Re: [Leica] HP5+ 4"x"5 sheet in D76 using Jobo tank

["Dan Post" <dpost@triad.rr.com>]

Bee Lian-
Hello! My experience with D-76, replenished, is that they recommend a rep
rate of one ounce or 30ml per 80 square inches of film- this translates into
one 8x10 sheet or four 4x5 sheets, or one 36 exposure roll of 35mm. Even
adding the full one once when I ran several 24 exposure rolls didn't seem to
adversely affect the mix.
Doing it in stock solution replenished is no problem, though there are those
who swear that you have to use it 1:1 or 1:3. I found that the accumulated
bromide in the replenished stock gave a better tone (less 'harsh') and
slightly finer grain after several rolls. Sort of a chemical 'bokeh'! I did,
however, shoot some "Dustoff" (R) into the top of the stock and replensisher
jugs to exclude air- though any oif the dusters will work- all have gasses
that are heavier than air and settle on the top of the solutions.
I would say that the minimum solution would be, as in a small tank, at least
8 ounces or 250ml per 80 square inches- I think that Jobo is possibly
concerned with overfilling the tank and it sloshing out?
When I did film in a tube, I filled the tank nearly full- full enough to
cover the film when rolling, but with enough head space to assure that there
was some agitation, and the solution didn't just roll around and not move
because of its own inertia.
D-76 is an older formula, and they used to warn about 'aerial' or dichroic
fog- now, this may be a characteristic of older films, or the developer, it
never was made clear to me, but lifting the film out of the solution- as in
the old days when you dipped and dunked in a tray, counting butterflies in
the dark, the tendency was for some silver to oxidise in the air, and form a
'fog' that did not fix out, and cut contrast. It was called 'dichroic' fog
because the silver layer was very thin, and when the negative was viewed
obliquely, you could see a yellow/blue haze on the film.... that's as well
as I can describe it! I do know that if you get it- you will recognize it
immediately.
Now- to HP5. I do it in a small tank, and only did Tri-x 4x5 sheets. I
imagine they are somewhat the same. I do know that the Tri-X sheet film had
a substantially more robust emulsion than the 35mm film of the same name. It
was also toothed or textured for retouching as I recall, and required a
slightly longer development time.
All things considered- I'd run a couple of tests, especially since you do
your rolling by hand. get the time and temperature adjusted so that with
your style of agitation you get negatives with the proper range of tones.
I think in your case that this will be very important- most of my friends
and I have different agitation styles! I am laid back- make two inversions
in five seconds, every 30 seconds, whereas I think my friend Bob shakes his
like a cocktail shaker! We have to use different times, just from the
differences in agitation.
I hope this helps, and best of light to you!
Dan (Doin' it in the dark) Post