Is it possible to mix one-shot PMK using TEA?

Loose Gravel · Apr 22, 2007

I'm not much of a chemist. I got to wondering about using TEA to mix part A of PMK and then not needing part B. Anybody tried this? Is the pH correct for everything to work?

Thanks for the comments. --LG--

gainer · Apr 22, 2007

It is possible, but you should substitute pyrogallol for catechol in Pyrocat MC because sulfite is not very soluble in TEA. I would rather use glycol as the solvent for an A solution and use TEA or Kodalk solution as B in order to retain the flexibility of a separate activator. My experiment with Hutchings' PMK A + TEA gave quite good results when I used the same amount of TEA that I would have used of the saturated Kodalk solution.

You might try Pyrocat MC if you have not already.

Tom Hoskinson · Apr 23, 2007

gainer said:
It is possible, but you should substitute pyrogallol for catechol in Pyrocat MC because sulfite is not very soluble in TEA. I would rather use glycol as the solvent for an A solution and use TEA or Kodalk solution as B in order to retain the flexibility of a separate activator. My experiment with Hutchings' PMK A + TEA gave quite good results when I used the same amount of TEA that I would have used of the saturated Kodalk solution.

You might try Pyrocat MC if you have not already.

Yes, I also recommend going to Pyrocat MC.

PhotoJim · Apr 23, 2007

PMK's stock solutions are among the most long-lived in photography (my stock solution is counting 7 years and still good). It would seem to me that having a single solution would defeat one of the largest advantages of PMK.

Mixing PMK at the time of development isn't too difficult.

Also, the oxidation that occurs when parts A and B of PMK are mixed is also what makes PMK a staining developer. If you could somehow mix up PMK so that it didn't oxidize, my instinct is that the staining effect would be a lot less.

Loose Gravel · Apr 23, 2007

Jim

I like PMK for its long life. I've been using it for a very long time and have never had it go flat on me. And it is convenient, but TEA is a pretty interesting chemical. I just thought maybe the two could come together somehow.

What are the advantages of pyrocat mc? over PMK. Keep it simple. 20 words or less.

gainer · Apr 23, 2007

Less overall stain, better sharpness, ask Sandy King.

Loose Gravel · Apr 23, 2007

And the disadvantages?

gainer · Apr 23, 2007

Anything I might say would be my opinion. I like both, but I do not use "alternate" printing methods that require UV light. Perhaps you could get more opinions if you opened another thread. I'm sure there are APUGers who have used both.

gainer · Apr 23, 2007

PhotoJim said:
PMK's stock solutions are among the most long-lived in photography (my stock solution is counting 7 years and still good). It would seem to me that having a single solution would defeat one of the largest advantages of PMK.

Mixing PMK at the time of development isn't too difficult.

Also, the oxidation that occurs when parts A and B of PMK are mixed is also what makes PMK a staining developer. If you could somehow mix up PMK so that it didn't oxidize, my instinct is that the staining effect would be a lot less.

The oxidation starts when you add water to the PMK-TEA mix. I agree that putting PMK up in TEA is like carrying coal to Newcastle, but if you have TEA and do not have Kodalk, TEA works.

Alan Johnson · Apr 23, 2007

I measured the approximate pH with pH paper of some working solutions:
TEA 1:50.....................................9.3
PMK-pyrogallol,metaborate..............9.7
Dixactol Ultra,pyrocatechol,carbonate,12
I believe the advantage of metaborate over carbonate is finer grain,also all the PMK times can be found at unblinkingeye.com

sanking · Apr 23, 2007

Alan Johnson said:
I measured the approximate pH with pH paper of some working solutions:
TEA 1:50.....................................9.3
PMK-pyrogallol,metaborate..............9.7
Dixactol Ultra,pyrocatechol,carbonate,12
I believe the advantage of metaborate over carbonate is finer grain,also all the PMK times can be found at unblinkingeye.com

Develoment theory suggests that when all things are equal developers of lower pH give finer grain. In practice, and as a general rule. this theory does not hold up well with developers that have a high percentage of proportional image stain. Grain is usually seen most prominently in the upper mid-tones and is caused by silver grain. In the high mid-tones a pyro stained negative has a high percentage of stain density, which is basically grainless.

In a very specific sense I don't see any difference in grain between developers like PMK and Rollo Pyro, which have working solutions of around pH 9.6, and and developers like Pyrocat-HD and -MC, or WD2D+, which have working solutions of around 10.9. All of these developers produce a lot of proportional stain.

ABC Pyro is a carbonate based developer that produces a lot of grain, but there are reasons for this other than the carbonate itself, primarily the fact that this developer has only one reducing agent, and because it does not produce nearly so much proportional stain as the developers mentioned above.

Sandy King

sanking · Apr 23, 2007

Loose Gravel said:
Jim

I like PMK for its long life. I've been using it for a very long time and have never had it go flat on me. And it is convenient, but TEA is a pretty interesting chemical. I just thought maybe the two could come together somehow.

What are the advantages of pyrocat mc? over PMK. Keep it simple. 20 words or less.

Since PMK has such long life when mixed in distilled water I just personally don't see any point in mixing it in TEA. The results will be similar, but mixing in TEA gives you less flexibility in mixing, and the high viscosity of solutions mixed in TEA is a decided disadvantage for me.

Sandy King

sanking · Apr 23, 2007

Loose Gravel said:
Jim

I like PMK for its long life. I've been using it for a very long time and have never had it go flat on me. And it is convenient, but TEA is a pretty interesting chemical. I just thought maybe the two could come together somehow.

What are the advantages of pyrocat mc? over PMK. Keep it simple. 20 words or less.

Lower B+F stain with long developing times. Greater effective stain with UV processes. Higher acutance due to intense tanning action.

That was 20 words!! And lots of MHO!

Sandy King

Loose Gravel · Apr 23, 2007

I want to thank you all for the explanations. I think I will try Pyro MC. Is the glycol just for shelf life? If I'm just going to give this a quick try, can I skip this chemical, as I don't have any?

(I should have mentioned at the beginning that I don't do UV processes and I print on VC papers.)

sanking · Apr 23, 2007

Loose Gravel said:
I want to thank you all for the explanations. I think I will try Pyro MC. Is the glycol just for shelf life? If I'm just going to give this a quick try, can I skip this chemical, as I don't have any?

(I should have mentioned at the beginning that I don't do UV processes and I print on VC papers.)

Yes, the glycol is there for shelf life. You can mix the stock solution in water, but I think it will go bad pretty fast without sulfite.

If you just want to test the working solution you can break down the amount of chemicals in a liter of stock according to the amount of solution you want. For example, if you want to make a liter of working solution equivalent to a 1:1:100 dilution just divide the amount of chemicals in a liter of stock by 100 and mix with water.

I hope I got that right!!

Sandy King

Loose Gravel · Apr 23, 2007

Sanking, thanks so much. I know what you mean. I'm un-employed for a few days, so I've got time to give it a go.

gainer · Apr 23, 2007

You can also use glycerine in place of glycol, though it is more viscous. You can get enough at the drugstore to give it a try.

Loose Gravel · Apr 24, 2007

Glycerine I happen to have. A friend of mine left it here. Looks like it has never been opened. Time to use it.

Is it possible to mix one-shot PMK using TEA?

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