PYROCAT-HD NOTES

Would like to share a few notes on the use of Pyrocat-HD, and some modifications to the formula.

First, let me comment that the Pyrocat-HD formula is in the public domain, and although it is sold through various sources in the US and in Europe I am not involved personally involved in those enterprises.

OK, here are the notes.

A. SLIGHT CHANGE IN THE FORMULA
If you are currently mixing your own Pyrocat-HD stock solutions from scratch I have made a slight change in the formula for Stock Solution A. When mixing from scratch I am now recommending only 0.1g of potassium bromide for 100ml of Stock A, (or 1.0g for 1000ml of Stock A). In some situations the change will result in a very slight improvement in film speed, with no adverse results. I will communicate this change very soon to the folks at B&S and PF who supply Pyrocat-HD in kit form. However, this is a very minor change so don't throw away your old Pyrocat-HD kits as it would take some very good sensitiometry to see the difference.

B. MIXING STOCK SOLUTIONS WITH GLYCOL
On mixing Pyrocat-HD in Propylene Glycol. As many of you know, mixing Stock Solution A of Pyrocat-HD in Propylene Glycol provides stability of the stock solution on the order of years, similar to HC-110. Here is a very safe way to do this, measured for the 1000ml kit.

1. Weigh out all of the chemicals for Stock A. 50.0g of pyrocatechin, 10.0g of sodium metabisulfite, 2.0g of phenidone and 1.0g of potassium bromide.

2. Pre-heat in a water bath 750ml of propylene glycol to about 150F.

3. Add the pyrocatechin to the glycol and stir until dissolved. Should take no more than about a minute.

4. Now add the phenidone and stir. Should dissolve completely in about a minute.

5. Add the bromide and sodium metabisulfite to about 50-75ml of hot water at about 120F. Stir until completely dissolved, then mix with the propylene glycol solution.

6. Top off the solution with glycol to 1000ml

Once you do this a couple of times you will find it just as easy as mixing Stock A in water. Should you be concerned about the small amount of water in the solution? Absolutely not. Pat Gainer, who is the expert on these type of solutions, has recently recommended this type of mixing for his PC-TEA formula, and if he is satisfied with the stability so am I.

C. NEW PYROCAT TYPE FORMULA
Since the Pyrocat-HD formula was introduced in the late 1990s I have experimented with many variations for specific purposes. For example, I added a small amount of ascorbic acid which made the formula much more active, which I called Pyrocat+. I also experimented with extra sulphite in the formula to make the formula non-staining. Most of the notes of these experiments were sent to the AZO forum.

However, over the past six months I embarked on a different path of experimentation with the Pyrocat-HD formula and have recently come up with something that I consider an entirely new developer. It involves the use of a regenerative reducer other than phenidone, and the use of another restrainer. The new formula is not better than Pyrocat-HD, but it is different in a number of ways. I have done a lot of sensitometric testing of this formula and know it can do in terms of EFS and curve with a number of films. However, evaluating grain and sharpness is a highly subjective action, and for that reason I am looking for 3rd party comments.

I know that there area a number of long-time Pyrocat-HD users on this forum. For those interested I would like to send you a 100ml bottle of the modified Stock A, which I will call for the moment Pyrocat2, for your evaluation. You can use your regular Stock B solution with this formula. I am primarily interested in personal feedback on results, but anyone who tests the variation should feel free to express their opinion here or elsewhere about it.

OK, if interested please contact me off list, at sanking@clemson.edu. I am primarily interested in current users of Pyrocat-HD, since these are the persons who could offer a good opinion of the new formula compared to the old

Sandy.

Sandy, I'm curious about the numbers I have for the existing formula vs. the new formula. I've been using the PF kits and am happy with results, but a similar developer would be interesting as well. I have only a year of experience with pyrocat-hd, so I'm not your best choice for an evaluation. tim

Tim,

I will provide the formula once I have made a few final adjustments and get some feedback from a few users. BTW, I have received about as many offers to test the new formula as I was hoping to get. However, it will probably be several weeks before I send out the smaples because I want to mix with fresh chemicals and then run a few more sensitometry tests to verify consistency with the previous results.

Sandy

noseoil said:

Sandy, I'm curious about the numbers I have for the existing formula vs. the new formula. I've been using the PF kits and am happy with results, but a similar developer would be interesting as well. I have only a year of experience with pyrocat-hd, so I'm not your best choice for an evaluation. tim

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Sandy thanks for all the good work you have been doing. I personally find Pyrocat-HD to be the single best all around developer in terms of image quality. I don't perform density/sensitometry readings or anything remotely resembling scientific testing so I would be a poor evaluator lol. All I know is that the current stuff works great! I do look forward to future reports by yourself and others. Here's hoping your new project is successful although I hope that the current version of Pyrocat will still be produced by the formulary.

sanking said:

However, evaluating grain and sharpness is a highly subjective action, and for that reason I am looking for 3rd party comments.

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Sandy - I happen to have a set of both the positive and negative chrome on glass slide USAF 1951 resolution targets at this time - for making contact print resolution test. If you would like, I can do some tests with them. I've been able to get my technique with Fuji Acros good enough to record about 120 or so line pair per mm for the negative target. (Fuji lists the resolution at 200 lp/mm for high contrast targets.)

Let me know if you are interested.

Kirk

PS - could you post the current version of Pyrocat HD to have it with this thread. Also, would you call this revision 2.0 or something for Pyrocat?

Kirk,

Yes, I would be interested in the resolution test. Have you compared the resolution of any other developers? My own attempts to do this suggest that unlike sharpness, which can be enhanced significantly by choice of developer, the resolution of films is rather fixed and can not be changed much by choice of developer.

The current version of Pyrocat-HD, which incorporates the change mentioned at the beginning of this thread, is as follows. I am not going to call it a revision because the small change made is fairly inconsequential in terms of results.

Pyrocat-HD

Stock A
Distilled Water -- 750ml
Pyrocatechin -- 50g
Phenidone* -- 2.0g
Sodium metabisulfite -- 10g
Potassium bromide -- 1.0g
Water to 1000ml

*Mix first in a small amount of alcohol, then add to the stock solution.

Stock B
Distilled Water -- 750ml
Potassium carbonate -- 750g
Add slowly while stirring the potassium carbonate to the water. Should make a total of about 1000ml. There will be an exothermic reaction that will cause the solution to warm up as you mix it.

You can use a variety of dilutions. I generally recommend 1:1:100 for silver papers and 2:2:100 for alternative printing but other dilutions may be better for specific purposes, for example 1.5:1:150 for stand development, 5:3:100 for very low contrast scenes with alternative processes, etc.

Some of the variations on the original formula which some have tried include using metol in place of phenidone, at about 15X-20X the amount of phenidone, adding extra sulfite to make the developer non-staining (does not take much), adding ascorbic acid to make the solution faster working, and using a Stock B solution of 10% sodium hydroxide solution in place of the 75% potassium carbonate solution. Any of these variations might be useful in certain circumstances.

Sandy

Kirk Keyes said:

Sandy - I happen to have a set of both the positive and negative chrome on glass slide USAF 1951 resolution targets at this time - for making contact print resolution test. If you would like, I can do some tests with them. I've been able to get my technique with Fuji Acros good enough to record about 120 or so line pair per mm for the negative target. (Fuji lists the resolution at 200 lp/mm for high contrast targets.)

Let me know if you are interested.

Kirk

PS - could you post the current version of Pyrocat HD to have it with this thread. Also, would you call this revision 2.0 or something for Pyrocat?

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Hi Daniel,

Thanks for your generous comment. I don't think there is any reason to worry about losing the current version of Pyrocat-HD so long as there are people interested in purchasing it.

I do want to make it clear that my interest in having a few other people evaluate the new developer is for visual impressin of grain and sharpness and overall image quality, not for sensitometric testing. I have some experience with testing and can do the basic ensitometry myself.

Sandy

Daniel Lawton said:

Sandy thanks for all the good work you have been doing. I personally find Pyrocat-HD to be the single best all around developer in terms of image quality. I don't perform density/sensitometry readings or anything remotely resembling scientific testing so I would be a poor evaluator lol. All I know is that the current stuff works great! I do look forward to future reports by yourself and others. Here's hoping your new project is successful although I hope that the current version of Pyrocat will still be produced by the formulary.

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Sandy,
What kind of alcohol do you dissolve the phenidone in?

I use plain 90% isopropyl alcohol. All you need is a very small amount. Just add it to the phenidone and grind up into a paste.

Sandy

colrehogan said:

Sandy,
What kind of alcohol do you dissolve the phenidone in?

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sanking said:

I use plain 90% isopropyl alcohol. All you need is a very small amount. Just add it to the phenidone and grind up into a paste.

Sandy

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Sandy,

I use a little more alcohol then you do by your description...I have found raising the temp of the solution with a 5-8 second zap in a microwave helps greately in getting the phenidone into solution.

Donald Miller said:

Sandy,

I use a little more alcohol then you do by your description...I have found raising the temp of the solution with a 5-8 second zap in a microwave helps greately in getting the phenidone into solution.

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When I mixed up my first batch in glycol last year, I had just picked up a stirrer hotplate on eBay. You can get them in decent shape fairly cheaply and it makes heating and mixing loads easier. Highly recommended.

I'm with DeanC... A magnetic stir heater is about the handiest darkroom device one can own, they're cheap (used), they don't cavitate air into your chemistry and they free you from manual stir duties while maintaining a proper temperature. I was due for a new batch of PyroCat-HD today and decided to mix the PG version after reading the discussion in here. I put it on about 70°C, placed the catechol and phenidone in while I was doing some other darkroom chores, and it easily went into suspension without overheating the mixture. I would encourage anyone who does much chemical mixing to purchase one (don't forget some teflon coated stir magnets!).

sanking said:

I know that there area a number of long-time Pyrocat-HD users on this forum. For those interested I would like to send you a 100ml bottle of the modified Stock A, which I will call for the moment Pyrocat2, for your evaluation. You can use your regular Stock B solution with this formula. I am primarily interested in personal feedback on results, but anyone who tests the variation should feel free to express their opinion here or elsewhere about it.

Sandy.

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BTW, I now have as many volunteers as are needed to test the new variation. Thanks to everyone who contacted me. The samples will be mailed in approximately 2-3 weeks.

Best,

Sandy

Sandy, just a general question on Pyrocat-HD. If there an emulsion (film) that Pyrocat-HD can't be used with or not recommended to be used with?

Curt

I can not give you a complete answer to the question because so much depends on format and personal likes. There are some combinations that I personally would not recommend for Pyrocat-HD because of grain size, such as TRI-X and HP5+ in 35mm size. However, there are some people who like a lot of grain in their prints, Rodianl devotees for example, and those persons might like the look. Also, certain films, BPF for example, tend to develop a lot of B+F with the very long development times we sometimes need for alterntive printing. However, so far as I know there is no film that is absolutely incompatible with Pyrocat.

Sandy

Curt said:

Sandy, just a general question on Pyrocat-HD. If there an emulsion (film) that Pyrocat-HD can't be used with or not recommended to be used with?

Curt

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sanking said:

BTW, I now have as many volunteers as are needed to test the new variation. Thanks to everyone who contacted me. The samples will be mailed in approximately 2-3 weeks.

Best,

Sandy

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Sandy
I had sent you a PM about getting a test quantity of this. Im not sure if Im one of the above "volunteers" but wanted to say that if I am there may be some better suited, experienced, and knowledgeable people to include than myself. Keep that in mind if so. Am looking forward to what people have to say about this new variation.

Thank you Sandy,

I currently use Rodinal, for about 30 years, and HC-110, off and on for about the same. I bought some Pyrocat-HD from formulary and if it is what I think it is, I might be using it exclusively. I am getting to the point that if I like it I will start making my own. I like to use a 25 ASA/ISO in 120 roll film and in 4x 5x 8x I have a lot of 400. I know it should be great with sheet film, it's the roll film that I wonder about. I may start using Rollei 25 for all of my 120 mf.

I have not mixed it up yet but four rolls from now I am going for it.


Thanks for the help,

Curt

Pyrocat+120 Film

Curt-I've used pyrocat-hd on lots of rollfilm with a mechanized rollerbase. It works great. If you do it this way reduce development time by about 20%
Best, Peter

I developed three rolls of film with Pyrocat-HD, from formulary, and WOW what nice looking negatives. I haven't run the numbers but making my own should be less expensive right? And of course I will have control in the mixing. Should I start with the Alcohol version right off the bat or make the original formula? Thank you Sandy for the great developer.

Curt

Hi Curt,

Pleased to hear of your good results.

The alcohol version is simply a method for getting phenidone into solution faster than if mixing with water. This method was included in the original instructions for mixing Pyrocat-HD so it should be considered part and parcel to the original formula.

And allow me to clarify. There will be no major changes to the Pyrocat-HD formula. The new version that I mentioned at the start of this thread will have a new name, since it involves a major variation in terms of reducer . Not sure yet what I will call it, but it will not be Pyrocat-HD.

Best,

Sandy

Curt said:

I developed three rolls of film with Pyrocat-HD, from formulary, and WOW what nice looking negatives. I haven't run the numbers but making my own should be less expensive right? And of course I will have control in the mixing. Should I start with the Alcohol version right off the bat or make the original formula? Thank you Sandy for the great developer.

Curt

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Super concentrated Pyrocat HD

Has anyone tried making up a more concentrated solution of Part A.

The reason for asking is I make up Pyrocat in the UkK on each trip home & fly back with it. In the past I've flown with both parts made up, then more recently just Part A and the Carbonate for Part B, 2 litres of Pyrocat (both parts) is just over 10% of my luggage allowance when flying, so quite significant.

I can buy Potassium Carbonate in Turkey so that cuts the weight, but I want to cut the weight further.

In the past I've not used Glycol but found my Pyrocat lasts up to 18months anyway stored properly.

This time I've used Digol (Diethylene Glycol) and could probably have dissolve the chemicals for 1 litre of stock solution in 250ml, but in the end used 300ml Digol & 200ml water to make up 500ml of double strength as I had an old Rodinal bottle handy. I don't intend to use it at this strength rather make it up the normal concentration when I need it.

This cuts the weight I fly with to around 25%, assuming I buy the Potassium Carbonate later.

Ian

I once mixed it 2X or 4X strength in water and all of the chemicals went into solution easily. Probably would in diethylene glycol as well but can not state that for sure.

BTW, if you plan to mix in diethylene glycol I advise substituting 4.0 g of ascorbic acid for the metabisulfite, and just leave out the bromide.

Sandy

Ian Grant said:

Has anyone tried making up a more concentrated solution of Part A.

Ian

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sanking said:

BTW, if you plan to mix in diethylene glycol I advise substituting 4.0 g of ascorbic acid for the metabisulfite, and just leave out the bromide.

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All but the Metabisulphite dissolved easily in the Diethylene Glycol, next time I'm back in the UK I'll try using Ascorbic Acid instead. Thanks Sandy.

Ian