• Welcome to Photrio!
    Registration is fast and free. Join today to unlock search, see fewer ads, and access all forum features.
    Click here to sign up

Mixing Pyrocat Solution B

El Gringo

Subscriber
Allowing Ads
Joined
Oct 20, 2006
Messages
147
Location
Wales
Format
Medium Format
In the next few days I plan on mixing my first ever batch of Pyrocat-M from raw chemicals. Although there are loads of great resources concerning Pyrocat I just wanted to clarify the procedure for mixing the 75% Potassium Carbonate solution.

Most other formulae (including Pyrocat solution A) require that you preheat the water to around 50 degrees C before mixing in dry chemicals, but nothing is mentioned next to the water in the Pyrocat recipe. Does this mean that I should just start with room temperature water? If so is this due to the exothermic reaction that happens when you add the Potassium Carbonate?

Cheers
 
Rhys

You will not disolve the carbonate at room temperature, the warmer the better. I would also say that before you commit any film that is important to you to Pyrocat M, test, test, and test again. I do not wish to scaremonger, but I had a lot of problems with Pyrocat M, including pin holes, air bells, and in some cases, signs of uneven development, and all of this after some serious testing. I should also add that I have never had any of these problems with any other developer in a good few years now.

I never did get to the bottom of why it was happening, so unfortunately I gave up on using it, which was a huge regret because I found it gave me such a beautiful negative, bar the problems, far sharper than Pyrocat HD, and a better stain too.

Best of luck, and do let us know how you get on.

Stoo
 
My experience with my pyro formula of choice, PMK is that the B - a saturated solution of Kodalk, should be mixed with distilled water (not just Reverse Osmosis), and even then it may not stay in solution.

I mixed mine with room temp water , knowing that there would likely be parts of the powder that would not dissolve (there were). So I shake before use, and the undissolved powder is at least uniformly in suspension when measuring B off.

I feared if I went hot water to dissolve then on cooling the Kodalk might have crystalized out, and then it would might not be uniform when shaken if the crystals caked on the bottlom of the storage bottle.

I'm not a chemist; this is just my two cents worth of experience.
 
Rhys

Just to add, because dissolving the 100g of Potassium Carbonate in 100ml of water can be problematic, a good tip I was given was to dissolve 20g in 100ml of water, and use the developer at 1:5:100, instead of the usual 1:1:100.

Stoo
 

You might want to try Pyrocat MC, which uses the same B solution but uses propylene glycol as solvent of the A and has ascorbic acid in place of a sulfite. I'm sure Sandy King has posted the recipe. It is also possible to make a solution of sodium metaborate and sodium hydroxide that can substitute for the K2CO3 solution.
 
You start with about 700 ml water at room temperature and slowly ad 750 g potassium carbonate under constant stirring. The reaction is exothermic so the solution will warm up anyway. The final solution is more or less saturated so you will have to fill the volume to 1 liter to get all the carbonate dissolved. Should not be a problem.
 
I found my recipe for Pyrocat MC.

100 ml glycerol
4 grams ascorbic acid
2.5 grams Metol
Heat to 250-300 F.

Add about 750 ml of warm propylene glycol and 50 grams of pyrocatechin (AKA catechol). Bring the volume to a liter. This is the pyrocat MC stock solution. For starters, you can try the published procedures for Pyrocat HD.

The glycerol reacts with the H2SO4 on the Metol to make a glycerol sulfate which is soluble in propylene glycol. Medicinal glycerol (also called glycerine) is about as anhydrous as it can be and is available in small amounts.
 

Thanks Patric

Would you be kind enough to elaborate further on the mixture/volumes for the sodium metaborate and sodium hydroxide 'B' bath please. It is something that I would like to try before progressing on to another developer.

Kind Regards

Stoo
 
Stoo, since our discussion in Cornwall a few days ago I've had to make up a fresh batch of Pyrocat Solution B. I found the bulk (over 95%) of the Potassium Carbonate dissolved easily in water at 18-20° C with plenty of stirring and I just needed some luke warm water (50° C approx) to dissolve the rest.

I used to suffer from air-bells in Turkey with Pyrocat, but I found this was partially due to the water, there are two ways to eliminate the problem, both of which are used in commercial developers. The first is the use of a wetting agent, the second adding EDTA or Sodium Hexametaphosphate (once sold as calgon). Dr Andresen of Agfa wrote about avoiding air-bells in the early 1900's and all the major companies patented compounds to help eliminate them.

My own approach has been to add a very small amount of wetting agent to Part A, this is a few drops and entirely eliminates the air bell problem, but too much will cause foaming so it's a fine balance.

Ian
 
I seem to be in the minority, and I assume it's due to my water, but I have no problems mixing 100g of Potassium Carbonate in 100ml of water. I use tap water at 21ºC and just dump in the carbonate and stir a bit–I've been doing it that way for several years.
 
Maybe I missed something but Part B is 750 grams Potassium carbonate in 1 litre of water, that should dissolve easily as the saturation point is is 112 g/l at 20ºC.

Sometimes there's a few obstinate crystals that need warmer water to dissolve quickly but they'd dissolve overnight @ 20º C.

Ian
 
Thanks all for the great replies, the chemicals all turned up today so I should have them mixed sometime tomorrow or Monday. I'll report back when I've developed the first batch of negs.
 


I believe that originally Sandy KIng specified 1000g/liter, but then changed it to 750g because some people had trouble dissolving more. Whichever is technically correct I have been doing it this way for so long with such great results I see no reason to change now.
 

Ian

I hear you regarding the wetting agent, and I am pretty confident that it would do the trick, either that or a little bit of Isopropyl, but my concerns are mainly with the pin holes. I do find it rather strange that I have never had this problem with any other developer, even Pyrocat HD, and that there is probably many users also using Pyrocat M daily, without issue. It's just one of the many mysteries of photography. I just stood to attention when Patric Gainer suggested a different 'B' bath, the reason being that I feel that the carbonate is probably the cause of the pin holes, after reading between the lines in the cook book, and conversations I have had with both yourself, and others, and if not, at least it is another variable that I have taken out in my process of elimination.

All that said, I am happy with what I am using at the moment and would not wish to return to a developer that causes me issues, as my photographic journeys are too distant and few and far between to be screwing up any more negatives.

I will be happy when I have finished developing my own staining developer

Cheers

Stoo
 
El Gringo said:
Thanks all for the great replies, the chemicals all turned up today so I should have them mixed sometime tomorrow or Monday. I'll report back when I've developed the first batch of negs.
Click to expand...


Good luck Rhys

I am sure you are gonna love your negs. And if they are a success, I will send you my film to process

Best

Stoo
 
Mixed the Pyrocat yesterday and managed to develop three negs this morning. They're still drying but on first inspection all looks pretty good, especially since I just kinda guessed the dev time (12 1/2 mins for Fomapan 100); weird getting brown negs!

I hope to get some test prints done in the next few days and will post some up when they're done.

Thanks again for all the help.
 
Solution B of Pyrocat, both -HD and -MC, is a 75% solution of potassium carbonate. This should mix easily as the solubility of potassium carbonate is well above 115% at room temperature. If your solution does not go into solution readily you most likely have something other than potassium carbonate, perhaps sodium carbonate or a mixture of sodium and potassium carbonate.

Any of the problems that I have seen reported over the years from the use of Pyrocat are resolved with the use of distilled, ionized or purified water. Ian has noted other solutions but given the cost of good water this would always been my path to avoid problems, whether with Pyrocat or any other developer.

It should be noted that Pyrocat in normal dilution of 1+1+100 contains less reducer than 99.9% of all formulas. This is one of the reasons for its outstanding acutance with normal agitation, but can be a negative when the working solution is mixed with water of questionable quality.

Sandy King
 
I have had no problems with mixing Pyrocat HD. Then again, I mix the solutions with purified ( distilled ) water available at a very reasonable price at the Publix markets here in Florida...
 
I would just like to point out that my previous posts in this thread were made with the understanding that it was still the norm to mix 100g of Potassium Carbonate in 100ml of water, and I was unaware that an adjustment was made to the formula. I still stand by my words in that 100g of Pot Carb is a pig to dilute in 100ml of water, at least that is my experience.

Reading between the lines of Sandy's post, I have always mixed my chemicals with R.O water, not distilled, de-ionized or purified, as mentioned. Perhaps this is an avenue that I should explore. And to end, although this is not my thread, I would like to thank all involved for their input, as even after a long time now mixing my own developers, I am still learning, so thank you.

Best

Stoo
 
I just mixed up a batch yesterday.
I only mix 100ml of A and B at a time.
I had no trouble getting the 75mg Potassium Carbonate to go in to solution with about 80ml of distiled water.

The last time I mixed some up I did not have enough Potassium Carbonate so I used Sodium Carbonate in the equivalent amount. Once I realized it would not go in to solution I used 5 times the volume of water then just used 5 times the normal amount of solution B when developing.
 

Excuse the delay. During my stay in hospital many of my records were misplaced by well intentioned "Picker-uppers." Some went into the circular file.

I believe a saturated metaborate (AKA Kodalk) solution at 20 C will work. Do not be concerned about the distinction some make between "4 mole" and "8 mole" metaborate. The 4 mole becomes the 8 mole at temperatures above 53.6 C without any change of weight or appearance by combining 2 4 Mol to make 1 8 Mol.

Somewhere on APUG I described my experiments with the metaborate B, but I'm blessed if I can find it now. Perhaps Sandy King will know.
 
Just to update everyone I've made a couple of 8x10 test prints on my proof paper. they printed really easily at grade 2, which is good considering I guessed the development time! I've attached some scans in case anyone wanted a peak (any dust is from the quick scanning, its not on the real prints).



 
To me the prints look good, but I'm not an expert of course. They seem very sharp to me.
 

Pat,

As I recall you mixed one of the hydroxides with metaborate to get the pH needed for pyrocatechol. My experience is that a saturated metaborate solution by itself does not give high enough pH for the Pyrocats, but it has been a long time since I did the tests and I could be mistaken, or have made some kind of mistake in the earlier tests.

Sandy King
 
You must log in or register to reply here.
Menu
Log in
Register