I don't remember exactly what is in Permawash but its probably a
variation of Kodak Hypo Clearing Agent. KHCA consists of a mixture of
sodium sulfite and sodium metabisulfite adjusted to a pH of 7.0. It also
contains two sequestering agents, one of which is EDTA tetrasodium salt,
I have to look up the other. Both the sulfite and metabisulfite are
subject to oxidation over a long period just as in fixer and developer
but I don't think acetic acid is a resulting product although it might
be formed from the EDTA. OTOH, I am not a chemist. The main thing is
that any liquid concentrate has limited shelf life and working solutions
considerably less.
Mixing Kodak Rapid Selenium toner with KHCA was recommended for a
time when using high dilutions, about 1:20, for image protection. This
still works but IPI found it was not effective for microfilm. The
staining comes from a reaction of KRST to an acid condition of the
emulsion. Does not happen if the emulsion is neutral or slightly
alkaline. I have the patent formulas for KHCA somewhere. The most
important ingredients are the sulfite and metabisulfite. The
sequestering agents are to prevent deposition of aluminum salts from the
hardener in the fixer on the emulsion.
On 3/4/2017 1:04 PM, Tim Daneliuk wrote:
Today, I prepared to use some older (2011) PermaWash and it appears to have
turned into Acetic Acid.
At least that's what is smells like... intense vinegar.
I buy this stuff in gallons and normally pour it off into a quart container for
day to day use. Both
the quart and the gallon it came from exhibited this phenomenon.
I then opened a newer (2014) full gallon which smelled normal. To be on the
safe side, I filled a 3
quart brown glass bottles to minimize air exposure. The remainder went into my
"working" quart.
I've used the stuff for years and never seen this problem. It does make me
wonder if it was part/all
of the problem back when I was mixing toner and PermWash as a single step in
my workflow, and
experiencing edge staining on my prints.
Anyone have any theories about what is going on here?
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