View Full Version : I think I learned a Pryocat lesson

27-Mar-2009, 22:13
Perhaps, I just found out that 500ml of Pyrocat HD.....is good for 6 sheets and no more.

After I developed the 6 sheets of 4x5, I reused the Developer for 4 more sheets.

they came out totally clear and void. :eek: :mad:

I read that when developer is "done" and does not develop the film, that the fixer will clear the film.

Is this, indeed the situation?

Jim Galli
27-Mar-2009, 22:20
Yep. Gives a whole new meaning for "1 shot developer" doesn't it. Ouch.

27-Mar-2009, 22:24
makes me glad I read a little blurb about "min of 75ml per 4x5 sheet"... guess I should have read a little further into that statement.

The good thing is, there is always a chance I can redo the images, they were portrait type shots.

Jim Galli
27-Mar-2009, 22:30
75ml per sheet is probably conservative. I routinely do 5 8X10's with 800ml of PyroCat. I used to change solution in the middle with 800 fresh but somewhere along the way I quit doing that. So that's 400 Sq. In. of film with 800 ml. You're only taxing your 500 ml with 120 In Sq, a much better ratio. It simply doesn't want to get used 2 times.

Jan Becket
27-Mar-2009, 23:37
Thanks for the reminder / warning, even if inadvertent. I use Pyrocat in a JOBO 1500 ATL and split 600ml into two separate 300ml bottles (4 min each), just to avoid any oxidation issues with the continuous rotation. Maybe overkill, but it seems to do well at the 1:1:100 suggested ratio.

Andrew O'Neill
27-Mar-2009, 23:53
Yup. Pyrocat-HD starts to slowly oxidize as soon as A and B are mixed in with the water and speeds up considerably during the development process. You've probably noticed that it has turned red when you dump it out. The colour of oxidization. If you leave it out longer, it'll turn completely black.
I recently did a test with an Amidol developer. That is pretty powerful stuff. I developed one 4x5 sheet in a BTZS tube with 60ml of the developer. I then developed another sheet in the same solution. Plotted their curves and they were for the most part, identical. Pyrocat-HD is a one-shot developer.

Ross Chambers
28-Mar-2009, 00:03
There doesn't seem to be any information regarding whether the 6 sheets were processed together (in a tank perhaps?) or separately (in trays perhaps?)

I sought information about Pyrocat HD capacity per 5x7" sheet (one at a time, in trays) on various fora and didn't receive specific specs. but answers along the lines: "the chemistry is in such small quantities, why re-use"

Since then I may have erred on the side of caution, but I make up 500ml of working solution at 2:2:100 for each sheet, and this does work.

However I do have a daylight tank for 6 sheets of 4x5" and a litre of Pyrocat HD for works fine.

I imagine that if trays are used oxidation must be an important factor.

It's certainly a slow procedure tray processing single sheets, mixing developer for the next sheet then stopping, fixing and washing; I recommend a good radio programme to keep you company.

Regards - Ross

Ross Chambers
28-Mar-2009, 00:06
. You've probably noticed that it has turned red when you dump it out. The colour of oxidization.

I thought that was the anti halation layer soaking out--live and learn.

Regards - Ross

28-Mar-2009, 07:12
The first 6 were all together, in single reel Jobo tank. After developing, it was a nice dark brown color. Film was washed.

Also the used Developer sat out in a graduate for another 15-20 minutes exposed to fresh air, before doing the next 4 sheets.

Maybe I can ebay my clear film sheets... ;)

28-Mar-2009, 08:50
Usually developer becomes exhausted somewhat gradually. The reason that developer's capacity is often discussed is for consistency, not because it stops working.

If you've got clear film its usually an indication of another problem. You should get a faint image even with the most weak and used up developer. Could be the shutter didn't fire or the dark slides were not pulled during exposure. These or something similar are way more likely IMO.

Also, 500ml of pyrocat will easily do more than 6 sheets, but the reuse of working solutions is never a good idea. That's one of murphy's false economies :D


(20 yrs. of income producing darkroom work)

28-Mar-2009, 09:00
Pyrocat is definitely meant to be used as a one-shot and discard developer, and especially when using minimum amounts of solution as we do with Jobo processing.

That said, I am surprised that your second bath of film came out totally clear. I would have expected the negatives to be weak and quite highly stained from using the developer a second time, but the fact that they were clear could indicate some other issue.

Sandy King

28-Mar-2009, 11:42
I'm almost positive I took the dark slide out before pressing the cable release :)

the developing time for the 1st 6 sheets (hp5) was 13min, the 4 sheets of fp4 was 8 minutes.

28-Mar-2009, 12:22
Wow, different film for the 2nd run, too. That is tempting fate, I would say. If I had some shots that I cared about, and had never used a certain developer, I would start with just developing one sheet, at the very least, to see how it goes. (More likely, I would shoot a test target and check the dev. with a sensitometer, actually)

But this is how we learn. I'll never forget having to go back to a customer with blank film in about 1983. I remember that guy just about every time I pour in the fixer.