Pyro in Unicolor

[bruce_schultz]

Just got a Unicolor machine and I like the results I get with Rodinal 1:50 for developing 8x10 Tri-x. But when I tried my preferred developer, Pyro PMK, the negative was terribly thin, even though I increased development time by about a third. What to do?

[ted_kaufman]

Basically, pyro oxidizes too rapidly with constant agitation, and

therefore, it doesn't matter if you increase the development because

the developer is shot. How much solution are you using? If 250ml or

less, then try 500ml and see if that corrects it. If not, you'll

have to try one of the other popular solutions: 1)Add EDTA (Calgon);

2)Double the "A" portion of your developer; 3)Double A & B ; 4)Dump

the developer midway though the cycle and add fresh solution. You'll

have to experiment to find what works for you. If I recall,

from "The Book of PYRO," Hutchings advises doubling A as a first step.

 

<p>

 

If all else fails, you can try Rollo Pyro (a formula somewhat like

PMK that uses considerably more pyro). Also, you might want to

consider a catechol based developer like Pyrocat-HD. See Ed

Buffalo's site, unblinkingeye.com, for the formula.

[pete_caluori]

Greetings,

 

<p>

 

I use a JOBO rotary processor with Pyro and get very good results.

If you use Hutchings PMK it will oxidize too fast. You need to

modify the formulation as was previously suggested, or use Rollo Pyro

or ABC+ Pyro, which use EDTA as a preservative.

 

<p>

 

Regards,

[linas_kudzma]

Bruce,

 

<p>

 

I use Unicolor 8x10 and 16x20 print drums and a Unicolor reversing

roller base to develop 8x10 and 8x20 sheet film. Rollo Pyro works

fine, but I like Pyrocat-HD even better. Pyrocat has never given me

streaks or any problems sometimes associated with staining developers

and film in print drums.