psvensson said:I make fractional batches that I use right after mixing. I have good consistency, but it's a bit of drag to weigh the ascorbic acid every time.
For 35 mm I use, in order of mixing:
1L water
50g sulfite (two tablespoons)
2 g ascorbic acid
5 ml phenidone 1% in 91% rubbing alcohol
Canuck said:I use some generic vitamin-c tablets from Costco. At 500 mg, I would just pop 4 into solution. No weighing. It includes some inert material but hasn't affected anything yet.
psvensson said:"Somebody is bound to come by and say the sulfite is not
necessary, and that there are better accelerators. Let me
reply in advance: I get finer grain with sulfite than with any
other method I've tried."
I keep a least chemistry approach in mind. Remember, I'm the
fellow that processes one-shot with one tray. The less chemistry
needed to compound the better. D-76 is loaded with sulfite
while types like FX-1, Beutlers, Rodinal, etc, have very
little but are best for slower already fine grain films.
Lowering the ph leads to finer grain but slower emulsion speeds.
I was using D23, my 8 and 80 gram version, for a while but thought
perhaps I was losing film speed due to low ph. On the assumption
that metol has a not so low turn on ph range I switched to
carbonate. I think my film speed is up some but can't
quantify. I've a fine densitometer but short on time.
I recall having read that there is an optimal sulfite level per unit
volume. I remember, an article by R. Suzuki. Dan
"There are good sulfite-free developers too, and they may
meet your needs. But if you like the look of D-76, I think you
will more likelyprefer a sulfite-based developer. For low-speed
films, this would be less of a consideration."
Ronald Moravec said:I have tried all sorts of thing over the years and recently
tried undiluted D76, your formula, and find it the best. Just
put it in small one time use bottles just after mixing so air can`t
get to it. You get unpredictable activity level changes if it
does. NO HALF FULL BOTTLES even for a week.
Fractional batches are a waste as it will last 6 months in the
dark with no air and you start getting into measurement
problenms. And D76 should sit 24 hr before use.
Tri x is five minutes at 68 with agitation 5/30.
Gerald Koch said:The problem with the activity of D-76 changing upon storage
and becoming more active is caused by a complex reaction of
the hydroquinone.
Grant Haist suggested a viariant of D-76 which eliminated the
problem by eliminating the hydroquinone from D-76. The
modified formula is called D-76H and it works very well
and keeps in partially filled containers.
Metol ......................... 2.5 g
Sodium sulfite (anhy)..... 100 g
Borax ......................... 2.0 g
Water to make ............. 1.0 l
Gerald Koch said:"Borax is a stable chemical and does not hydrolyse in water.
In fact, it is used as a reference to calibrate pH meters;
a 0.01M solution (3.814 g/l) has a pH of 9.22 at 20C."
Borax; ph 9.22 at 0.01M. I hope some others see that.
I've always maintained that sodium sulfite is more
alkaline than borax.
"When hydroquinone oxidizes in sulfite solution hydroxide ions
are produced which raise the pH of the solution."
That is only meaningful in the context of when D76 is coming
from; 1927. D76 78 years ago was, I believe, compounded
for large tank and tray processing and intended to be
replenished. For myself, small bottle storage and one
shot use obviate any need for borax. Dan
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