From: wcharmon (wcharmon@wt.net)
Date: 04/23/02-11:12:33 AM Z
Yet another thought. You ARE mixing 100g into 100ml of water
aren't you, and NOT adding water to 100g of solid to make
100ml total solution? The formula is not truly a 100%
solution, since the total volume increases when you add the
carbonate to the water. It is more in the 80% range, if
you're into hair-splitting. I have never had a problem
getting it to dissolve, and it is kinda interesting that it
is definitely an exothermic reaction. I leave the solution
in a mixing beaker for a while to cool before I put it in a
bottle for long term storage.
BTW, I have begun using the pyrocat HD at 1.5:3:100 for some
of the weakish Bergger and Forte films. It really adds some
pop for films that have naturally higher contrast. I have
all this data assembled in spreadsheet form for Tri-X,
Tmax400, FP4, HP5 and Fortepan400 for this dilution. Send me
an offlist request, and I'll forward the data to you.
Clay
Clay
> >Joe,
> >
> >Potassium carbonate is soluble in water up to about
> 125-135%, which
> >means that you should be able to dissolve at least as
> much as 125g
> >in 100ml of water. I have been working with this formula
> for about
> >three years and have never had any problem in mixing the
> 100%
> >solution. I add the potassium carbonate slowly to the
> water because
> >there is quite a lot of heat produced from the mixture.
> It should
> >dissolve completely in 30 minutes or less.
> >
> >Sandy
> >
> >
> >
> >
> >
> >
> >>Okay folks, I give, how do you keep 100 grams of the
> carbonate dissolved in
> >>100 mls of water? It has been three days and the best
> that can be said is
> >>the "B" is a slurry. For the record, the chemicals are
> analytical grade and
> >>the water is distilled. I have been using the 10%
> solution B and watching
> >>the threads on this subject decided to try the 100%
> solution.
> >>
> >>How about this as an alternative, since the formula is
> calling for 1:1:100
> >>(or 2:2:100 depending what one is doing), and the 100%
> shows B actually
> >>being 1 gram of pot carbonate per 100 mls of water, why
> not add the
> >>appropriate amount of dry carbonate to the working
> solution. If my logic
> >>works out right, that would be 10 grams per 1000 mls of
> working solution.
> >>Just mix the appropriate amount of carbonate to the
> water then add the A.
> >>OTOH, why not mix up a big batch of 1% carbonate and add
> the part A as
> >>needed? Does the carbonate keep? in solution? Does this
> sound feasible?
> >
> >
> >--
>
>
> --
>
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