and compared them with a variety of other developers.

Jed

The discussion about Pyrocat-HD arose from your assertion that pyrocatechin mixed in propylene glycol is not stable. If that assertion were true it would raise questions about the stability of Pyrocat-HD, and all other pyrocatechin based formulas mixed in glycol. I have lots of empirical evidence that pyrocatechin solutions mixed in glycol are very stable, including the fact that a numer of formulas that I mixed well over two years ago in glycol solutions are working today just as they did when first mixed. That includes both Pyrocat-HD and a number of other formulas that contain pyrocatechin.

Sandy King

 

[pauldc]

This thread is about the lifespan of catechol. I am not referring to Pyrocat A.
Jed

Sure Jed, but Tom and Sandy were making some comments about the topic in relation to Pyrocat. Often the best threads go off in several inter-linked and really interesting directions at once and this can only aid learning.

One other thing I am interested to clarify is that it seems from the thread that propylene glycol can dissolve all these various chemicals (catechol, phenidone etc) at room temperature. Have I understood this correctly?

Thanks everyone

 

[sanking]

One other thing I am interested to clarify is that it seems from the thread that propylene glycol can dissolve all these various chemicals (catechol, phenidone etc) at room temperature. Have I understood this correctly?

Thanks everyone

Paul,

I will only speak to dissolving the chemicals in Pyroat-HD. Sodium metabisulfite and potassium bromide do not dissolve well in propylene glycol at room temperture. In fact, for them to dissolve well requires heating the glycol to tempertures of around 200F. I would rather avoid such high temperatures and recommend mixing Pyrocat-HD in glycol in the following way

1. First measure out all of your chemicals and weigh them. We will assume 1000ml of stock solution, so that would be 50g of pyrocatechin, 2g of phenidone, 10g of potassium bromide and 20g of sodium metabisulfite.

2. Add the pyrocatechin to about 750ml of glycol at 150F, and stir until dissolved. Then add the phenidone, and stir until dissolved.

3. Now, add the potassium bromide and sodium metabisulfite to 90ml of very hot water at about 150F and stir until dissolved.

4. Mix the bromide/metabisulfite solution with glycol.

5. Now add glycol to top off at 1000ml

Pyrocat-HD stock solutions prepared this way are very stable. As I indicated otherwise, I have a control stock that was mixed about 2.5 years ago and it works just like a fresh solution.


Sandy King



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