Pyro developer need help

[ferod]

Somebody can give me some info (dev. time, how much film i can make, if is one shot, and inversion method) for this formula:

Pextral 2 bath
TD-3

Thank you

 

[rwboyer]

I have not used this formula but I have just read it and here are a couple of thoughts:

This does not sound like a fantastic formula compared to many other more popular formulas for a couple of reasons - it is pyro only so it will probably not give you the best film speed, the alkali is a bit much compared to other formulas. I say this not to discourage you from experimentation but maybe to save that for a time when you are more comfortable with what results to expect and have something a little more mainstream to compare it with.

If you have a bunch of reasons you would like to go with that formula those reasons would most likely be satisfied with other Pyrocatechol formulas out there like Pyrocat HD. Pyrocat HD is readily available premixed and can also be mixed from scratch as the formula is available freely. Pyrocat HD (and other similar formulations) can be used one shot and also be used as a two bath. You will find many many many more people have experience with a wide range of films and development conditions with this formula (as well as ABC, PMK, etc, etc) and can probably give you some guidance to get the results you are looking for. With the formula mentioned above you maybe about the only one or two people using it.

There is a really good reason most Pyro formulas in common use have another developer and do not use such a strong accelerator.

RB

 

[ferod]

Hi rwboyer, i like work with catechol developer, my favourite are Moersch Finol and Ornano Nucleol BF200, this "Nucleol" is not a very stain dev, have only a little part of catechol.
So now i have this raw chemichal (catechin, sodium sluphite anhydrous, sodium hydroxide and sodium carbonate) so i find the formulas that having this chemic and are (TD-3, Windisch, Windisch modified, Pextral 2 bath, Byrd's pyro-cat, A.Adams compensating formula).
So i havent experience with this formulas, but i want try and understand what will be good for my work.
Thanks for you help.

 

[rwboyer]

Hi rwboyer, i like work with catechol developer, my favourite are Moersch Finol and Ornano Nucleol BF200, this "Nucleol" is not a very stain dev, have only a little part of catechol.
So now i have this raw chemichal (catechin, sodium sluphite anhydrous, sodium hydroxide and sodium carbonate) so i find the formulas that having this chemic and are (TD-3, Windisch, Windisch modified, Pextral 2 bath, Byrd's pyro-cat, A.Adams compensating formula).
So i havent experience with this formulas, but i want try and understand what will be good for my work.
Thanks for you help.

With one or two additional chemicals you could make just about any catechol formula including Pyrocat HD. I may be able to recommend some catechol formulas if you explained a little more about your typical work/style/materials and what you were looking for. Others that frequent this discussion could help out a little more as well if you shared some of those details.

RB

 

[kozesluk]

Pextral is a special two-bath developer&developing method invented by Ing. Koblic, not just only another_one_of_a_many_2_bath developers. Koblic himself wrote a comprehensive book about it. The developer needs to be agitated heavily and that's done by holding the both ends of film in hands (using a gloves of course) so the film is in "U" shaped "loop" and dragging the film through the developer in dish. This ensures proper air oxidation of film soaked with developer wich is important in the whole process.
I haven't tried it myself.
Unfortunately - almost everything you can find about Pextral developing method is in the book (written in Czech) and only some information is available on-line (also written in Czech).

 

[PhotoJim]

Just a word of caution: "pyro" usually refers to pyrogallol. Pyrocatechin is a different chemical and is often called catechol to avoid this ambiguity.

 

[Mahler_one]

Good advice Jim...I recall being confused about the names as well.

 

[largeformat pat]

I wonder how Pextral would work in a Jobo processor? This may help with the required agitation required.
Pat

 

[largeformat pat]

Dooh. too many requireds