Å®ÉúСÊÓƵ

A company that recycles fixing solution, used in the development of
photographs, has rebuffed suggestions by Kodak, the world’s biggest photographic
supplier, that its process does not work. The British arm of Continufix,
based in Slough, insists that it can recycle a batch of the chemical repeatedly
without loss of quality. The company takes in fixing solution laden with
silver from photographic laboratories, and uses a patented technique to
cleanse it before returning the fixer for reuse.

However, Peter Sutherst, manager of Kodak’s professional technical support
group in Britain, says, ‘We do not believe that the recycling of solutions,
except in rare cases, is the way forward. This uses old technology.’

Professional photographers report that Kodak technical staff have said
they ‘would not recommend the use’ of Continufix’s process with its advanced
products, claiming it does not regenerate the fixer to Kodak’s original
specification due to the build-up of halides such as iodides, bromides and
chlorides as by-products from the developing process.

Using fixing solution is one of the last stages in photographic development
and processing. It ensures that the silver (in black-and-white photographs)
or dyes (in colour photographs) do not shift once they have been developed.

Continufix’s director Chris Malcolm says: ‘We have customers in the
US and Canada that have been with us for years, through hundreds of regenerations.
Why don’t Kodak give it a fair trial at a place of their choosing, using
all their own products?’

A Kodak report in August on tests of the process at its facilities in
Rochester, New York, concluded that ‘We did not encounter problems in the
limited amount of reuse we conducted’ but adds that ‘a general statement
cannot be made about how long such solutions can be reused’ without extensive
further tests. It also concludes, ‘The recycling process will not go on
´Ú´Ç°ù±ð±¹±ð°ù.’

Continufix has signed up 180 customers in Britain since opening in June,
says Malcolm, and it is recycling 1500 to 2000 litres of fixer a week –
still a small part of the British consumption of nearly 200 million litres
a year. Most of this ends up in the sewers, though Kodak does operate a
‘haul away’ scheme: used fixer is biodigested prior to discharge in the
River Mersey.

The main active ingredient in photographic fixer is sodium or ammonium
thiosulphate. It dissolves unexposed silver halide on film or paper to form
soluble silver thiosulphate complexes, so a tray of fixer gradually becomes
less effective as silver builds up in it. Any large-scale processor will
remove the silver by electrolysis before getting rid of the fixer, as the
recovered metal is worth about $5 per ounce. The spent fixer – containing
silver residues and traces of heavy metals such as cadmium and mercury –
is then disposed of.

Continufix, by contrast, uses a method originally developed by the University
of Alberta’s department of mining and licensed in 1990. It adds sodium
hydrosulphide (NaHS) to the spent fixer to precipitate insoluble metal sulphides,
which are disposed of separately after the silver has been removed. In the
process the thiosulphate is reconstituted, says the company’s chemist, Darren
Budd. The only difference, he says, is the creation of a small amount of
salt or other sodium halide. He claims that hundreds of regenerations can
be performed with no deterioration in the activity of the fixer.

One processor which enjoys ‘Kodak Q-Lab’ quality control certification
says there were no problems after three regenerations despite using several
hundred litres of fixer a week. ‘My checks show no change in the chemicals,’
said the laboratory’s manager, who did not wish to be identified. ‘Had there
been any problems we would have gone straight back to virgin Kodak fixer.’

He has adopted the process, he says, for three reasons: ‘First comes
the environment: we’re not tipping the stuff down the drain anymore. Second
is the time we save not mixing up new chemicals, since the fixer comes back
ready to go straight into the tank. Last, there is a slight cost saving.’

Malcolm Green, professor of inorganic chemistry at the University of
Oxford, says the dispute could easily be resolved by reference to a competent
independent laboratory. ‘If Kodak are correct in their misgivings, they
will be able to provide chapter and verse,’ he added. ‘They should publish
a scientific paper detailing their objections.’