Preparing Microphen stock solution...

[alexz]

I'm going to try my luck with Neopan 1600/1250 in Microphen, this is my first time I'll be trying other developer then NC110 to which I used to so far.
I have a pack of Microphen containing two parts A and B and there are instructions on th einner side of the box along with dev. times for different films and temp.derating chart.
Also, there is a table claiming 1 litre of stock solution is enough to develop 10 135-36 rolls which seems a bit confusing to me.
A single roll in a regular Jobo 1520 tank requires at least 240ml of the developer, twice as much is needed for 2 rolls developed in single session.
So, how it can be possible to develop 10 36-exp rolls in 1:0 (stock) solution which is 1 litre (as made from a single Microphen box) ? I tend to consider no more then 4 rolls can be made of it...

What do I miss ?

Additional quiz: the recommended dev. time for Neopan 1600 is 3.5 minutes in 20 deg. (by both Microphen box and Massive Dev. Chart). Soundsa leerily to me (I used to considerably longer times with HC110 sol. H for Tri-X). So I'll be trying to derate according to temp. derating charts on the box.
According to that chart, in order to reach 5 minutes of development I need to decrease the temp. to approx. 16 deg. C. This is my first time I'm trying to step off the standard 20 deg. approach, so would appreciate if you can check my calc.out...
Thanks

 

[peterc]

if you use the developer as a one-shot solution, you'll only get 4 rolls out of it. However, you can pour the developer back into the stock bottle after use and reuse. But, for microphen, you have to add 10% to the developing time for each reuse. So, roll 1 is developed for the recommended time, roll 2 for that time +10% and so on.
Yes, according to Ilford's specs, 5 min would be correct for Neopan 1600 at 16C.
Microphen is a very active developer, usually used for pushing, which is why the times are so short at rated speed.

 

[drewbarb]

Peter is right- Microphen is very active. It works very well with multiple uses at full strength. I interpret the 10 rolls to mean it can be re-used that many times- so long as you increase your time by 10% with each use. I've used (and re-used) Microphen this way successfully for years. I mix up two liters at a time, and store it in two two-liter bottles- one for unused solution, marked "Fresh"; the other for used, marked "One Run". Obviously this bottle will start out empty. After I process film with developer from the "Fresh" bottle, I pour it into the "One Run" bottle. When the "Fresh" bottle is empty, I re-label it "Two-Runs", and begin processing from the "One Run" bottle, increasing my times by 10%. The used dev then goes into the "Two Run" bottle, and so on. I continue in this way, going from one bottle to the next and increasing my times by 10% after each use until I have used all the solution 10 times, or until it's two months old, which ever comes first, at which point I dump it and start fresh.

I only use it for push processing, so my times are generally long enough that I don't run into un-even develpment. Neopan 1600 shot at EI 1600 is a push (this film is really about an 800 speed, I think). In any case, I find the Massive Dev chart times to be a bit too short. At EI 1600, I actually get 5.5 minutes at 68F/20C; for your EI of 1250, I would just try it at 5 minutes- though, as always with a new developer or EI, I would run a test clip first. Comparing times against HC110 at dilution H isn't useful, since these are different developers- not to mention the fact that you are comparing one at full strength to another at fairly high dilution- either way, comparison of times is moot.

Anyway, do some testing, have fun. Microphen is an excellent developer, especially with fast and/or pushed films. Once you dial in your time, I bet you'll like the results.

 

[alexz]

Thanks guys, sounds pretty encouraging...
Drew, you apparently anticipated my next question which would be about re-use: whether to separate re-used slution frmo the stock one or pour the re-used into the stock, but your "two bottles trick" clarified the issue. Thanks.
I think I'll give a shot to 5 min at 16 deg. C for both 1600 and 1250 as my starting points and will get further from there,,,,

 

[drewbarb]

You don't really have to separate the used from the unused. For a few years, I used to just dump it back into one bottle- it works fine as self-replenishing. I started doing the separate bottles trick to more easily track when to increase the times. It's a bit compulsive and not strictly necessary, but it works well.

 

[alexz]

But if you just dump it back mixing with a fresh stock solution, how to keep track of 10% raising step in dev. times ?

 

[MartinP]

You just stick a label on the bottle and mark a cross everytime you use it, whether for 1 or 2 rolls of 135, or a roll of 120.

There is a little chart in the pdf of instructions for the developers on the Ilford site. That will explain exactly what you need to do.

Basically for the first batch standard time (obviously), the second batch give an extra 10% per film, the second batch 20% per film etc. So that if you are doing two 135s at a time then the dev times are N, Nx120%, Nx140% etc etc. The last batch would be 190% of the standard time, but remember that it is based on the actual number of rolls and not the number of processing runs.

There is plenty of information on the Ilford site. Have fun.

 

[alexz]

Oh Martin, just after reading your post I realized Microphen if Ilford product...
Didn't realize it until that...

Will certainly visit their site checking for the info, if will find it still unclear - will get back to this thread asking to elaborate for slow catching brains...