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 email@example.com. 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
Last edited by sanking; 02-19-2006 at 12:29 PM. Click to view previous post history.
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
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.
Originally Posted by noseoil
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.
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.)
Originally Posted by sanking
Let me know if you are interested.
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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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.
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.
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.
Originally Posted by Kirk Keyes
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.
Originally Posted by Daniel Lawton
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.
Originally Posted by colrehogan
Originally Posted by sanking
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.