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View Full Version : Pyrocat MC: TMY + TMX + ISO + DBI



Ken Lee
1-Jun-2008, 07:00
In addition to shorter developing times, Pyrocat MC has higher recommended film speeds than those for Pyrocat HD.

With Pyrocat MC, the recommended speed for TMY is ISO 500. Given that the suggested film speeds and developing times are points of departure - not cast in stone - has anyone arrived at a different film speed ?

(With Pyrocat HD, TMY is best for me, at ISO 200. After so many years, it's hard for me to imagine TMY as anything other than 1/2 the official speed. The same is true for TMX, and every other black and white film I've ever shot).

With Pyrocat MC, What is the recommended film speed for TMX ? And while we're at it, are the recommended developing times for TMX posted anywhere on the web ?

The MC formula, which turns purple when mixed, is transparent under Infra Red illumination. This means that it's just as easy to use for DBI (development by inspection), as the HD formula.

Jan Pedersen
1-Jun-2008, 15:13
Ken, i have used the MC version for a couple of years now and i don't get more than 250 Iso out of the TMY. I develop in Jobo expert's now but prior to that used hand inversion for 4x5 and again 250 was my concluded film speed. I don't have any experience with TMX.

Ken Lee
2-Jun-2008, 07:49
Thanks Jan !

I'm interested in TMX mostly for my Roll-Film cameras. I like having 6x9 images with no grain.

Don Hutton
2-Jun-2008, 08:43
In addition to shorter developing times, Pyrocat MC has higher recommended film speeds than those for Pyrocat HD.

With Pyrocat MC, the recommended speed for TMY is ISO 500. Given that the suggested film speeds and developing times are points of departure - not cast in stone - has anyone arrived at a different film speed ?

(With Pyrocat HD, TMY is best for me, at ISO 200. After so many years, it's hard for me to imagine TMY as anything other than 1/2 the official speed. The same is true for TMX, and every other black and white film I've ever shot).

With Pyrocat MC, What is the recommended film speed for TMX ? And while we're at it, are the recommended developing times for TMX posted anywhere on the web ?

The MC formula, which turns purple when mixed, is transparent under Infra Red illumination. This means that it's just as easy to use for DBI (development by inspection), as the HD formula.Ken

That EI of 500 you have seen may be for BTZS (i.e. for an incident shadow reading - you double the actual speed - eg from 250 to 500). So for conventional metering, it could be 250... As always, only your own testing can tell. I certainly don't get close to 500 with rotary processing. If you don't feel the need to "re-invent the wheel" and want to avoid a whole testing exercise, I'd use exactly the same EI and development as you use for HD and I bet you'll be very close.

Personally, I find MC and HD to give almost identical times with rotary processing - not by accident, I believe that the formulation of MC was fine tuned so that the developing times of HD and MC were almost the same.

As an aside, I personally get slightly higher B+F with MC than with HD - which is exactly the opposite of what's supposed to happen! However, I use generally use them interchangeably in the darkroom as I have about 1/2 gallon of each Part A solution mixed in Glycol - which should last a very long time!