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1. You guys - I have to laugh! Don't get me wrong, I've learned A LOT from this discussion. But you realize I just had a little bitty question about some TF-4 fixer...

Anyway, keep it up I'll just stand back here and observe!

2. We're good at that. No question is so "simple and innocuous" that we can't keep it running for at least three pages, developing new sidetracks on the way. It makes for interesting reading and hopeless achives...

3. Originally Posted by Ole
That's 20ml of 60% solution, or 12g per film.
Half a liter developer for a roll of film? It's in
the same range .... You end up at 24g per
Yes that's correct, 1/2 liter. One thing: The specific
gravity of that 60% is very nearly 1.3. The weight of
the A. Thio. only is more likely 20ml X 1.3 X 60%. That
be so I'm using 15 + grams. I'd have to think about it
some more to be sure.

Weights-Volumes, grams-milliliters; methods used in
photographic compounding can be confusing. Dan

4. Originally Posted by dancqu
Yes that's correct, 1/2 liter. One thing: The specific
gravity of that 60% is very nearly 1.3. The weight of
the A. Thio. only is more likely 20ml X 1.3 X 60%. That
be so I'm using 15 + grams. I'd have to think about it
some more to be sure.

Weights-Volumes, grams-milliliters; methods used in
photographic compounding can be confusing. Dan
Dan;

That 60% depends on whether it is wt/wt or wt/vol.

I have always taken it as wt/vol, which is what we used at EK, in which case 100 ml of 60% ammonium hypo contains 60 grams of ammonium hypo solid and the remainder (undetermined due to changes in volume of water due to hydrogen bonding and etc) is water to make up the 100 ml.

PE

5. Originally Posted by Photo Engineer
Dan; ... I have always taken it as wt/vol,
which is what we used at EK, in which case
100 ml of 60% ammonium hypo contains 60
grams of ammonium hypo solid and the
remainder ... is water to make
up the 100 ml. PE
Yes, that's correct. My mind must have jumped
track bringing specific gravity into the discussion.
So, Ole's and my amounts are the same; 12 grams
of the solid or 20ml of the 60% concentrate.

I've read of and measured the concentrate's
specific gravity. I needed information to establish
equivalencies twixt the S. and A. Thiosulfates. On
another occasion I used the Sp. G. to determine the
concentration of A. Thio. in some mixed up bottles
of diluted concentrate. Dan

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