Three Pyrocat HD/PMK Questions

[Tom Kershaw]

Does anyone know what the capacity of PC-HD is? i.e. square-inches of film per litre of working solution.

Thanks,

Tom

 

[sanking]

Does anyone know what the capacity of PC-HD is? i.e. square-inches of film per litre of working solution.

Thanks,

Tom

All of my testing (which is in BTZS type tubes with constant agitation) is based on the use of 75 ml of the 1:1:100 working solution per twenty square inches of film, or a sheet of 4X5" film. This amounts to a minimum of 250 ml of developer per sheet of 8X10" film.

One might be able to get away with slightly less solution, but at the risk of longer development times and perhaps slightly increased B+F from general stain.

Sandy

 

[DeanC]

Just eyeballing the two negatives (4x5 step wedges contact printed onto 4x5 FP4+) they both look identical and appropriately developed (2:2:100, 70F, 11min rotary.) I'll throw them in the densitometer when I get home from work tomorrow night to be sure, but I think I've got 2 good liters of Stock A. That should be enough to last me while, eh?

Looks like the first batch (the one where it looked like the metabisulfite hadn't dissolved all the way at first) developed my test sheet out to an avg. gradient of 0.77 and the second batch (the one that looked a little cloudy) developed an identically exposed sheet out to an avg. gradient of 0.71. Both measured on the blue channel of my densitometer.

Seems like they both work with the first solution being slight more active.

Dean

 

[sanking]

Looks like the first batch (the one where it looked like the metabisulfite hadn't dissolved all the way at first) developed my test sheet out to an avg. gradient of 0.77 and the second batch (the one that looked a little cloudy) developed an identically exposed sheet out to an avg. gradient of 0.71. Both measured on the blue channel of my densitometer.

Seems like they both work with the first solution being slight more active.

Dean

The slightly greater activity could also be due to the fact that some of the potassium bromide did not get completely dissolved in the solution. I find that the bromide is even harder to dissolve than the metabisulfite. Slightly greater activity would be expected if that were the case.
Sandy

 

[DeanC]

The slightly greater activity could also be due to the fact that some of the potassium bromide did not get completely dissolved in the solution. I find that the bromide is even harder to dissolve than the metabisulfite. Slightly greater activity would be expected if that were the case.
Sandy

Interesting. So the bromide restrains the activity somewhat? I guess I'll hang onto both batches and just make a note somewhere that when I switch to the second I should bump up development time by about 10%...

Dean

 

[sanking]

Interesting. So the bromide restrains the activity somewhat? I guess I'll hang onto both batches and just make a note somewhere that when I switch to the second I should bump up development time by about 10%...

Dean

Yes, the bromide serves as a restrainer in the formula to prevent the development of unexposed halides which would result in chemical fog. If the amount of restrainer in the formula is perfectly balanced the film will develop to a very low B+F. Too little restrainer will result in increased activity, and slightly elevated EFS values, but higher B+F values. Too much restrainer and the film will develop with no fog but with reduced EFS values.


Sandy

 

[gainer]

Sandy,
I don't remember if you reported the effects of using benzotriazole in place of bromide. If it works, is it more easily soluble in glycol?

 

[sanking]

Sandy,
I don't remember if you reported the effects of using benzotriazole in place of bromide. If it works, is it more easily soluble in glycol?

I actually never tried using benzotriazole in place of bromide in the pyrocat formula. I tried both bromide and benzotriazole as a restrainer in the PC-TEA formula, and think I sent you some data on both. As I recall (this testing was done in the spring), both bromide and benzotriazole went into solution equally well in TEA, and both worked equally well, though the latter is more efficient when measured by mg. I have assumed that benzotriazole would dissolve in glycol as well as in TEA but if I were to substitute it at this point in the Pyrocat-HD formula I would lose a degree of precision in the data from my film tests, especially in terms of EFS.

Sandy

 

[gainer]

What about iodine? Tincture of iodine should dissolve readily in glycol. Maybe its too effective. I guess I should try it. I think I will. Don't hold your breath waiting for the results. I'm unusually lazy in the winter.

 

[Kirk Keyes]

If you want to use iodine, just try potassium iodide, as it is a lot less messy than the tincture and will be easier to measure accurately.

Kirk - www.keyesphoto.com

 

[gainer]

I've read that the reaction products of potassium iodode in some developers, are very difficult to wash out of film. Any truth to that?

I don't know, but I believe that one of the differences between traditional and T-grain films is the silver iodide content, and they are certainly more difficult to fix.

With regard to potassium iodide, is it any more soluble in glycol than potassium bromide? The tincture, IIRC, is an alcohol solution, which usually means it can be dissolved in glycols. It would have the advantage that much less is usually required to get a given restraining action, so solubility may be less an issue.

 

[Ole]

Hang on there - there's a BIG difference between iodine and iodide! Do not confuse the two!

Silver and iodine will combine to form silver iodide, yes. Silver iodide is 10 times (roughly) more insoluble than silver bromide, which is what makes it difficult to remove in the fix.

The solubility is proportionally the same in any polar solvent, including water, alcohol, and TEA.

"Tincture" is a solution of iodine in alcohol. Forget about it, it's not photographically relevant (in the post-Daguerre era).

Iodide is a very strong "restrainer" in developers. In most cases it's far too strong in anything but homeopathic (sp?) amounts. If bromide and Benzotriazole is not enough, try Pinacryptol. Iodine is just too sensitive in measurable quantities.

 

[Kirk Keyes]

With regard to potassium iodide, is it any more soluble in glycol than potassium bromide? The tincture, IIRC, is an alcohol solution, which usually means it can be dissolved in glycols. It would have the advantage that much less is usually required to get a given restraining action, so solubility may be less an issue.

I would suspect that potassium iodide is going to be similar in solubility to the bromide in glycol or TEA - I'll leave that up to you glycol/TEA guys to determine as I have not been bitten by that bug yet...

But like Ole says, there is a big difference between iodine and iodide. And he is correct in all he says in his post about the differences. I suspect that iodine may be a little more reactive than you want, and not in a good way! I suspect it would fog the film. Iodine, chlorine, peroxide, I believe they all fag film. (I don't have my references with me as I am 2000 miles away from them.)

 

[gainer]

Well, the iodine will come in contact with an alkaline solution before it meets any silver, and I suspect it would form the iodide at that time. After development begins, how much ionic silver will we have in solution to react with the iodide? I won't be embarrassed if I try it and it doesn't work. Will the theoretical nay sayers be embarrassed if it does?

If you ever do get over your prejudices and try the glycol idea, you might like it. We mustn't have that. You would be able to try sulfite free developers and find that what everyone knows about sulfite is not universally true. Oh well. Merry Christmas.

 

[Kirk Keyes]

Well, the iodine will come in contact with an alkaline solution before it meets any silver, and I suspect it would form the iodide at that time. After development begins, how much ionic silver will we have in solution to react with the iodide? I won't be embarrassed if I try it and it doesn't work. Will the theoretical nay sayers be embarrassed if it does?

If you ever do get over your prejudices and try the glycol idea, you might like it. We mustn't have that. You would be able to try sulfite free developers and find that what everyone knows about sulfite is not universally true. Oh well. Merry Christmas.

I'm interested to see the results from your tincture of iodine test. It will be interesting, no doubt.

It's not that I'm prejudiced - no need to make that assertion! It's just that for the developers I use (PMK and XTOL), and the amounts I use, I find I do fine with the classical methods.

Kirk - www.keyesphoto.com

 

[gainer]

I know from experience that PMK lives forever, along with Rodinal and HC110. Pyrocat in the original formula is no slouch either. Xtol does not, so it depends on how fast you can use it. I tried it when it first came out, before all the hubbub about it's failing without warning. Now the package is too big. I can make a stock that is as concentrated as HC110 or Rodinal, that has fine grain and high sharpness, and that will be ready to go when I want it. It can be a staining developer or not. I can even use hydroquinone as a staining developer.

The worst part of it is that I'm not making any coin of the realm by doing it. I'm surely having fun, though.

 

[sanking]

Sandy,
I don't remember if you reported the effects of using benzotriazole in place of bromide. If it works, is it more easily soluble in glycol?

OK, I finally got around to testing this. The anwer is yes, benzotriazole is much more soluble in glycol than potassium bromide. In percent solutions ranging from 1-5% benzotriazole goes into solution quite readily in glycol at a relatively low temperaature, i.e. 170º F or less.


This worked for me with both dipropylene glycol and propylene glycol in the percentages noted above.

At some point in the future I will do some tests to establish an equivalent substitution of benzotriazole for potassium bromide. Meanwhile, just mix in the potassium bromide with the glycol at about 250º F and stir until it goes into solution.

Sandy

 

[gainer]

I'm glad to hear about benzotriazole. I looked at my tincture of iodine, and it is 2% iodine and 2.4% sodium iodide in a 60% alcohol solution. Povidone is 1% available iodine and seems to dissolve easily in glycol or TEA. I did a R&D test with it (that means rough and dirty) but I can see it will take a lot of careful trials to find out if it is worth using and if so, how much. The references I found reported that iodide is much more active than bromide, that a very small concentration could shorten the induction period of hydroquinone, but no quantitative information.