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Hi Harlan!
Long time no see (the same Harlan at Photo Form,
correct??)!
This is really useful, this water solubility,
though in what I will be working on which is a 5% solution I probably won't come
up against it. But now I understand one usefulness of different forms
of the thio. The water solubility, for instance, would be understandable when
making bleach solutions, or sabattier developer, which both use potassium
bromide.
Thio is a fogger, so that is what I am working on.
I have both sodium and potassium thio, sodium and potassium hydroxide, and
sodium and potassium bromide in my cabinet. I use the sodium hydroxide in
thiourea toning, and was basically wondering if I could use up both forms in the
thiourea toning (and both forms of the thiocy in fogging) with the same
results. So I will proceed as if they are interchangeable except doing the
weight calculations as DJ said.
I had originally bought the potassium hydroxide for
mixing my own lith developer but no longer do that because I find the Fotospeed
Lith developer works great. Likewise, the others I don't use
anymore.
Chris
__________________
----- Original Message -----
Sent: Saturday, September 26, 2009 10:49
PM
Subject: Re: potassium and sodium
thiocyanate
Chris,
Often potassium salts tend to be significantly
more water soluble by weight than sodium salts. For example,
87g sodium
thiocyanate will dissolve in 100ml water while 217g potassium thiocyanate will
dissolve in 100ml water.
On the other hand, sodium and potassium hydroxide
have roughly equal solubility in water so it is not a universal
property.
The trend of often high potassium salt solubility can be
useful sometimes
though.
-Harlan
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